Ballpoint pen refill and oil-based ballpoint pen

Abstract

To provide an oil-based ink composition for a ball-point pen capable of obtaining good handwriting with good writing feeling even in writing at a high speed or at a high writing pressure while effectively suppressing ink leakage, and hardly causing strike-through, and to provide a ball-point pen.SOLUTION: A ballpoint pen refill for an oil-based ballpoint pen includes an ink reservoir tube, an oil-based ink composition filled in the ink reservoir tube, and a ballpoint pen tip attached to a front end portion of the ink reservoir tube and configured to supply the oil-based ink composition, wherein the oil-based ink composition contains a first phosphoric acid ester which is a polyoxyethylene hydrocarbon phosphoric acid ester having a hydrocarbon group having 4 or more and 17 or less carbon atoms, a second phosphoric acid ester which is a polyoxyethylene hydrocarbon phosphoric acid ester having a hydrocarbon group having 18 or more and 24 or less carbon atoms, water, and a nonionic surfactant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a ballpoint pen refill and an oil-based ballpoint pen. [Background technology]

[0002] Oil-based inks for ballpoint pens and oil-based ballpoint pens that have a good writing feel and good handwriting have been proposed.

[0003] Patent Document 1 discloses a ballpoint pen ink that is resistant to smearing even when left standing for a long period of time, and that contains a colorant, an organic solvent, a triester of oleyl alcohol and phosphoric acid, and water.

[0004] Patent Document 2 discloses an oil-based ballpoint pen that uses an ink composition containing a colorant, an amide solvent, and a polyacrylic acid resin, and that has an improved writing feel, is free of smearing or bleeding in handwriting, and has good writing properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-106187 [Patent Document 2] Japanese Patent Publication No. 2022-184953 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the oil-based inks for ballpoint pens in Patent Documents 1 and 2 sometimes produce poor handwriting, such as smearing or ink blobbing, when writing at high speed (speed writing) or with high writing pressure. It is also desirable to be able to suppress ink leakage while obtaining a good writing feel and handwriting when writing at high speed or with high writing pressure.

[0007] In addition, in order to obtain a good writing feel with an oil-based ballpoint pen, it is possible to increase the amount of ink ejected when writing, but in this case, with a typical oil-based ballpoint pen, bleed-through (a condition in which the ink penetrates to the back of the paper being written on, making the handwriting visible from the back) is likely to occur.

[0008] In view of the above circumstances, at least one embodiment of the present invention aims to provide an oil-based ink composition for a ballpoint pen, and a ballpoint pen that can effectively suppress ink leakage, while providing a good writing feel and good handwriting even when writing at high speed or with high writing pressure, and that is less likely to cause bleed-through. [Means for solving the problem]

[0009] A ballpoint pen refill for an oil-based ballpoint pen according to at least one embodiment of the present invention comprises: an ink reservoir; an oil-based ink composition filled in the ink reservoir; a ballpoint pen tip attached to the front end of the ink reservoir tube so as to supply the oil-based ink composition; Equipped with The oil-based ink composition comprises a first phosphate ester that is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group having 4 to 17 carbon atoms; a second phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group having 18 to 24 carbon atoms; Water and a nonionic surfactant; Contains When written on paper conforming to the specifications of test paper B defined in JIS S 6061:2020 under the writing conditions of a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec, the amount of the oil-based ink composition discharged per 100 m of writing distance is 0.04 g or more and 0.30 g or less.

[0010] In addition, the oil-based ballpoint pen according to at least one embodiment of the present invention comprises: The ballpoint pen refill described above; a barrel in which the ballpoint pen refill is housed; Equipped with. [Effects of the Invention]

[0011] According to at least one embodiment of the present invention, there are provided an oil-based ink composition for a ballpoint pen, and a ballpoint pen, which can effectively suppress ink leakage, while providing a good writing feel and producing good handwriting even when writing at high speed or with high writing pressure, and which is less likely to cause bleed-through. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a vertical cross-sectional view showing a ballpoint pen according to an embodiment. [Figure 2] 2 is a vertical cross-sectional view showing a ballpoint pen refill used in the ballpoint pen shown in FIG. 1. [Figure 3] FIG. 3 is an enlarged vertical cross-sectional view showing part I in FIG. 2. [Figure 4] FIG. 4 is an enlarged vertical cross-sectional view of a test ballpoint pen tip showing part II in FIG. 3. [Figure 5] FIG. 2 is a vertical cross-sectional view showing dimension measurement points. [Figure 6] 6 is a cross-sectional view taken along the line III-III' in FIG. 5. [Figure 7] FIG. 1 shows character strings written in pen tip ink leakage confirmation tests 1 to 3. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0014] (Configuration of ballpoint pen refill and ballpoint pen) First, an oil-based ballpoint pen to which a ballpoint pen refill according to some embodiments is applied will be described. The oil-based ballpoint pen according to some embodiments includes a ballpoint pen tip and a ballpoint pen refill including an ink reservoir tube that contains an oil-based ink composition, and is configured so that the oil-based ink composition is supplied from the ink reservoir tube to the ballpoint pen tip.

[0015] Fig. 1 is a longitudinal cross-sectional view showing an oil-based ballpoint pen according to one embodiment. Fig. 2 is a longitudinal cross-sectional view showing a refill portion of the oil-based ballpoint pen shown in Fig. 1. The ballpoint pen 100 (oil-based ballpoint pen) shown in Fig. 1 includes a ballpoint pen refill 200 and an exterior body 300.

[0016] In the embodiment shown in FIG. 1 , exterior body 300 includes barrel 1, to which front barrel 2 and rear barrel 3 are detachably fastened by screwing. The surface of front barrel 2, which is made of a relatively hard material (e.g., resin), is covered with a relatively soft material (a soft member such as a softer resin) to form grip portion 4. Examples of the relatively hard resin material that forms front barrel 2 and rear barrel 3 include polycarbonate, polyethylene terephthalate, acrylic, acrylonitrile butadiene styrene copolymer (ABS), acrylonitrile styrene copolymer (AS), and polypropylene. Either a transparent or opaque material may be used. Furthermore, examples of the relatively soft resin material (soft member) that forms grip portion 4 include thermoplastic elastomer and soft acrylic. Either a transparent or opaque material may be used. Grip portion 4 is preferably a grip that is non-slip when held, such as a grip with an uneven surface, a triangular grip, a grip with a polygonal outer surface, or a grip with a fingerprint-like shape. Crown 5 is inserted into the inner hole of rear barrel 3 and attached and fixed by a concave-convex screw engagement at the rear of rear barrel 3, and the portion exposed from the rear end of rear barrel 3 is disposed so as to cover the base surface of clip 6 attached to the outer surface of rear barrel 3. Crown 5 is also cylindrical, and a groove formed inside it serves as a cam groove for the debit cam mechanism, regulating the sliding position of rotor 7 housed therein, and determining the forward and backward movement position of ballpoint pen refill 200 connected thereto as rotor 7 rotates when knock 8 is pressed in. A ballpoint pen refill 200 is housed in the barrel 1 so as to be movable back and forth. A resilient member 9 made of a coil spring or the like is disposed in front of the ballpoint pen refill 200, and urges the ballpoint pen refill 200 rearward. The rear end of the ballpoint pen refill 200 abuts against the tip of the rotor 7. In other words, this is a retractable ballpoint pen in which the ballpoint pen refill 200 protrudes and retracts from the opening at the tip of the barrel 1 when the knock 8 is pressed.

[0017] As shown in FIG. 2, the ballpoint pen refill 200 includes a ballpoint pen tip 10 as a writing part and an ink reservoir 12 connected to the ballpoint pen tip 10 via a tip holder 11 having a through-hole. The ballpoint pen tip 10 is attached to the front end of the ink reservoir 12. The ballpoint pen tip 10 has a ball 13 as a writing member and a ball holder 14 that rotatably holds the ball 13. The ink reservoir 12 is filled with an ink composition 15 so that the ink composition 15 is supplied to the ballpoint pen tip 10 (writing part). An ink backflow preventer 16 that is incompatible with the ink composition 15 is disposed in contact with the rear end interface of the ink composition 15, and a float 17 is disposed in contact with the ink backflow preventer 16. Note that a tail plug or the like that prevents leakage of the ink composition 15 may be disposed at the rear end of the ink reservoir 12 of the ballpoint pen refill 200 to create a ballpoint pen body that does not use an outer case 300. The inner diameter of the ink reservoir 12 may be 1.00 mm or more and 5.00 mm or less. An inner diameter of 1.00 mm or more and 3.10 mm or less is particularly preferred, as it provides good shape retention for the ink backflow preventive body 16, preventing the ink backflow preventive body 16 from flowing out, and preventing the ink backflow preventive body 16 from flowing out even without the float 17 in contact with the ink backflow preventive body 16. The thickness of the ink reservoir 12 can be calculated by subtracting the outer diameter from the inner diameter, and may be 0.50 mm or more and 10.0 mm or less. A thickness of 1.00 mm or more and 10.0 mm or less provides high gas barrier properties and can prevent evaporation of the ink solvent, and a thickness of 2.80 mm or more and 10.0 mm or less is even more preferred, as it provides particularly high gas barrier properties.

[0018] FIG. 3 is a diagram showing the configuration of the ballpoint pen tip 10 of a ballpoint pen refill 200 according to one embodiment, and is an enlarged vertical cross-sectional view of part I in FIG. 2. The ballpoint pen tip 10 shown in FIG. 3 rotatably holds a ball 13 (writing element) within a ball holder 14 with the ball 13 partially protruding from the tip of an ink passage hole, which is a through-hole. A coil spring 18, which serves as a resilient member, is disposed behind the ball 13. The coil spring 18 is inserted from the rear of the ball holder 14 and pressed in so as to compress its entire length, preventing it from coming out. The restoring force resulting from this compression urges the ball 13 forward. The coil spring 18 is prevented from coming out by abutting the rear end of the coil spring 18 against the tip holder 11. Other methods of preventing the ball holder 14 from coming loose include forming a cut piece by broaching the rear inner wall surface of the ball holder 14, reducing the diameter of the rear end opening of the ball holder 14, or forming a convex portion on the inner wall surface by punching the side wall portion of the ball holder 14, and the method and shape of preventing the coil spring 18 from coming loose can be selected as appropriate.

[0019] When pressed against a writing surface such as paper, ball 13 moves backward, causing ink to flow out from a gap formed between ball 13 and ball holder 14 (described later) or to be transported outward and transferred as ball 13 rotates. The size of ball 13 can be 0.18 mm or more and 2.00 mm or less, the diameter of which is the same as that used in ordinary ballpoint pens. If the arithmetic mean height (Sa) of the surface of ball 13 is large, localized metal-to-metal contact between ball 13 and ball holder 14 is likely to occur, and the thick lubricating film containing phosphate ester and rubber elastic particles cannot be maintained at the contact area where localized high pressure occurs. Therefore, considering that the lubricating properties of the lubricating film can be more easily exhibited, the arithmetic mean height (Sa) of the surface of ball 13 is preferably 1.00 nm or more and 20.0 nm or less. The material of the ball 13 may be a cemented carbide alloy mainly composed of tungsten carbide, a metal such as stainless steel, aluminum, or iron, a ceramic such as silicon carbide, silicon nitride, titanium nitride, chromium carbide, alumina, or zirconia, a resin material such as polyethylene, polypropylene, polyacetal, or polyamide, or glass, but cemented carbide or ceramics are preferred in consideration of corrosion resistance by ink.

[0020] Next, details of the ballpoint pen tip 10 are described in FIG. 4, an enlarged view of portion II in FIG. 3. The ball holder 14 has a through-hole ink passage hole. This ink passage hole includes a tip opening 19, which is crimped from the tip end to reduce its diameter, a ball holding portion 21 defined by an internal protrusion 20, in which the ball 13 is positioned with a portion protruding from the tip opening 19, a center hole 22 formed in the center of the internal protrusion 20, and a rear hole 23. The outer edge of the tip opening 19 may be curved to prevent it from getting caught on paper. The inner edge of the tip opening 19 is pressed against the ball 13 during crimping, transferring the curved surface of the ball 13 and polishing it to a mirror finish, in order to improve sealing when the ball 13 is pressed against the ball 13 and comes into circumferential contact with the coil spring 18. Additionally, multiple ink passage grooves 24 are formed radially and equidistantly in the inward protrusion 20 by cutting. This ink passage groove 24 opens partway into the center hole 22 without passing through the rear hole 23, but it may also pass through the rear hole 23 to ensure ink supply to the ball holding portion 21. A concave ball receiving seat 25 is formed by pressing the ball 13 against the inward protruding portion 20. This ball receiving seat 25 stabilizes the position of the ball 13 when it comes into contact with the paper surface or the like and retracts during writing, ensuring smooth rotation with little unnecessary vibration, and is shaped so that the ball 13 and ball receiving seat 25 come into approximate planar contact. The ink passage groove 24 has an opening outside the ball receiving seat 25 formed in the inward protruding portion 20, ensuring ink supply to the ball holding portion 21.

[0021] The diameter A of the ball 13 of the ballpoint pen tip 10 is preferably 0.18 mm or more and 2.00 mm or less. The dimensional values ​​of the ballpoint pen tip 10 are as follows: the inner diameter B of the tip opening 19 is 80% or more and 98% or less of the diameter of the ball 13; the forward / backward movement distance C of the ball 13 is 2% or more and 10% or less of the diameter A of the ball 13; the ball protrusion length D is 20% or more and 35% or less of the diameter A of the ball 13; the maximum inner diameter E of the ball holding portion 21 is 100% or more and 130% or less of the diameter A of the ball 13; the number of ink channels 24 is 2 or more and 6 or less; and the width F of the ink channels 24 is 0.05 mm. The ink passage groove 24 has a depth G of 0.10 mm or greater or may extend from the ball holding portion 21 to the rear hole 23. The ball receiving seat diameter H is 65% to 95% of the diameter A of the ball 13. The central hole diameter I is 40% to 70% of the diameter A of the ball 13. The seat angle α of the ball holding portion 21 is preferably 90 degrees to 160 degrees, the crimping angle β is 50 degrees to 90 degrees, the chamfer angle γ is 20 degrees to 60 degrees, and the taper angle δ is 150 degrees or less. Furthermore, the surface of the ballpoint pen tip 10 is preferably treated with either a hydrophilic or hydrophobic treatment depending on the ink used, since this prevents ink from adhering to the ballpoint pen tip 10. The dimensions of each part are shown in Figures 4, 5, and 6 (the ball 13 and coil spring 18 are not shown).

[0022] In some embodiments, the ratio C / A of the amount of forward and backward movement C of ball 13 to the diameter A of ball 13 may be 5% or more and 10% or less. In this case, since the amount of forward and backward movement C of the ball is relatively large, the amount of ink ejected from the oil-based ballpoint pen can be increased, which tends to improve the writing feel.

[0023] In some embodiments, the crimping angle β of the tip of the ball holder 14 may be between 70 degrees and 90 degrees. In this case, since the crimping angle β is relatively large, the ink ejection amount of the oil-based ballpoint pen can be increased, and the writing feel tends to be good.

[0024] In some embodiments, the ratio E / A of the maximum inner diameter E of ball holding portion 21 to the ball diameter A may be 100% or more and 130% or less. In this case, since the maximum inner diameter E of ball holding portion 21 is relatively large, the ink ejection volume of the oil-based ballpoint pen can be increased, and the writing feel is likely to be good.

[0025] In some embodiments, the ratio H / A of the diameter H of the ball receiving seat 25 to the diameter A of the ball may be 70% or more and 95% or less. In this case, since the diameter H of the ball receiving seat 25 is relatively large, it is easy to suppress blobbing even if the ink ejection amount is large.

[0026] (Oil-based ink composition) The ink composition 15 filled in the ink reservoir 12 of the ballpoint pen refill 200 according to some embodiments is an oil-based ink composition described below.

[0027] An oil-based ink composition for a ballpoint pen according to some embodiments comprises a first phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group with a carbon number of 4 to 17, a second phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group with a carbon number of 18 to 24, water, and a nonionic surfactant.

[0028] According to the oil-based ink composition of the above-described embodiment, when writing with a ballpoint pen, a thick, water-containing multilayer film (hereinafter referred to as "multilayer film") containing a layer of phosphate ester and a layer of nonionic surfactant is likely to be formed between the ball at the pen tip and the metal surface of the receiving seat of the ball holder. That is, since the oil-based ink composition described above contains a first phosphate ester having a hydrocarbon group with a relatively small number of carbon atoms and a second phosphate ester having a hydrocarbon group with a relatively large number of carbon atoms, the phosphate groups of these phosphate esters are adsorbed to the metal surfaces of the ball and the receiving seat, forming a phosphate ester layer on the metal surfaces of the ball and the receiving seat. Here, since the second phosphate ester has a relatively long hydrocarbon group, a relatively thick phosphate ester layer is formed on the metal surface, and since the first phosphate ester has a relatively short hydrocarbon group, the second phosphate ester penetrates between the first phosphate esters, and a phosphate ester layer with a dense structure is quickly formed on the metal surface. The oil-based ink composition described above contains water and a nonionic surfactant. Therefore, when writing with a ballpoint pen, the hydrophobic group of the nonionic surfactant interacts with the hydrocarbon group of the phosphate ester, and a layer of the nonionic surfactant is formed between the layers of phosphate ester formed on the surfaces of the ball and the receiving seat, respectively, making it easy to obtain a thick multilayer film. Furthermore, the hydrophilic group of the nonionic surfactant interacts with water, and water with high surface tension is taken up by the nonionic surfactant layer, thereby improving the cushioning properties of the multilayer film. According to the above-described embodiment, when writing with a ballpoint pen, a multilayer film with a large thickness and excellent cushioning properties is easily formed between the ball and the metal surface of the receiving seat, and the multilayer film can be maintained between the ball and the receiving seat even when writing at high speed or with high writing pressure, resulting in good lubrication during writing. This results in a good writing feel even when writing at high speed or with high writing pressure, and can prevent smearing, skipped lines, or blobbing. In addition, in the above-described embodiment, the nonionic surfactant does not tend to wet and spread on areas where there is no metal, and therefore excessive wetting and spreading of the phosphate ester that interacts with the nonionic surfactant is suppressed, thereby effectively suppressing leakage of the ink composition from the pen tip. Therefore, according to the above-described embodiment, ink leakage can be effectively suppressed, and good handwriting can be obtained with a good writing feel even when writing at high speed or with high writing pressure.

[0029] In this specification, "smeared" refers to a state in which the ball of a ballpoint pen does not rotate and ink is not transferred. It also includes a state in which the ink becomes thicker over time and is no longer ejected. In addition, in this specification, "skipped lines" refers to a state in which the lubrication between the ball of a ballpoint pen and the receiving seat of the ball holder is poor, causing the ball to rotate intermittently and resulting in intermittent transfer of ink.

[0030] The first phosphate ester and the second phosphate ester, which are polyoxyethylene hydrocarbon phosphate esters having a hydrocarbon group, may be monoesters, diesters, or triesters, or may be mixtures thereof. When the polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group is a monoester, it is represented by the following formula (A): RO-(CH2CH2O) n -PO(OH)2…(A)

[0031] The first phosphate ester has a hydrocarbon group (R in the above formula (A)) with 4 or more and 17 or less carbon atoms. The second phosphate ester has a hydrocarbon group (R in the above formula (A)) with 18 or more and 24 or less carbon atoms.

[0032] The hydrocarbon group of the phosphate ester may include a linear chain hydrocarbon group, a branched chain hydrocarbon group, or a cyclic hydrocarbon group. The chain hydrocarbon group or cyclic hydrocarbon group may be an unsaturated hydrocarbon group (such as an alkyl group) or an unsaturated hydrocarbon group (such as an alkenyl group, an alkynyl group, or a phenyl group).

[0033] The average number of moles of ethylene oxide added to the polyoxyethylene groups of the above-mentioned phosphate ester (the average value of n in the above formula (A)) is not particularly limited, but may be 2 or more and 10 or less, or 2 or more and 6 or less.

[0034] Specific examples of the first phosphate ester include a phosphate ester of polyoxyethylene tridecyl ether (hydrocarbon group: alkyl group having 13 carbon atoms), a phosphate ester of polyoxyethylene lauryl ether (hydrocarbon group: alkyl group having 12 carbon atoms), a phosphate ester of polyoxyethylene phenyl ether (hydrocarbon group: unsaturated hydrocarbon group having 13 carbon atoms), and a phosphate ester of polyoxyethylene lauryl ether (hydrocarbon group: alkyl group having 12 carbon atoms). Commercially available products include Phosphanol BH-650, Phosphanol SM-172, Phosphanol ED-200, Phosphanol GF-339, Phosphanol RA-600, Phosphanol GF-199, Phosphanol ML-200, Phosphanol ML-220, Phosphanol ML-240, Phosphanol RD-510Y, Phosphanol GF-185, Phosphanol RS-610, Phosphanol RS-710, Phosphanol RP-710, Phosphanol AK-25, Phosphanol GF-702, Phosphanol RS-610NA, Phosphanol SC-6103, Phosphanol LP-700, and Phosphanol LS-500 (all manufactured by Toho Chemical Industry Co., Ltd.), and Plysurf A207H, A208B, A219B, A208S, A212S, and A215C (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

[0035] The content of the first phosphate ester in the ink composition may be 0.2% by weight or more and 1.2% by weight or less, 0.3% by weight or more and 1.0% by weight or less, or 0.35% by weight or more and 0.6% by weight or less.

[0036] Specific examples of the second phosphate ester include, for example, a phosphate ester of polyoxyethylene oleyl ether (hydrocarbon group: unsaturated hydrocarbon group having 18 carbon atoms) and a phosphate ester of polyoxyethylene stearyl ether (hydrocarbon group: alkyl group having 18 carbon atoms). Examples of commercially available products include Phosphanol RL-210, RL-310, RB-410, RD-720, and LB-400 (all manufactured by Toho Chemical Industry Co., Ltd.).

[0037] The content of the second phosphate ester in the ink composition may be 0.05% by weight or more and 2.0% by weight or less, 0.1% by weight or more and 0.6% by weight or less, or 0.1% by weight or more and 0.3% by weight or less.

[0038] The difference between the number of carbon atoms in the hydrocarbon group of the second phosphate ester and the number of carbon atoms in the hydrocarbon group of the first phosphate ester may be 4 or more.

[0039] In this case, the difference between the number of carbon atoms in the hydrocarbon group of the second phosphate ester and the number of carbon atoms in the first phosphate ester is 4 or more, so the carbon chain lengths of the hydrocarbon groups of the two phosphate esters differ to some extent. Therefore, in the phosphate ester layer formed on the metal surface of the ball and the receiving seat, the second phosphate ester is more likely to penetrate between the first phosphate ester, making it easier for a densely structured phosphate ester layer to form on the metal surface. Therefore, when writing with a ballpoint pen, a thick multilayer film containing a phosphate ester layer and a nonionic surfactant layer is more likely to form between the ball at the pen tip and the metal surface of the receiving seat. This allows for a good writing feel and a clear handwriting, even when writing at high speed or with high writing pressure.

[0040] In some embodiments, the hydrocarbon group of the first phosphate ester has 12 to 14 carbon atoms, and the hydrocarbon group of the second phosphate ester has 18 to 20 carbon atoms.

[0041] In the above-described embodiment, the hydrocarbon group of the first phosphate ester has a carbon number of 12 to 14, and the hydrocarbon group of the second phosphate ester has a carbon number of 18 to 20, so the carbon chain lengths of the two hydrocarbon groups differ to some extent. Therefore, in the phosphate ester layer formed on the metal surface of the ball and the receiving seat, the second phosphate ester is more likely to penetrate between the first phosphate ester, making it easier to form a densely structured phosphate ester layer on the metal surface. Therefore, when writing with a ballpoint pen, a thick multilayer film including a phosphate ester layer and a nonionic surfactant layer is more likely to form between the ball at the pen tip and the metal surface of the receiving seat. This allows for a good writing feel and a clear handwriting, even when writing at high speed or with high writing pressure.

[0042] In some embodiments, the HLB value of the first phosphate ester and the HLB value of the second phosphate ester may be 4 or greater and 14 or less, or 7 or greater and 12 or less.

[0043] In this specification, the HLB (Hydrophilic-Lipophilic Balance) value refers to the HLB value calculated by the Davis method. The HLB value indicates the affinity for water and oil, with a higher value indicating a higher affinity for water.

[0044] In the above-described embodiment, the HLB values ​​of the first phosphate ester and the second phosphate ester are 4 or greater or 7 or greater, providing moderate hydrophilicity and thus less likely to inhibit water uptake into the multilayer film. Furthermore, in the above-described embodiment, the HLB values ​​of the first phosphate ester and the second phosphate ester are 14 or less or 12 or less, making it easier for the hydrocarbon groups of the first and second phosphate esters to interact with the hydrophobic groups of the nonionic surfactant. As a result, the hydrophilic groups of the nonionic surfactant interact more easily with water, facilitating water uptake into the nonionic surfactant layer. Therefore, according to the above-described embodiment, water is more easily retained in the nonionic surfactant layer, enhancing the cushioning properties of the multilayer film formed between the ball and the metal surface of the receiving seat. Therefore, even when writing at high speed or with high writing pressure, the multilayer film is more easily retained between the ball and the receiving seat, providing good lubrication during writing. This makes it easier to achieve a good writing feel and handwriting, even when writing at high speed or with high writing pressure.

[0045] In some embodiments, the total content of the first phosphate ester and the second phosphate ester in the ink composition is 0.4% by weight or more and 3.0% by weight or less.

[0046] According to the above-described embodiment, the total content of the first phosphate ester and the second phosphate ester is 0.4% by weight or more and 3.0% by weight or less, so that the density of the phosphate ester layer formed on the metal surface of the ball and the receiving seat is appropriate, and therefore a multilayer film of appropriate density is formed between the ball of the pen tip and the metal surface of the receiving seat. This makes it possible to effectively suppress ink leakage while also making it easier to obtain a good writing feel and handwriting even when writing at high speed or with high writing pressure.

[0047] In some embodiments, the weight-based ratio of the content of the first phosphate ester to the content of the second phosphate ester (content of the first phosphate ester [wt %] / content of the second phosphate ester [wt %]) may be 0.2 or more and 8.0 or less, or may be 0.25 or more and 4.0 or less.

[0048] According to the above-described embodiment, the weight ratio of the content of the first phosphate ester to the content of the second phosphate ester is 0.2 to 8.0 or 0.25 to 4.0, so that the phosphate ester layer formed on the metal surface tends to have a dense structure. As a result, a multilayer film of appropriate density is formed between the ball of the pen tip and the metal surface of the holder. This effectively prevents ink leakage and makes it easier to achieve a good writing feel and handwriting even when writing at high speed or with high writing pressure.

[0049] The nonionic surfactant may be any well-known nonionic surfactant without any particular limitation, including ester-type nonionic surfactants such as esters of polyhydric alcohols and fatty acids, ether-type nonionic surfactants such as polyoxyethylene hydrocarbon ethers and polyoxyethylene hydrocarbon phenyl ethers, and ester-ether-type nonionic surfactants having both ester and ether bonds in the molecule.

[0050] The content of the nonionic surfactant in the ink composition may be 0.25% by weight or more and 2.0% by weight or less, or may be 0.5% by weight or more and 1.0% by weight or less.

[0051] In some embodiments, the nonionic surfactant has an HLB value of 4 or more and 15 or less.

[0052] In the above-described embodiment, the nonionic surfactant has an HLB value of 4 or higher, which means that it is hydrophilic to a certain extent, and thus interacts with water, making it easy for water to be absorbed into the nonionic surfactant layer. Furthermore, in the above-described embodiment, the nonionic surfactant has an HLB value of 15 or lower, which means that it is not excessively hydrophilic and easily interacts with the hydrocarbon groups of the first and second phosphate esters, making it easy to form the above-described multilayer film between the ball and the metal surface of the receiving seat. Therefore, according to the above-described embodiment, ink leakage can be effectively suppressed, while a good writing feel and handwriting can be easily obtained even when writing at high speed or with high writing pressure.

[0053] Specific examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyoleyl ether, polyoxyethylene hydrogenated castor oil, sorbitan sesquioleate, polyoxyethylene sorbitan monooleate, and polyglycerin fatty acid decaglyceryl. Commercially available products: としては, NIKKOL BL-2, same as BL-4.2, same as BL-9EX, same as BC-2, same as BC-5.5, same as BC-7, same as BC-10, same as BS-2, same as BS-4, same as BO-2V, same as BO-7V, same as BO-10V, same as BB-5, same as BB-10, same as BD-4 , same as BT-3, same as BT-5, same as BT-7, same as BT-9, same as BT-12, same as PBC-31, same as PBC-33, same as PBC-41, same as PBC-44, same as PEN-4612, same as PEN-4620, same as PEN-4630, same as BPS-5 Same as BPS-10, same as HCO-5, same as HCO-10, same as HCO-20, same as HCO-30, same as HCO-40, same as HCO-50, same as HCO-60, same as HCO-80, same as TS-10V, same as TS-10MV, same as TS-106V, same as TS-30V, same as TI-10V, same as TO-10V, same as TO-10MV, same as TO-106V, same as TO-30V, same as GS-460, same as GO-4V, same as GO-430NV, same as GO-440V, same as GO-460V, same as Tetraglyn 1-SV, same as Tetraglyn 1-OV, same as Hexaglyn 1-L, same as Hexaglyn 1-M, same as Hexaglyn 1-SV, same as Hexaglyn 1-OV, same as Decaglyn 1-M, same as Decaglyn 1-SV, same as Decaglyn 1-50SV, same as Decaglyn 1-ISV, same as Decaglyn 1-OV, same as Decaglyn 1-LN, same as Decaglyn 2-SV, same as Decaglyn 2-ISV, same as Decaglyn 3-SV, same as Decaglyn 3-OV, same as TMGS-5V, same as TMGS-15V, same as TMGO-5, same as TMGO-15 (and above, manufactured by Nikko Kemikazu Co., Ltd.), Pegon L-4, same as TH-8, same as L-9A, same as L-12S, same as T-6, same as TE-10A, same as ST-7, same as ST-9, same as ST-12, same as O-6S, same as O-16A, same as S-4DV (and above, Made by Toho Chemical Industry Co., Ltd.), ノイゲンXL-40, same as XL-100, same as TDS-30, LF-60X, same as TDX-50, same as TDX-80, same as SD-30, same as S D-60, same as SD-70, same as SD-80, same as EA-87, same as ソルゲン90, same as 110, same as TW-60 (above, made by Daiichi Industrial Co., Ltd.) をげることができる.

[0054] The water in the ink composition may be mineral water, tap water, ion-exchanged water, purified water, distilled water, or pure water.

[0055] In some embodiments, the water content in the ink composition may be 1.0% by weight or more and 10.0% by weight or less, or 4.0% by weight or more and 8.0% by weight or less.

[0056] In the above-described embodiment, the water content in the ink composition is 1.0 wt% or more or 4.0 wt% or more, so that a certain amount of water is incorporated into the multilayer film, thereby enhancing the cushioning properties of the multilayer film. Furthermore, in the above-described embodiment, the water content in the ink composition is 10.0 wt% or less or 8.0 wt% or less, so that the water content in the oil-based ink composition is not too high, allowing water to dissolve stably in the oil-based ink. The method for adding water is not particularly limited. For example, water may be added directly to an ink containing an appropriate mixture of components other than water, or water may be added to components used in ballpoint pen oil-based inks, such as colorants and resins, after they have absorbed moisture or water.

[0057] In the oil-based ink for ballpoint pens according to some embodiments, the colorant is not particularly limited and may be a water-based dye, an oil-soluble dye, or a pigment.

[0058] As the water-soluble dye, specifically, any of direct dyes, acid dyes, basic dyes, etc. can be used. Specific examples of direct dyes include Japanol Fast Black D Concentrate (CI Direct Black 17), Water Black 100L (19), Water Black L-200 (19), Direct Fast Black B (22), Direct Fast Black AB (32), Direct Deep Black EX (38), Direct Fast Black Concentrate (51), Kayalas Spragray VGN (71), Kayalas Direct Brilliant Yellow G (CI Direct Yellow 4), Direct Fast Yellow 5GL (26), Aizen Primula Yellow GCLH (44), Direct Fast Yellow R (50), Aizen Direct Fast Red FH (CI Direct Red 1), Nippon Fast Scarlet GSX (4), Direct Fast Scarlet 4BS (23), Aizen Direct Rhoduline BH (same 31), Direct Scarlet B (same 37), Kayak Direct Scarlet 3B (same 39), Aizen Primula Pink 2BLH (same 75), Sumi Light Red F3B (same 80), Aizen Primula Red 4BH (same 81), Kayalas Sprat Vin BL (same 83), Kayalas Light Red F5G (same 225), Kayalas Light Red F5B (same 226), Kayalas Light Rose FR (same 2 27), Direct Sky Blue 6B (CI Direct Blue 1), Direct Sky Blue 5B (same 15), Sumilite Splat Blue BRR Concentrate (same 71), Daibogen Turquoise Blue S (same 86), Water Blue #3 (same 86), Kayalas Turquoise Blue GL (same 86), Kayalas Splat Blue FF2 GL (same 106), Kayalas Splat Turquoise Blue FBL (same 199), etc.

[0059] Specific examples of acid dyes include Acid Blue Black 10B (CI Acid Black 1), Nigrosine (same 2), Suminol Milling Black 8BX (same 24), Kayanol Milling Black VLG (same 26), Suminol Fast Black BR ​​Concentrate (same 31), Mitsui Nylon Black GL (same 52), Aizen Opal Black WH Extra Concentrate (same 52), Sumiran Black WA (same 52), Ranil Black BG Extra Concentrate (same 107), Kayanol Milling Black TLB (same 109), Suminol Milling Black B (same 109), Kayanol Milling Black TLR (same 110), Aizen Opal Black New Concentrate (same 119), Water Black 187-L (same 154), Kayaku Acid Brilliant Flavin FF (CI Acid Yellow 7:1), Kayasil Yellow GG (same 17) , Xylene Light Yellow 2G 140% (same as 17), Suminol Leveling Yellow NR (same as 19), Daiwa Tartrazine (same as 23), Kayak Tartrazine (same as 23), Suminol Fast Yellow R (same as 25), Diacid Light Yellow 2GP (same as 29), Suminol Milling Yellow O (same as 38), Suminol Milling Yellow MR (same as 42), Water Yellow #6 (same as 42), Kayanol Yellow NFG (same as 4 9), Suminol Milling Yellow 3G (same 72), Suminol Fast Yellow G (same 61), Suminol Milling Yellow G (same 78), Kayanol Yellow N 5G (same 110), Suminol Milling Yellow 4G 200% (same 141), Kayanol Yellow NG (same 135), Kayanol Milling Yellow 5GW (same 127), Kayanol Milling Yellow 6GW (same 142), Sumitomo Fast Scarlet A (CIAcid Red 8), Kayaku Silk Scarlet (9), Solar Rubin Extra (14), Daiwa New Kokushin (18), Aizen Bonsaw RH (26), Daiwa Red No. 2 (27), Suminol Leveling Brilliant Red S3B (35), Kayasil Rubinol 3GS (37), Aizen Erythrosine (51), Kayaku Acid Rhodamine FB (52), Suminol Leveling Rubinol 3GP (57), Diacid Alizarin Rubinol F3G 200% (82), Aizen Eosin GH (87), Water Pink #2 (92), Aizen Acid Phloxine PB (92), Rose Bengal (94), Kayanolumi Ring Scarlet FGW (same as 111), Kayanol Milling Rubin 3BW (same as 129), Sumino All Milling Brilliant Red 3BN Concentrate (same as 131), Sumino All Milling Brilliant Red BS (same as 138), Eisen Opal Pink BH (same as 186), Sumino All Milling Brilliant Red B Concentrate (same as 249), Kayaku Acid Brilliant Red 3BL (same as 254), Kayaku Acid Brilliant Red BL (same as 265), Kayanol Milling Red GW (same as 276), Mitsui Acid Violet 6BN (CI Acid Violet 15), Mitsui Acid Violet BN (same as 17), Sumitomo Patent Pure Blue VX (CIAcid Blue 1), Water Blue #106 (same 1), Patent Blue AF (same 7), Water Blue #9 (same 9), Daiwa Blue No. 1 (same 9), Supranol Blue B (same 15), Orient Soluble Blue OBC (same 22), Suminol Leveling Blue 4GL (same 23), Mitsui Nylon Fast Blue G (same 25), Kayasil Blue AGG (same 40), Kayasil Blue BR (same 41), Mitsui Alizarin Sapphirol SE (same 43), Suminol Leveling Sky Blue R Extra Conc (same 62), Mitsui Nylon Fast Sky Blue B (same 78), Sumitomo Brilliant Indocyanine 6B Examples include h / c (83), Sandran Cyanine N-6B 350% (90), Water Blue #115 (90), Orient Soluble Blue OBB (93), Sumitomo Brilliant Blue 5G (103), Kayanol Milling Ultra Sky SE (112), Kayanol Milling Cyanine 5R (113), Aizen Opal Blue 2 GLH (158), Daiwa Guinea Green B (CI Acid Green 3), Acid Brilliant Milling Green B (9), Daiwa Green #70 (16), Kayanol Cyanine Green G (25), and Suminol Milling Green G (27).

[0060] Specific examples of basic dyes include Eisenkathiron Yellow 3GLH (CI Basic Yellow 11), Eisenkathiron Brilliant Yellow 5GLH (same 13), Sumiacrylic Yellow E-3RD (same 15), Maxiron Yellow 2RL (same 19), Astrazon Yellow 7GLL (same 21), Kayakryl Golden Yellow GL-ED (same 28), Astrazon Yellow 5GL (same 51), Eisenkathiron Orange GLH (CI Basic Orange 21), Eisenkathiron Brown 3GLH (same 30), Rhodamine 6GCP (CI Basic Red 1), Eisen Astraphloxine (same 12), Sumiacrylic Brilliant Red E-2B (same 15), and Examples include Strazon Red GTL (18), Eisen Katiron Brilliant Pink BGH (27), Maxilon Red GRL (46), Eisen Methyl Violet (CI Basic Violet 1), Eisen Crystal Violet (3), Eisen Rhodamine B (10), Astrazon Blue G (CI Basic Blue 1), Astrazon Blue BG (3), Methylene Blue (9), Maxilon Blue GRL (41), Eisen Katiron Blue BRLH (54), Eisen Diamond Green GH (CI Basic Green 1), Eisen Malachite Green (4), and Bismarck Brown G (CI Basic Brown 1). These may be used alone or in combination.

[0061] Specific examples of oil-soluble dyes that can be used include acid dyes, basic dyes, metal complex dyes, salt-forming dyes, azine dyes, anthraquinone dyes, phthalocyanine dyes, and triphenylmethane dyes. Specific examples include Nigrosine Base EE, Nigrosine Base EEL, Nigrosine Base EX, Nigrosine Base EXBP, Nigrosine Base EB, Oil Yellow 101, Nigrosine Base 107, Oil Pink 314, Oil Brown BB, Oil Green BG, Oil Blue 613, Oil Scarlet 308, Nigrosine Base BOS, Oil Black HBB, Oil Black 860, Oil Black BS, Barrifast Yellow 1101, Nigrosine Base 1105, Nigrosine Base 1108, Nigrosine Base 1109, Nigrosine Base 3104, Nigrosine Base 3105, Nigrosine Base 3108, Nigrosine Base 4120, Nigrosine Base AUM, Barrifast Orange 2210, Nigrosine Base 3209, Nigrosine Base 3210, Nigrosine Base 1306, Nigrosine Base 1308, Nigrosine Base 1320, Nigrosine Base 1364, Nigrosine Base 1355, Nigrosine Base 1366, Nigrosine Base 1367, Nigrosine Base 1370, Nigrosine Base 1371, Nigrosine Base 1372, Nigrosine Base 1373, Nigrosine Base 1374, Nigrosine Base 1375, Nigrosine Base 1376, Nigrosine Base 1377, Nigrosine Base 1378, Nigrosine Base 1379, Nigrosine Base 1380, Nigrosine Base 360, 2303, 2320, 3304, 3306, 3320, Balifast Pink 2310N, Balifast Brown 2402, 3405, Balifast Green 1501, Balifast Blue 1603, 1605, 1607, 1631, 2606, 2610, 2620, 2680, Balifast Violet 1701, 1702, 1731, Balifast Fast Black 1802, 1805, 1807, 3804, 3806, 3808, 3810, 3820, 3830, Spirit Red 102, Spirit Black AB, Ospi Yellow RY, ROB-B, MVB3, SP Blue 105 (all manufactured by Orient Chemical Industry Co., Ltd.), Aizen Spiron Yellow 3RH, Aizen Spiron GRLH Special, Aizen C-2GH, Aizen C-GNH New, Aizen Spiron Orange 2RH, GRH Concentrate Special, Aizen Spiron Red GEH, BEH, GRLH Special, C-GH, C-BH, Aizen Spiron Violet RH, C-RH, Aizen Spiron Brown BH Concentrate, RH, Aizen Spiron Mahogany RH, Aizen Spiron Blue GNH, 2BNH, C-RH, BPNH, Aizen Spiron Green C-GH, 3GNH Special, Aizen Spiron Black BNH, MH, RLH, GMH Special, BH Special, SBN Orange 703, SBN Violet 510, 521, SPT Orange 6, SPTBlue 111, SOT Pink 1, SOT Blue 4, SOT Black 1, SOT 6, SOT 10, SOT 12, SOT 13 Liquid, Eisen Rhodamine B Base, Eisen Methyl Violet Base, Eisen Victoria Blue B Base (all manufactured by Hodogaya Chemical Co., Ltd.), Oil Yellow CH, Oil Pink 330, Oil Blue 8B, Oil Black S, Eisen FS Special A, Eisen 2020, Eisen 109, Eisen 215, AL Yellow 1106D, Eisen 31 01, AL Red 2308, Neo Super Yellow C-131, C-132, C-134, Neo Super Orange C-233, Neo Super Red C-431, Neo Super Blue C-555, Neo Super Brown C-732, C-733 (all manufactured by Chuo Synthetic Chemical Industry Co., Ltd.), Oleosol Fast Yellow 2G, Oleosol Fast GCN, Oleosol Fast Orange GL, Oleosol Fast Red BL, Oleosol Fast RL (all manufactured by Taoka Chemical Industry Co., Ltd.) Sanovinyl Yellow 2GLS, Sanovinyl RLS, Sanovinyl 2RLS, Sanovinyl Orange RLS, Sanovinyl Fire Red GLS, Sanovinyl Red 3BLS, Sanovinyl Pink 6BLS, Sanovinyl Blue RN, Sanovinyl GLS, Sanovinyl Green 2GLS, Sanovinyl Brown GLS (all manufactured by Sandoz, Switzerland), Magenta SP 247%, Crystal Violet 10B 250%, Malachite Green Crystal Conc, Brilliant Green Crystal H 90%, Spirit Soluble Red 64843 (all manufactured by Holliday, UK), Neptune Red Base 543, Neptune Blue Base 634, Neptune Violet Base 604, Bassonil Red 540, Bassonil Violet 600, Victoria Blue F4R, Nigrosine Base LK (all manufactured by BASF, Germany), Methyl Violet 2B Base (all manufactured by National Anilne Div., USA). These may be used alone or in combination.

[0062] Specific pigments include carbon blacks such as Furnest Black, Contact Black, Thermal Black, and Acetylene Black, black iron oxide, yellow iron oxide, red iron oxide, ultramarine, Prussian blue, cobalt blue, titanium yellow, turquoise, molybdate orange, titanium oxide, gold powder, silver powder, copper powder, aluminum powder, brass powder, tin powder, mica pigments, and CIPIGMENT RED. 2, 3, 5, 17, 22, 38, 41, 48:2, 48:3, 49, 50:1, 53:1, 57:1, 58:2, 60, 63:1, 63:2, 64:1, 88, 112, 122, 123, 1 44, 146, 149, 166, 168, 170, 176, 177, 178, 179, 180, 185, 190, 194, 206, 207, 209, 216, 245, 254, CIPIGMENT ORANGE 5, 10, 13, 16, 36, 40, 43, CIPIGMENT Examples include VIOLET 19, 23, 31, 33, 36, 38, 50, CIPIGMENT BLUE 2, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 16, 17, 22, 25, 60, 66, CIPIGMENT BROWN 25, 26, CIPIGMENT YELLOW 1, 3, 12, 13, 24, 93, 94, 95, 97, 99, 108, 109, 110, 117, 120, 139, 153, 166, 167, 173, CIPIGMENT GREEN 7, 10, and 36. These can be used alone or in combination of two or more.

[0063] In addition to these pigments, processed pigments can also be used. Examples of such paints include Renol Yellow GG-HW30, HR-HW30, Orange RL-HW30, Red HF2B-HW30, FGR-HW30, F5RK-HW30, Carmine FBB-HW30, Violet RL-HW30, Blue B2G-HW30, CF-HW30, Green GG-HW30, Brown HFR-HW30, and Black R-HW30 (all manufactured by Clariant Japan Co., Ltd.), UTCO-001 Yellow, 012 Yellow, 021 Orange, 031 Red, 032 Red, 042 Violet, 051 Blue, 052 Blue, 061 Green, 591 Black, and 592 Black (all manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and MICROLITH Yellow. These include 4G-A, MX-A, 2R-A, Brown 5R-A, Scarlet RA, Red 2C-A, 3R-A, Magenta 2B-A, Violet BA, Blue 4G-A, and Green GA (all manufactured by Chiba Specialty Chemicals Co., Ltd.).

[0064] To improve the dispersibility of the pigment, anionic, cationic, nonionic, or amphoteric surfactants or polymer resins can be used as auxiliary agents. Specific examples include anionic, nonionic, or cationic surfactants such as higher fatty acids, higher alcohol sulfate ester salts, fatty acid sulfate ester salts, alkylarylsulfonic acids, phosphate esters, polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, and sorbitan fatty acid esters, as well as resins and oligomers for dispersing pigments, such as polyvinyl butyral resins, polyvinylpyrrolidone resins, polyacrylic acid ester resins, polymethacrylic acid ester resins, styrene-acrylic acid resins, and styrene-maleic acid resins. These may be used alone or in combination of two or more.

[0065] In some embodiments, the dispersion medium may be an organic solvent used in oil-based ballpoint pen inks. From the viewpoints of safety and odor, the organic solvent is preferably alcohol, glycol, or glycol ether.

[0066] Examples of organic solvents include ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, and triethylene glycol monomethyl ether. glycol ethers such as ethylene glycol, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol tertiary butyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, 3-methyl-3-methoxy-1-butyl acetate, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, octylene glycol,Examples of suitable esters include glycols such as glycerin, polyethylene glycol, 3-methyl-1,3-butanediol, 1,3-propanediol, 1,3-butanediol, and 1,5-pentanediol; alcohols such as benzyl alcohol, β-phenylethyl alcohol, α-methylbenzyl alcohol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methyl-3-methoxy-1-butanol, 3-methyl-3-methoxypentanol, lauryl alcohol, tridecyl alcohol, isodecyl alcohol, and isotridecyl alcohol; ethers such as methyl isopropyl ether, ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether, butyl ether, hexyl ether, and 2-ethylhexyl ether; and esters such as 2-ethylhexyl acetate, isobutyl isobutyrate, ethyl lactate, and butyl lactate. Considering the improvement in writing feel due to the lower viscosity and the resistance of the pen tip to drying, it is preferable to use a low-boiling organic solvent selected from alcohols, glycols, and glycol ethers having a boiling point of 80°C to 200°C inclusive, in combination with a high-boiling organic solvent having a boiling point of over 200°C. The weight ratio of low-boiling organic solvent / high-boiling organic solvent is preferably 1.0 to 30.0, and more preferably 1.3 to 6.0.

[0067] The ink composition according to some embodiments may optionally contain anti-leakage particles to prevent leakage of the ink. Specific examples of the leakage prevention particles include silica particles, titanium oxide, silicone resin particles, silicone rubber particles, and silicone composite particles.

[0068] In particular, silicone composite particles have a structure in which silicone rubber particles are coated with silicone resin. The low cohesion properties due to the low intermolecular forces and low adhesiveness of the silicone resin, combined with the elasticity of the silicone rubber within the silicone composite particles, have a synergistic effect, allowing them to function without breaking when writing and without forming an aggregated structure even in areas where the ink flow path narrows, and it is thought that this makes it possible to suppress ink leakage even in dry environments with low humidity.

[0069] When the leakage prevention particles are added to the ink, they may be added directly or in the form of a dispersion in advance.

[0070] The ink composition according to some embodiments may include a dispersant for dispersing particles such as the leakage prevention particles described above. Examples of the dispersant include a dispersing resin and an activator, such as a polybutyral resin, a polymer having an acidic group, an acrylic copolymer, a phosphoric acid copolymer, a phosphoric acid polyester, an alkylol ammonium salt of a copolymer containing an acidic group, a carboxylic acid ester having a hydroxyl group, and a nonionic activator.

[0071] It is preferable to use polyvinyl butyral as the dispersant, and it is even more preferable to use a dispersant with an acid value of 60 mgKOH / g or more in combination, as this improves the dispersion stability of the silicone composite particles and provides long-term storage stability. Specific examples of polyvinyl butyral include S-LEC BL-1, BL-1H, BL-2, BL-2H, BL-5, BL-10, BL-S, BX-L, BM-1, BM-2, BM-5, BM-S, BH-3, BH-6, BH-S, BX-1, BX-5, KS-10, KS-1, KS-3, and KS-5 (all manufactured by Sekisui Chemical Co., Ltd.), Mowital B 14 S, B 16 H, B 20 H, B 30 T, B 30 H, B 30 HH, B 45 H, B 60 T, B 60 H, B 60 HH, and B 75 H. (All manufactured by Kuraray Co., Ltd.) Specific examples of dispersants with an acid value of 100 mg KOH / g or more include DISPERBYK-102 (acid value 101 mg KOH / g), DISPERBYK-106 (acid value 132 mg KOH / g, amine value 74 mg KOH / g), DISPERBYK-111 (acid value 129 mg KOH / g), DISPERBYK-140 (acid value 73 mg KOH / g, amine value 76 mg KOH / g), DISPERBYK-145 (acid value 76 mg KOH / g), g, amine value 71 mg KOH / g), BYK-180 (acid value 94 mg KOH / g, amine value 94 mg KOH / g), BYK-P104 (acid value 180 mg KOH / g), BYK-P104S (acid value 150 mg KOH / g), BYK-P105 (acid value 365 mg KOH / g), BYK-220S (acid value 100 mg KOH / g), W9011 (acid value 65 mg KOH / g) and above, all manufactured by BYK Japan Co., Ltd. The amine value expressed here is expressed as the number of milligrams (mg) of potassium hydroxide (KOH) equivalent to the amount of hydrochloric acid required to neutralize the primary, secondary, and tertiary amines contained in 1 g of sample.

[0072] The dispersants can be used alone or in combination, and are preferably used in an amount of 5% by weight to 200% by weight relative to the leakage prevention particles (silicone composite particles, etc.).

[0073] The leakage prevention particles (e.g., silicone composite particles) can be dispersed in the ink composition by a conventional method. For example, the leakage prevention particles (e.g., silicone composite particles), a solvent, and a dispersant are mixed and uniformly stirred using a propeller stirrer or the like, and then the leakage prevention particles (e.g., silicone composite particles) are dispersed using a disperser. The disperser is appropriately selected from among kneaders, roll mills, ball mills, sand mills, bead mills, Henschel mixers, homogenizers, high-pressure homogenizers, thin-film swirling high-speed mixers, etc., depending on the amount of solvent in the ink and the pigment concentration. In particular, dispersion using a thin film rotary high speed mixer, Filmix (manufactured by Primix Corporation), is preferred from the viewpoint of enhancing the storage stability of the dispersion.

[0074] In some embodiments, the ink composition may contain a resin for the purposes of adjusting the viscosity of the ink and improving the fixation of handwriting.

[0075] Specific examples of the resins include polyvinylpyrrolidone resin, polyvinyl alcohol resin, polyvinyl butyral resin, ketone resin, acrylic acid-acrylic acid ester resin, acrylic acid-methacrylic acid ester resin, methacrylic acid-acrylic acid ester resin, methacrylic acid-methacrylic acid ester resin, styrene-acrylic acid resin, styrene-maleic acid resin, phenolic resin, rosin, rosin ester, modified rosin, modified rosin ester, maleated rosin, maleated rosin ester, fumarated rosin, fumarated rosin ester, cellulose derivatives such as carboxymethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and hydroxypropyl cellulose, synthetic polymers such as N-vinylacetamide polymer crosslinked products, and inorganic clay minerals.Specific examples of resins that can be used include S-LEC BL-1, BL-1H, BL-2, BL-2H, BL-5, BL-10, BL-S, BX-L, BM-1, BM-2, BM-5, BM-S, BH-3, BH-6, BH-S, BX-1, BX-5, KS-10, KS-1, KS-3, and KS-5 (all manufactured by Sekisui Chemical Co., Ltd.), Mowital B 14 S, B 16 H, B 20 H, B 30 T, B 30 H, B 30 HH, B 45 H, B 60 T, B 60 H, B 60 HH, and B 75 H (all manufactured by Kuraray Co., Ltd.), and polyvinylpyrrolidone. K-30, K-85, K-90 (all manufactured by Nippon Shokubai Co., Ltd.), PVP K-15, K-30, K-60, K-90, K-120 (all manufactured by ISP Japan Co., Ltd.), GE191-000, GE191-053, GE191-103, GE191-104, GE191-107, GE191-405 (manufactured by Resonac Co., Ltd.), Tamanol 100S, Tamanol 510 (all manufactured by Arakawa Chemical Industries Co., Ltd.), Hitanol 1501, Hitanol 2501 (all manufactured by NOF Corporation), YP-90, YP-90L, YS Polystar S145, YS Polystar #2100, YS Polystar #2115, YS Polystar #2130, YS Polystar T80, YS Polystar T100, YS Polystar T115, YS Polystar T130, YS Polystar T145, Mighty Ace G125, Mighty Ace G150 (all manufactured by Yasuhara Chemical Co., Ltd.), TEGO Examples include Variplus SK, EP-1201 TF, TC, CA, AP, EP-UC, DS 50, UC W 40, and 3350 UV (manufactured by Evonik Japan Co., Ltd.). These may be used alone or in combination of two or more.

[0076] In some embodiments, a resin having an acidic group may be used as the resin. By using a resin having an acidic group as the resin, the apparent bulkiness increases due to electrostatic adsorption to the leakage prevention particles (such as silicone composite particles), preventing collisions between the leakage prevention particles (such as silicone composite particles), improving dispersion stability, and also quickly loosening the silicone composite particles that acted as a sealant when rewriting after writing, reducing smearing at the start of writing (hereinafter referred to as "initial stroke smearing").

[0077] The degree of acidity of a resin is expressed by its acid value, which is the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize all the acidic components contained in 1 g of sample. An acid value of 50 mg KOH / g or more and 600 mg KOH / g or less is preferable, and an acid value of 150 mg KOH / g or more and 550 mg KOH / g or less is even more preferable.

[0078] Furthermore, if the resin contains OH groups, the interaction with the acidic groups will improve the adsorption to the silicone composite particles, improving the lubricity and the writing feel. The amount of OH groups is expressed as an OH value, which is determined by acetylating with acetic anhydride, quantifying the free acetic acid with potassium hydroxide, and expressing it as the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize all the acidic components contained in 1 g of sample.

[0079] Specific examples of resins having acidic groups include rosins such as KR-612 (acid value 167 mg KOH / g) and KR-614 (acid value 175 mg KOH / g) (both manufactured by Arakawa Chemical Industries, Ltd.); maleic acid rosins such as Marquid No. 31 (acid value 188 mg KOH / g), No. 32 (acid value 130 mg KOH / g), No. 33 (acid value 305 mg KOH / g), and No. 3002 (acid value 100 mg KOH / g) (both manufactured by Arakawa Chemical Industries, Ltd.); and Harimac T-80 (acid value 185 mg KOH / g) (both manufactured by Harima Chemical Industries, Ltd.); and maleic acid rosin esters such as Hariestar. Examples of acid-modified rosins include MSR-4 (acid value 135 mg KOH / g) (both manufactured by Harima Chemicals Co., Ltd.), acid-modified rosins include KE-604 (acid value 238 mg KOH / g) and KR-120 (acid value 325 mg KOH / g) (both manufactured by Arakawa Chemical Industries, Ltd.), specially modified rosins include Haritack F-75 (acid value 145 mg KOH / g) and Haritack FG-90 (acid value 150 mg KOH / g) (both manufactured by Harima Chemicals Co., Ltd.), and styrene-acrylic acid resins include Joncryl 611 (acid value 53 mg KOH / g) and Joncryl 586 (acid value 108 mg KOH / g) (both manufactured by BASF Japan Ltd.).

[0080] In some embodiments, it is preferable to use a cellulose derivative, particularly hydroxypropyl cellulose, as the resin. The coexistence of silicone composite particles in the molecular network of hydroxypropyl cellulose not only provides a sealing effect in the ink flow path, but is also thought to be able to prevent the ink from spreading even when the pen tip is not retracted and is struck against a display, etc., as the hydroxypropyl cellulose and silicone composite particles are immediately oriented on the ink surface.

[0081] Specific examples include NISSO HPC-VH, H, M, L, SL, and SSL (all manufactured by Nippon Soda Co., Ltd.), and Klucel-H, M, G, J, L, and E (all manufactured by Ashland Japan Co., Ltd.).

[0082] The ink composition according to some embodiments may contain an amine as a pH adjuster. Specific examples include polyoxyethylene alkylamines such as AMIT 102, AMIT 105, AMIT 302, AMIT 308, and AMIT 320; fatty amines such as Farmin CS, Farmin 08D, Farmin 20D, Farmin 80, Farmin 86T, Farmin O, Farmin T, and Farmin (all manufactured by Kao Corporation); and Nymeen L-201, Nymeen L-202, Nymeen L207, Nymeen F-215, Nymeen S-202, Nymeen S-204, Nymeen S-210, Nymeen S-215, Nymeen S-220, Nymeen T2-206, and Nymeen T2-210. Examples of the amines include alkyl polyetheramines such as Nymeen T2-230, Nymeen T2-260, Nymeen DT-203, and Nymeen DT-208 (all manufactured by Nippon Oil & Fats Co., Ltd.), diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, triethylamine, dimethylaminoethanol, diethylaminoethanol, methyldiethanolamine, butyldiethanolamine, dibutylethanolamine, diethylisopropanolamine, butylisopropylamine, butylbenzylamine, and butoxypropylamine (all manufactured by Kanto Chemical Co., Ltd.). By maintaining the pH of the ink within an appropriate range, the adsorption of acidic substances to the metal ballpoint pen tip can be increased, preventing dotted lines in handwriting and improving the writing feel. The pH range of the ink composition is preferably 2.5 or more and 7.0 or less, and more preferably 3.5 or more and 6.0 or less.

[0083] The ink composition according to some embodiments may contain a rust inhibitor, such as benzotriazole.

[0084] The viscosity of the oil-based ink composition for ballpoint pens of the present invention is not particularly limited, but it is preferable that the ink viscosity at 25°C and a shear rate of 1.00 / sec be 30 mPa·s or more and 3000 mPa·s or less. If the viscosity is less than 30 mPa·s, the ink may bleed from the pen tip. If the viscosity exceeds 3000 mPa·s, the ink may have poor followability, resulting in poor handwriting smearing, i.e., initial smearing. Furthermore, the viscosity of the oil-based ink composition for ballpoint pens is preferably 30 mPa·s or more and 3000 mPa·s or less at 25°C and a shear rate of 100 / sec, which simulates writing. If the viscosity is less than 30 mPa·s, the lubricating film strength of the oil-based ink may be reduced, resulting in poor writing feel and poor wear resistance of the ball seat. If the viscosity exceeds 3000 mPa·s, the handwriting may smearing, i.e., initial smearing, when rewriting. The viscosity is more preferably 50 mPa·s or more and 500 mPa·s or less, and even more preferably 60 mPa·s or more and 200 mPa·s or less.

[0085] In some embodiments, an ink backflow preventer can be disposed at the ink interface in the ink reservoir tube to prevent unintended ink movement away from the pen tip and ink leakage from the rear opening of the ink reservoir tube due to such movement. When the ink backflow preventer is a liquid composition, a non-volatile and / or low-volatile liquid can be used. Specific examples include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or cooligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, and fatty acid-modified silicone oil. These non-volatile and / or low-volatile liquids may be used alone or in combination. The non-volatile and / or hardly-volatile liquid is preferably thickened to a suitable viscosity by adding a gelling agent. Examples of soluble gelling agents include clay-based thickeners such as hydrophobically treated silica, methylated silica, aluminum silicate, swellable mica, and hydrophobically treated bentonite or montmorillonite; fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate; tribenzylidene sorbitol; fatty acid amides; amide-modified polyethylene wax; hydrogenated castor oil; dextrin-based compounds such as fatty acid dextrin; and cellulose-based compounds. Among these, fatty acid metal soaps, fatty acid dextrins, and amide-modified polyethylene wax are preferred due to their excellent solvent resistance. Additionally, alcohol-based solvents, glycol-based solvents, surfactants, resins, metal oxide particles, etc., can be added to adjust gel strength and viscosity, prevent coloration of the backflow prevention body, and improve backflow prevention function. In addition, solids such as synthetic resin pillars called floats may be placed in the ink backflow prevention composition to narrow the apparent space in which the backflow prevention composition is placed, making it less likely to move due to external forces and improving impact resistance.

[0086] In some embodiments, the ballpoint pen 100 has a discharge amount of the oil-based ink composition of 0.04 g or more and 0.30 g or less per 100 m of writing distance when written on paper conforming to the specifications of test paper B defined in JIS S 6061: 2020 under writing conditions of a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec. In some embodiments, the discharge amount may be 0.04 g or more and 0.15 g or less, or may be 0.04 g or more and 0.08 g or less.

[0087] A large ink discharge volume of an oil-based ballpoint pen improves writing feel, but tends to cause bleed-through on the paper being written on. In this regard, the ballpoint pen 100 according to the above-described embodiment discharges a relatively large amount of ink composition per 100 m of writing distance under specific conditions: 0.04 g to 0.30 g, 0.04 g to 0.15 g, or 0.04 g to 0.08 g. While this discharge volume is relatively large for an oil-based ballpoint pen, the multilayer film formed between the ball 13 and the metal surface of the ball seat 25 is discharged from the pen tip and transferred to the paper surface during writing, thereby suppressing ink penetration into the paper. This allows for both a good writing feel and suppression of bleed-through. Therefore, while ink leakage can be effectively suppressed, a good writing feel and good handwriting can be obtained even when writing at high speed or with high writing pressure, and bleed-through can be suppressed.

[0088] The ballpoint pen 100 according to some embodiments is a paper (paper conforming to the specifications of test paper B specified in JIS S 6061:2020) on the front surface of which handwriting is formed by writing under the writing conditions of a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec. The L between the written portion and the non-written portion on the back surface of the paper is measured. * a * b * Color difference ΔE in color space * ab is 20.0 or less or 10.0 or less.

[0089] In this case, although the amount of ink composition discharged is relatively large for an oil-based ballpoint pen, the L between the written portion and the non-written portion on the back side of the paper on which the handwriting is formed is small. * a * b * Color difference ΔE in color space * ab is 20.0 or less or 10.0 or less, and bleed-through is suppressed. Therefore, it becomes easier to achieve both a good writing feel and suppression of bleed-through. [Example]

[0090] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0091] The viscosity in the examples was measured using an MCR302 (manufactured by Anton Paar) with a rotor CP50-1 at 25°C and shear rates of 1.00 / sec and 100 / sec (unit: mPa s).

[0092] The pH in the examples was measured at 25°C using Halo 2 (Hanna Instruments Japan).

[0093] As shown in Tables 1 to 10, oil-based ink compositions of Examples 1 to 32 and Comparative Examples 1 to 7 were prepared. The materials used are as follows. Tables 1 to 10 also show the content (wt%) of each material in the ink composition.

[0094] <Phosphate ester> Phosphate ester (1) (first phosphate ester): Phosphanol LS-500 (phosphate ester, a mixture of mono-, di-, and triesters of polyoxyethylene (4) tridecyl ether phosphate, HLB 9.0, manufactured by Toho Chemical Industry Co., Ltd.) C: 13 branched Phosphate ester (2) (first phosphate ester): Phosphanol GF-199 (phosphate ester, mixture of lauryl ether phosphate monoester, diester, and triester, HLB 5.5, manufactured by Toho Chemical Industry Co., Ltd.) C: 12 branched Phosphate ester (3) (first phosphate ester): Phosphanol RP-710 (phosphate ester, a mixture of mono-, di-, and triesters of polyoxyethylene (6) phenyl ether phosphate, HLB 11.9, manufactured by Toho Chemical Industry Co., Ltd.) C: 13 phenol Phosphate ester (4) (first phosphate ester): Plysurf A219B (phosphate ester, phosphate ester of polyoxyethylene lauryl ether, HLB 16.2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) C: 12 Phosphate ester (5) (second phosphate ester): Phosphanol LB-400 (phosphate ester, mixture of mono-, di-, and triesters of polyoxyethylene (4) oleyl ether phosphate, HLB 8.6, manufactured by Toho Chemical Industry Co., Ltd.) C: 18 unsaturated Phosphate ester (6) (second phosphate ester): Phosphanol RL-210 (phosphate ester, a mixture of phosphate ester, diester, and triester of polyoxyethylene (2) stearyl ether, HLB 5.4, manufactured by Toho Chemical Industry Co., Ltd.) C: 18 Phosphate ester (7): NIKKOL TOP-0V (trioleyl phosphate, manufactured by Nikko Chemicals Co., Ltd.)

[0095] <Water> Ion-exchanged water

[0096] <Surfactant> Surfactant (1) (nonionic surfactant): Pegnol ST-7 (polyoxyethylene (7) alkyl (C12-14) ether, HLB 12.8, manufactured by Toho Chemical Industry Co., Ltd.) Surfactant (2) (nonionic surfactant): NIKKOL BT-5 (polyoxyethylene alkyl (C12-14) ether, HLB 10.5, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (3) (nonionic surfactant): NIKKOL BT-12 (polyoxyethylene alkyl (C12-14) ether, HLB 14.5, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (4) (nonionic surfactant): NIKKOL BO-10V (polyoxyoleyl ether, HLB 14.5, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (5) (nonionic surfactant): NIKKOL BO-50V (polyoxyoleyl ether, HLB 18.0, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (6) (nonionic surfactant): NIKKOL BB5 (polyoxyethylene alkyl ether, HLB 7.0, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (7) (nonionic surfactant): NIKKOL HCO-20 (polyoxyethylene hydrogenated castor oil, HLB 10.5, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (8) (nonionic surfactant): Sorgen 30V (sorbitan sesquioleate, HLB 3.7, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Surfactant (9) (nonionic surfactant): NIKKOL TO-10V (polyoxyethylene sorbitan monooleate, HLB 15.0, manufactured by Nikko Chemicals Co., Ltd.) Surfactant (10) (nonionic surfactant): NIKKOL Decaglyn 1-ISV (polyglyceryl monoisostearate, HLB 15.0, manufactured by Nikko Chemicals Co., Ltd.)

[0097] <amine> Organic amine (1): Nymeen O-205 (polyoxyethylene oleylamine, NOF Corporation) Organic amine (2): Triisopropanolamine (Tokyo Chemical Industry Co., Ltd.) Organic amine (3): Triethanolamine (Tokyo Chemical Industry Co., Ltd.)

[0098] <Pigments> Pigment (1): Printex 35 (colorant, carbon black, manufactured by Orion Engineered Carbons Co., Ltd.) Pigment (2): FUJI FAST RED 8800 (colorant, CI Pigment Red 254, manufactured by Fuji Pigment Co., Ltd.) Pigment (3): CROMOPHTAL Blue A3R (colorant, CI Pigment Blue 60, manufactured by BASF Japan Ltd.)

[0099] <dye> Dye (1): SPILON RED C-GH (colorant, salt-forming dye of xanthene-based basic dye and alkyldiphenyl ether disulfonic acid, manufactured by Hodogaya Chemical Industry Co., Ltd.) Dye (2): VALIFAST RED 1364 (a salt-forming dye made from CI Basic Red 1:1, alkylbenzene sulfonic acid, and alkyldiphenyl ether disulfonic acid, manufactured by Orient Chemical Industries Co., Ltd.) Dye (3): SPILON YELLOW C-GNH new (colorant, a salt-forming dye of an indolinone-based basic dye and alkyldiphenyletherdisulfonic acid, manufactured by Hodogaya Chemical Industry Co., Ltd.) Dye (4): OIL BLUE 613 (colorant, mixture of CISolvent Blue 5 and rosin-modified resin, manufactured by Orient Chemical Industries Co., Ltd.) Dye (5): VALIFAST BLUE 1631 (a salt-forming dye made from CI Basic Blue 7 and a colorless organic acid, manufactured by Orient Chemical Industries Co., Ltd.) Dye (6): VALIFAST VIOLET 1731 (a salt-forming dye made from CI Acid Violet 17 and a methine dye, manufactured by Orient Chemical Industries Co., Ltd.)

[0100] <Solvent> Organic solvent (1): n-propanol Organic solvent (2): Ethylene glycol monoisopropyl ether Organic solvent (3): Ethylene glycol monophenyl ether Organic solvent (4): Benzyl alcohol

[0101] <Resin> Resin (1): S-LEC BL-1 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) Resin (2): S-LEC BH-3 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) Resin (3): PVPK-90 (Polyvinylpyrrolidone, manufactured by Ashland Japan Co., Ltd.) Resin (4): TEGO Variplus SK (polyol resin, OH value 325 mg KOH / g, Tg 90 ° C, manufactured by Evonik Japan Co., Ltd.) Resin (5): TEGO Variplus CA (ketone aldehyde condensation resin, OH value 200 mg KOH / g, Tg 75 ° C, manufactured by Evonik Japan Co., Ltd.) Resin (6): Marquid 3002 (maleic rosin, acid value 100 mg KOH / g, Tg 175°C, manufactured by Arakawa Chemical Industries, Ltd.) Resin (7): Harima T-80 (maleic rosin, acid value 185 mg KOH / g, Tg 85°C, manufactured by Harima Chemicals Co., Ltd.) Resin (8): 42% acrylic acid-acrylic and methacrylic acid ester copolymer in ethylene glycol monophenyl ether solution (solid equivalent acid value 510 mg KOH / g, OH value 130 mg KOH / g, Tg 80°C) Resin (9): 42% acrylic acid-styrene-methacrylic acid ester copolymer in ethylene glycol monophenyl ether solution (solid equivalent acid value 300 mg KOH / g, OH value 80 mg KOH / g, Tg 30°C) Resin (10): NISSO HPC-H (hydroxypropyl cellulose, weight average molecular weight: 1,000,000, manufactured by Nippon Soda Co., Ltd.) Resin (11): NISSO HPC-M (hydroxypropyl cellulose, weight average molecular weight: 700,000, manufactured by Nippon Soda Co., Ltd.) Resin (12): Metrose 65SH-1500 (weight average molecular weight: 216,600, hydroxypropyl methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0102] <Particle> Silicone composite particles (1): KMP-605 (silicone composite particles, average particle diameter 2 μm, rubber hardness 75 durometer A, true specific gravity 0.99 g / cm 3 , manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone composite particles (2): X-52-7030 (silicone composite particles, average particle diameter 0.8 μm, rubber hardness 75 durometer A, true specific gravity 1.01 g / cm 3 , manufactured by Shin-Etsu Chemical Co., Ltd.)

[0103] <Particle dispersant> Dispersant (1): DISPERBYK-102 (a copolymer having an acidic group, acid value 101 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (2): BYK-W9011 (copolymer with acidic groups, acid value 65 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (3): DISPERBYK-111 (copolymer containing acid groups, acid value 129 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (4): DISPERBYK-106 (polymer salt having an acid group, acid value 132 mg KOH / g, amine value 74 mg KOH / g, manufactured by BYK Japan Co., Ltd.)

[0104] <Rust inhibitor> Benzotriazole: Benzotriazole (manufactured by E-CHEM ENTERPRISE CORPORATION)

[0105] The procedure for preparing oil-based ink is as follows: an organic solvent or ion-exchanged water, phosphate ester, surfactant, colorant, and resin are stirred at 60°C with a propeller stirrer, and then other additives and, as appropriate, a cellulose derivative are added, either directly or after being uniformly dissolved or dispersed in a solvent with a propeller stirrer, and the mixture is stirred with a propeller for 2 hours to obtain the oil-based ink.

[0106] The ink backflow preventer 16 was prepared as follows: 50.0 wt.% Spectrasyn 100 (α-olefin oligomer, base material, Exxon Mobil Corporation, USA), 45.3 wt.% Lucant HC-100 (ethylene-α-olefin oligomer, base material, Mitsui Petrochemical Co., Ltd.), 3.50 wt.% Aerosil R972 (fine particle silica, gelling agent, Nippon Aerosil Co., Ltd.), and 1.20 wt.% Leopearl KL (dextrin fatty acid ester, Chiba Flour Milling Co., Ltd.) were mixed and stirred with a hot stirrer at 150°C for 2 hours to obtain a backflow preventer composition. The viscosity of this backflow preventer was 11,000 mPa·s at 25°C and a shear rate of 1.00 / sec, and 5,000 mPa·s at 25°C and a shear rate of 100 / sec.

[0107] (Creating an exam ballpoint pen)

[0108] Based on the ballpoint pen tip 10 shown in the figure, first to fifth ballpoint pen tips used in the test were produced with the following dimensions. The value in parentheses for each dimension is the ratio of that dimension to the diameter A of the ball 13 of the ballpoint pen tip 10. Each dimension is shown in Figures 4, 5, and 6 (the ball 13 and coil spring 18 are not shown). In Figure 5, the broken line shows the state in which the ball 13 is in contact with the ball transfer portion on the tip opening 19 side of the ball holder 14.

[0109] (First ballpoint pen tip) Diameter A of ball 13 = 0.5 mm The inner diameter B of the tip opening 19 is 0.48 mm (96% of the diameter A of the ball 13). The distance C of the ball 13 moving in the forward and backward direction is 0.03 mm (6% of the diameter A of the ball 13). Ball protrusion length D = 0.15 mm (30% of the diameter A of ball 13) The maximum inner diameter E of the ball holding portion 21 is 0.54 mm (108% of the diameter A of the ball 13) Number of 24 ink grooves = 5 Width of ink groove 24 F=0.09mm Depth G of ink passage groove 24 = 0.15 mm Ball seat diameter H = 0.44 mm (88% of diameter A of ball 13) Center hole diameter I = 0.28 mm (56% of diameter A of ball 13) Seat angle α of ball holding part 21: 105 degrees Crimping angle β=80° Chamfer angle γ=56° Taper angle δ=30° The wire diameter of the coil spring 18 is 0.14 mm. The pressing load on the ball 13 with the ring 18 disposed was set to 0.15N. The ball 13 used was a carbide ball PB-11 manufactured by Tsubaki Nakashima Co., Ltd., with a surface roughness, arithmetic mean height (Sa: ISO 25178), of 4.0 nm.

[0110] (Second ballpoint pen tip) Diameter A of ball 13 = 0.3 mm The inner diameter B of the tip opening 19 is 0.28 mm (93% of the diameter A of the ball 13). The distance C of the ball 13 moving in the forward and backward direction is 0.02 mm (7% of the diameter A of the ball 13). Ball protrusion length D = 0.08 mm (27% of the diameter A of ball 13) The maximum inner diameter E of the ball holding portion 21 is 0.34 mm (113% of the diameter A of the ball 13). Number of 24 ink grooves = 3 Width of ink groove 24 F=0.06mm Depth G of ink passage groove 24 = The ink passage groove 24 penetrates from the ball holding portion 21 to the rear hole 23. Seta Ball seat diameter H = 0.24 mm (80% of diameter A of ball 13) Center hole diameter I = 0.18 mm (60% of diameter A of ball 13) Seat angle α of ball holding part 21: 150 degrees Crimping angle β=80° Chamfer angle γ=56° Taper angle δ=30° The wire diameter of the coil spring 18 is 0.12 mm. The pressing load on the ball 13 with the ring 18 disposed was set to 0.15N. The ball 13 used was a carbide ball PB-11 manufactured by Tsubaki Nakashima Co., Ltd., with a surface roughness, arithmetic mean height (Sa: ISO 25178), of 1.8 nm.

[0111] (Third ballpoint pen tip) Diameter A of ball 13 = 0.4 mm The inner diameter B of the tip opening 19 is 0.38 mm (95% of the diameter A of the ball 13). The distance C of the ball 13 moving in the forward and backward direction is 0.03 mm (8% of the diameter A of the ball 13). Ball protrusion length D = 0.12 mm (30% of the diameter A of ball 13) The maximum inner diameter E of the ball holding portion 21 is 0.44 mm (110% of the diameter A of the ball 13) Number of 24 ink grooves = 3 Width of ink groove 24 F=0.08mm Depth G of ink passage groove 24 = The ink passage groove 24 penetrates from the ball holding portion 21 to the rear hole 23. Seta Ball seat diameter H = 0.33 mm (83% of diameter A of ball 13) Center hole diameter I = 0.23 mm (58% of diameter A of ball 13) Seat angle α of ball holding part 21: 130 degrees Crimping angle β=80° Chamfer angle γ=56° Taper angle δ=30° The wire diameter of the coil spring 18 is 0.12 mm. The pressing load on the ball 13 with the ring 18 disposed was set to 0.15N. Ball 13 is a carbide ball PB-11 manufactured by Tsubaki Nakashima Co., Ltd. The arithmetic mean height (Sa: ISO 25178) of the surface roughness was set to 1.8 nm.

[0112] (Fourth ballpoint pen tip) Diameter A of ball 13 = 0.7 mm The inner diameter B of the tip opening 19 is 0.68 mm (97% of the diameter A of the ball 13). The distance C of the ball 13 moving in the forward and backward direction is 0.04 mm (6% of the diameter A of the ball 13). Ball protrusion length D = 0.22 mm (31% of the diameter A of ball 13) The maximum inner diameter E of the ball holding portion 21 is 0.72 mm (103% of the diameter A of the ball 13) Number of 24 ink grooves = 5 Width of ink groove 24 F=0.10mm Depth G of ink passage groove 24 = 0.15 mm Ball seat diameter H = 0.57 mm (81% of ball 13 diameter A) Center hole diameter I = 0.35 mm (50% of diameter A of ball 13) Seat angle α of ball holding part 21: 120 degrees Crimping angle β=90° Chamfer angle γ=56° Taper angle δ=30° The wire diameter of the coil spring 18 is 0.14 mm. The pressing load on the ball 13 with the ring 18 disposed was set to 0.20N. The ball 13 used was a carbide ball PB-11 manufactured by Tsubaki Nakashima Co., Ltd., with a surface roughness, arithmetic mean height (Sa: ISO 25178), of 2.0 nm.

[0113] (Fifth ballpoint pen tip) Diameter A of ball 13 = 1.0 mm Inner diameter B of tip opening 19 = 0.95 mm (95% of diameter A of ball 13) The distance C of the ball 13 moving in the forward and backward direction is 0.05 mm (5% of the diameter A of the ball 13). Ball protrusion length D = 0.30 mm (30% of the diameter A of ball 13) The maximum inner diameter E of the ball holding portion 21 is 1.03 mm (106% of the diameter A of the ball 13). Number of 24 ink grooves = 5 Width of ink groove 24 F=0.12mm Depth G of ink passage groove 24 = 0.15 mm Ball seat diameter H = 0.86 mm (86% of diameter A of ball 13) Center hole diameter I = 0.50 mm (50% of diameter A of ball 13) Seat angle α of ball holding part 21: 110 degrees Crimping angle β=80° Chamfer angle γ=48° Taper angle δ=20° The wire diameter of the coil spring 18 was 0.15 mm, and the pressing load on the ball 13 when the coil spring 18 was disposed in the ball holder 14 was 0.30 N. The ball 13 used was a carbide ball PB-11 manufactured by Tsubaki Nakashima Co., Ltd., with a surface roughness, arithmetic mean height (Sa: ISO 25178), of 2.0 nm.

[0114] The arithmetic mean height, which is the surface roughness of the ball 13 in the examples, was measured at three locations in an arbitrary 20 (μm) x 20 (μm) area using a scanning probe microscope (AFM5100N; manufactured by Hitachi High-Tech Science Corporation) and calculated from the average value.

[0115] The ink compositions of Examples 1 to 32 and Comparative Examples 1 to 7 were filled into refills 200 based on the example shown in Fig. 2 and housed in exterior bodies 300 based on the example shown in Fig. 1 to obtain test sample ballpoint pens having the first to fifth ballpoint pen tips described above. The pen tips of the obtained ballpoint pens were sealed with packing (HM200, ethylene-vinyl acetate copolymer resin-based hot melt adhesive), and centrifugal force was applied to remove excess air bubbles so that the ink composition was distributed all the way to the pen tip.

[0116] (Discharge amount measurement) For each ink composition of the Examples and Comparative Examples, five test ballpoint pens each having one of the first to fifth ballpoint pen tips were prepared as described below. Using each test ballpoint pen, spiral writing was performed on paper conforming to the specifications of test paper B of JIS S 6061:2020 under the following conditions: a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec, in an environment of 25°C and 60% relative humidity. The mass of the ballpoint pen refill was measured using a precision balance before and after 100 m of writing, and the ink discharge volume (the difference in weight of the ballpoint pen refill before and after 100 m of writing) was obtained, and the average ink discharge volume of the five samples was calculated.

[0117] Test ballpoint pens were prepared and the discharge amounts were measured using a first ballpoint pen tip (ball diameter 0.5 mm) for Examples 1 to 12 and Comparative Examples 1 to 4, a second ballpoint pen tip (ball diameter 0.3 mm) for Examples 13 to 20 and Comparative Examples 5 and 6, a third ballpoint pen tip (ball diameter 0.4 mm) for Examples 21 to 26, a fourth ballpoint pen tip (ball diameter 0.7 mm) for Examples 27 to 29, and a fifth ballpoint pen tip (ball diameter 1.0 mm) for Examples 30 to 32. Comparative Example 7 was prepared using the tip of a ballpoint pen (Mat Hop, manufactured by Pentel Co., Ltd., ball diameter 1.0 mm) with a tip that provides a very high discharge amount.

[0118] The ink compositions of the examples and comparative examples were subjected to the following tests and evaluations. The evaluation results are shown in Tables 1 to 10.

[0119] (bleed-through confirmation test) For each example and comparative example, a test ballpoint pen that had undergone the above-described discharge amount measurement was used to write a 15 cm straight line on paper conforming to the specifications of test paper B of JIS S 6061:2020 under the conditions of a temperature of 25°C, a relative humidity of 60%, a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec. At a position 1 cm from the starting point of the resulting handwriting, a color difference (L * a * b *The measurement was carried out using a PIAS-II (manufactured by Quality Engineering Associates, Inc. (QEA)). The measurement range was 1 mm x writing width, and the L between the written area and the blank area (non-written area) was * a * b * Color difference ΔE in color space * ab The color difference ΔE was calculated. * ab The calculation method is as follows:

[0120]

number

[0121] The evaluation criteria for the resistance to strike-through are as follows: A:ΔE * ab is between 0 and 10.0 B:ΔE * ab is greater than 10.0 and less than or equal to 20.0 C:ΔE * ab is greater than 20.0 and less than or equal to 40.0 D:ΔE * ab is greater than 40.0

[0122] (Writing feel) Three test ballpoint pens having the first ballpoint pen tip were prepared for each Example and Comparative Example, and after removing the packing, handwriting was carried out on paper conforming to the specifications of test paper A of JIS S 6061:2020 in an environment of 25°C and 65% relative humidity, and a sensory evaluation was performed. The evaluation criteria are as follows. A: Very good writing feel B: Good writing feel C: Slightly poor writing feel D: Poor writing

[0123] (Follow-up test) Three test ballpoint pens having the first ballpoint pen tip (φ0.5 mm) and the second ballpoint pen tip (φ0.3 mm) were prepared for each example and comparative example. After removing the packing, the pens were written at a temperature of 25 ° C. and a relative humidity of 65% at a writing angle of 70 °, a writing load of 1.00 N, a writing speed of 7 cm / sec (normal speed writing), and a writing speed of 10 cm / sec (speed writing). The 100 m of handwriting obtained by spiral writing using paper conforming to the specifications of test paper B of JIS S 6061:2020 was visually confirmed. The evaluation criteria are as follows. A: There is no smearing on either the first or second ballpoint pen tip. B: No smearing is observed with the first ballpoint pen tip, but some smearing is observed with the second ballpoint pen tip at a writing speed of 10 cm / sec (fast writing). C: No smearing is observed with either the first or second ballpoint pen tip at a writing speed of 7 cm / sec. D: Blurring is observed even at a writing speed of 7 cm / sec with both the first ballpoint pen tip and the second ballpoint pen tip.

[0124] (Bote confirmation test) Three test ballpoint pens having the above-mentioned first ballpoint pen tip were prepared for each Example and Comparative Example. After removing the packing, the temperature was 25 ° C., the relative humidity was 65%, and the writing angle was 70 °, the writing load was 1.00 N, the writing speed was 7 cm / sec (normal writing pressure), the writing load was 2.00 N, the writing speed was 7 cm / sec (strong writing pressure). The 100 m of handwriting obtained by spiral writing using paper conforming to the specifications of test paper B of JIS S 6061:2020 was visually confirmed. The evaluation criteria are as follows. A: There is absolutely no bulk. B: Blurring is observed under strong writing pressure conditions, but not under normal writing pressure. C: Bote is visible. D: There are many bulges. Blots are a phenomenon in which, when writing with a ballpoint pen, ink that does not transfer completely to the surface being written on adheres to the outer surface of the ballpoint holder, accumulates, and grows into large clumps of ink that then adhere to the surface being written on.

[0125] (Non-contact ink leakage test 1 (leakage test 1)) Three test ballpoint pens with the first ballpoint pen tip were prepared for each Example and Comparative Example, and after handwriting "Diet Date" (the character string shown in Figure 7) in an environment of 25°C temperature and 65% relative humidity, the pens were left face down for three days. The size of the ink leaking from the pen tip was then confirmed at 50x magnification using a digital microscope (Keyence Corporation, VHX-7000), and the outermost diameter of the ink leaking from the tip opening 19 was measured and the average value was calculated. The evaluation criteria are as follows. A: No leakage to 0.30mm or less B: More than 0.30mm and less than 0.50mm C: More than 0.50mm and less than 1.00mm D: More than 1.00mm

[0126] (Non-contact ink leakage test 2 (leakage test 2)) Three test ballpoint pens with the above-mentioned first ballpoint pen tip were prepared for each Example and Comparative Example, and after handwriting "Diet Date" (the character string shown in Figure 7) in an environment of 25°C temperature and 30% relative humidity, the pens were left face down for three days. The size of the ink leaking from the pen tip was then confirmed at 50x magnification using a digital microscope (Keyence Corporation, VHX-7000), and the outermost diameter of the ink leaking from the tip opening 19 was measured and the average value was calculated. The evaluation criteria are as follows. A: No leakage to 0.30mm or less B: More than 0.30mm and less than 0.50mm C: More than 0.50mm and less than 1.00mm D: More than 1.00mm

[0127] (Pen tip contact ink leakage confirmation test 3 (leak confirmation test 3)) Three test ballpoint pens each having the above-mentioned first ballpoint pen tip and a 50 g weight attached were prepared for each Example and Comparative Example, and the "Date of the Diet" (the character string shown in Figure 7) was written by hand in an environment of 25°C temperature and 30% relative humidity. After that, the pen tip was placed vertically against an acrylic resin plate and left to stand for three days, and the size of the ink that had leaked from the pen tip onto the acrylic resin plate was confirmed at 20x magnification using a digital microscope, the diameter was recorded, and the average value was calculated. A: No leakage to 0.30mm or less B: More than 0.30mm and less than 0.50mm C: More than 0.50mm and less than 1.00mm D: More than 1.00mm

[0128] [Table 1]

[0129] [Table 2]

[0130] [Table 3]

[0131] [Table 4]

[0132] [Table 5]

[0133] [Table 6]

[0134] [Table 7]

[0135] [Table 8]

[0136] [Table 9]

[0137] [Table 10]

[0138] The ink compositions of Examples 1 to 32 contain a first phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group with a carbon number of 4 or more and 17 or less, a second phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group with a carbon number of 18 or more and 24 or less, water, and a nonionic surfactant.

[0139] Therefore, when writing with a ballpoint pen, a thick, cushiony multilayer film containing a layer of phosphate ester and a layer of nonionic surfactant is formed between the ball at the nib and the metal surface of the receiving seat, and this multilayer film can be maintained between the ball and the receiving seat even when writing at high speed (following test) or with high writing pressure (blot confirmation test), resulting in good lubrication during writing, a good writing feel, and suppression of smearing, skipped lines, or blotting. Furthermore, since the nonionic surfactant does not wet and spread on areas where there is no metal, excessive wetting and spreading of the phosphate ester, which interacts with the nonionic surfactant, is suppressed, which is thought to have effectively suppressed leakage of the ink composition from the nib (nib ink leakage confirmation tests 1 to 3).

[0140] Therefore, it is believed that the ink compositions and ballpoint pens of Examples 1 to 32 were able to effectively suppress ink leakage while producing good handwriting with a good writing feel even when writing at high speed or with high writing pressure.

[0141] Furthermore, in the ballpoint pens of Examples 1 to 32, the amount of oil-based ink composition discharged per 100 m of writing distance under specific conditions was 0.04 g or more and 0.30 g or less, and although the amount of ink composition discharged was relatively large for an oil-based ballpoint pen, there was little bleed-through (bleed-through confirmation test). This is thought to be because the multilayer film formed between the ball and the metal surface of the receiving seat was discharged from the pen tip and transferred onto the paper surface during writing, and the multilayer film on the paper surface inhibited the penetration of the ink into the paper.

[0142] Therefore, the ballpoint pens of Examples 1 to 32 can effectively suppress ink leakage, while providing a good writing feel and producing good handwriting even when writing at high speed or with high writing pressure, and can suppress bleed-through.

[0143] The ink compositions of Comparative Examples 1 and 3 to 6 do not contain either or both of the first phosphate ester and the second phosphate ester, and therefore it is difficult to form a multilayer film having a thick and dense structure between the ball of the pen tip and the metal surface of the receiving seat. This is thought to be why good writing feel and handwriting were not obtained when writing at high speed (following test) or when writing with high writing pressure (blob check test).

[0144] Furthermore, the ink compositions of Comparative Examples 1 and 6 did not contain a nonionic surfactant, which is thought to have resulted in the ink composition not being able to spread onto areas without metal, causing leakage of the ink composition from the pen tip (Pen Tip Ink Leakage Confirmation Tests 1 to 3).

[0145] Furthermore, the ink compositions of Comparative Examples 2 and 5 do not contain water. Therefore, a layer of nonionic surfactant incorporating water is not formed, and the cushioning properties of the multilayer film are poor. Therefore, when writing with a ballpoint pen, a multilayer film is difficult to form or maintain between the ball at the pen tip and the metal surface of the receiving seat. Therefore, it is thought that when writing at high speed (following ability test) or when writing with high writing pressure (blot confirmation test), a good writing feel and handwriting cannot be obtained, or leakage of the ink composition from the pen tip occurs (pen tip ink leakage confirmation tests 1 to 3).

[0146] In Comparative Examples 1, 2, 5, and 6, the ink compositions did not contain a first phosphate ester, a second phosphate ester, a nonionic surfactant, or water. This is thought to have made it difficult for a multilayer film to form between the ball at the pen tip and the metal surface of the holder, or to have the multilayer film maintained, making it difficult for the multilayer film to transfer to the paper surface during writing. This is thought to have resulted in little suppression of ink penetration into the paper (bleed-through confirmation test).

[0147] In Comparative Example 7, the ink composition contained a first phosphate ester, a second phosphate ester, a nonionic surfactant, and water, but the ink ejection volume was very large. For this reason, it is thought that the multilayer film formed between the ball of the pen tip and the metal surface of the receiving seat was unable to significantly suppress the penetration of ink into the paper, even if it was transferred to the paper surface during writing (bleed-through confirmation test).

[0148] In the ink compositions of Examples 1 to 32, the difference between the number of carbon atoms in the hydrocarbon group of the second phosphate ester and the number of carbon atoms in the hydrocarbon group of the first phosphate ester is 4 or more. Therefore, when writing with a ballpoint pen, a thick multilayer film containing a layer of phosphate ester and a layer of nonionic surfactant is more likely to be formed between the ball at the pen tip and the metal surface of the receiving seat, which is thought to be why good handwriting with a good writing feel could be obtained even when writing at high speed (following ability test) or when writing with high writing pressure (smudge confirmation test).

[0149] Furthermore, in the ink compositions of Examples 1 to 32, the hydrocarbon group of the first phosphate ester has a carbon number of 12 or more and 14 or less, and the hydrocarbon group of the second phosphate ester has a carbon number of 18 or more and 20 or less. Therefore, when writing with a ballpoint pen, a thick multilayer film containing a phosphate ester layer and a nonionic surfactant layer is more likely to be formed between the ball at the pen tip and the metal surface of the receiving seat, which is thought to be why good handwriting with a good writing feel can be obtained even when writing at high speed (following ability test) or when writing with high writing pressure (blob confirmation test).

[0150] Furthermore, in the ink compositions of Examples 1 to 11 and 13 to 31, the HLB value of the first phosphate ester and the HLB value of the second phosphate ester are from 4 to 14. Therefore, water is more easily retained in the nonionic surfactant layer, and the cushioning properties of the multilayer film formed between the metal surfaces of the ball and the receiving seat are enhanced. This is thought to be why good handwriting with a good writing feel could be obtained even when writing at high speed (following ability test) or when writing with high writing pressure (smudge confirmation test).

[0151] Furthermore, in the ink compositions of Examples 1 to 11, 13 to 28, and 32, the HLB value of the first phosphate ester and the HLB value of the second phosphate ester are from 7 to 12. Therefore, water is more easily retained in the nonionic surfactant layer, and the cushioning properties of the multilayer film formed between the ball and the metal surface of the receiving seat are enhanced, which is thought to be why good handwriting with a good writing feel was obtained even when writing at high speed (following ability test) or when writing with high writing pressure (smudge confirmation test).

[0152] Furthermore, the ink compositions of Examples 1 to 32 have a total content of the first phosphate ester and the second phosphate ester of 0.4% by weight or more and 3.0% by weight or less. Therefore, the density of the phosphate ester layer formed on the metal surface of the ball and the receiving seat is appropriate, and a multilayer film of appropriate density is formed between the ball at the pen tip and the metal surface of the receiving seat. This is thought to have effectively suppressed ink leakage (pen tip ink leakage confirmation tests 1 to 3), while also providing a good writing feel and handwriting even when writing at high speed (following ability test) or with high writing pressure (blob confirmation test).

[0153] Furthermore, in the ink compositions of Examples 1 to 32, the weight ratio of the content of the first phosphate ester to the content of the second phosphate ester is from 0.2 to 8.0. Therefore, the phosphate ester layer formed on the metal surface of the ball and the receiving seat is likely to have a dense structure, and a multilayer film of appropriate density is formed between the ball at the pen tip and the metal surface of the receiving seat. This is thought to have effectively suppressed ink leakage (pen tip ink leakage confirmation tests 1 to 3), while also providing a good writing feel and handwriting even when writing at high speed (following ability test) or with high writing pressure (blob confirmation test).

[0154] Furthermore, in the ink compositions of Examples 1 to 28, 31, and 32, the weight ratio of the content of the first phosphate ester to the content of the second phosphate ester is 0.25 or more and 4.0 or less. Therefore, the phosphate ester layer formed on the metal surface of the ball and the receiving seat is likely to have a denser structure, and a multilayer film of appropriate density is formed between the ball at the pen tip and the metal surface of the receiving seat. This is thought to have effectively suppressed ink leakage (pen tip ink leakage confirmation tests 1 to 3), while also providing a good writing feel and handwriting even when writing at high speed (following ability test) or when writing with high writing pressure (blob confirmation test).

[0155] Furthermore, the ink compositions of Examples 1 to 15, 17 to 24, and 26 to 32 each contain a nonionic surfactant with an HLB value of 4 or more and 15 or less. These ink compositions are hydrophilic to a certain extent, which facilitates water absorption into the nonionic surfactant layer through interaction with water. Furthermore, the ink compositions are not excessively hydrophilic, which facilitates interaction with the hydrocarbon groups of the first and second phosphate esters, which is believed to facilitate the formation of the multilayer film described above between the ball and the metal surface of the receiving seat. Therefore, it is believed that ink leakage can be effectively suppressed (pen tip ink leakage confirmation tests 1 to 3), and a good writing feel and handwriting were obtained even when writing at high speed (following test) or with high writing pressure (blot confirmation test).

[0156] The contents described in each of the above embodiments can be understood, for example, as follows.

[0157] [1] At least one embodiment of the present invention relates to a ballpoint pen refill (200) for an oil-based ballpoint pen, an ink reservoir (12); an oil-based ink composition (15) filled in the ink reservoir; a ballpoint pen tip (10) attached to the front end of the ink reservoir tube so that the oil-based ink composition is supplied; Equipped with The oil-based ink composition comprises a first phosphate ester that is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group having 4 to 17 carbon atoms; a second phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group having 18 to 24 carbon atoms; Water and a nonionic surfactant; Contains When written on paper conforming to the specifications of test paper B defined in JIS S 6061:2020 under the writing conditions of a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec, the amount of the oil-based ink composition discharged per 100 m of writing distance is 0.04 g or more and 0.30 g or less.

[0158] According to the configuration [1] above, when writing with a ballpoint pen, a thick multilayer film (hereinafter referred to as the multilayer film) containing a layer of phosphate ester and a layer of nonionic surfactant is likely to be formed between the ball at the tip of the pen and the metal surface of the receiving seat. That is, the oil-based ink composition constituting the ballpoint pen refill of [1] above contains a first phosphate ester having a relatively small number of carbon atoms in the hydrocarbon group and a second phosphate ester having a relatively large number of carbon atoms in the hydrocarbon group, and the phosphate groups of these phosphate esters are adsorbed to the metal surfaces of the ball and the receiving seat, thereby forming a phosphate ester layer on the metal surfaces of the ball and the receiving seat. Here, because the second phosphate ester has a relatively long hydrocarbon group, a relatively thick phosphate ester layer is formed on the metal surface, and because the first phosphate ester has a relatively short hydrocarbon group, the second phosphate ester penetrates between the first phosphate esters, and a phosphate ester layer with a dense structure is quickly formed on the metal surface. The oil-based ink composition described above contains water and a nonionic surfactant. Therefore, when writing with a ballpoint pen, the hydrophobic group of the nonionic surfactant interacts with the hydrocarbon group of the phosphate ester, and a layer of the nonionic surfactant is formed between the layers of phosphate ester formed on the surfaces of the ball and the receiving seat, respectively, making it easy to obtain a thick multilayer film. Furthermore, the hydrophilic group of the nonionic surfactant interacts with water, and water with high surface tension is taken up by the nonionic surfactant layer, thereby improving the cushioning properties of the multilayer film. Thus, according to the configuration [1] above, when writing with a ballpoint pen, a multilayer film with a large thickness and high cushioning properties is easily formed between the ball and the metal surface of the receiving seat, so that the multilayer film can be maintained between the ball and the receiving seat even when writing at high speed or with high writing pressure, resulting in good lubrication during writing. This results in a good writing feel even when writing at high speed or with high writing pressure, and can prevent smearing, skipped lines, or blobbing. Furthermore, in the above-mentioned configuration [1], the nonionic surfactant does not tend to wet and spread on areas where there is no metal, so excessive wetting and spreading of the phosphate ester that interacts with the nonionic surfactant is suppressed, thereby effectively suppressing leakage of the ink composition from the pen tip. Therefore, according to the configuration [1] above, ink leakage can be effectively suppressed, and good handwriting can be obtained with a good writing feel even when writing at high speed or with high writing pressure.

[0159] On the other hand, in general, the greater the ink discharge volume of an oil-based ballpoint pen, the better the writing feel, but the greater the tendency for the ink to bleed through on the target paper. In this regard, in the configuration [1] above, the amount of ink discharged per 100 m of writing distance under specific conditions is 0.04 g or more and 0.30 g or less. This is a relatively large amount of ink composition discharged for an oil-based ballpoint pen, but the multilayer film formed between the ball and the metal surface of the receiving seat is discharged from the pen tip and transferred to the paper surface during writing, and the multilayer film on the paper surface inhibits the ink from penetrating into the paper. Therefore, it is possible to achieve both a good writing feel and inhibition of bleed-through.

[0160] As described above, the configuration [1] above can effectively suppress ink leakage, while providing a good writing feel and producing good handwriting even when writing at high speed or with high writing pressure, and can suppress bleed-through.

[0161] [2] In some embodiments, in the configuration of [1] above, The L between the written part and the non-written part on the back side of the paper on which handwriting has been formed by writing under the writing conditions. * a * b * Color difference ΔE in color space * ab is less than or equal to 20.0.

[0162] According to the above-mentioned configuration [2], although the amount of ink composition discharged is relatively large for an oil-based ballpoint pen, the L between the written portion and the non-written portion on the back surface of the paper on which the handwriting is formed is small. * a* b * Color difference ΔE in color space * ab is 20.0 or less, and bleed-through is suppressed. Therefore, it becomes easier to achieve both a good writing feel and suppression of bleed-through.

[0163] [3] In some embodiments, in the configuration of [1] or [2] above, The ballpoint pen tip is Ball (13) and a ball holder (14) for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, The ratio C / A of the forward / backward movement amount C of the ball to the diameter A of the ball is 5% or more and 10% or less.

[0164] According to the configuration [3] above, the ratio C / A of the ball's forward / backward movement C to the ball's diameter A is between 5% and 10%. Because the ball's forward / backward movement C is relatively large, the ink ejection volume of the oil-based ballpoint pen is large, but the multilayer film on the paper surface prevents the ink from penetrating into the paper during writing. This allows for both a good writing feel and prevention of bleed-through.

[0165] [4] In some embodiments, in any of the configurations [1] to [3] above, The ballpoint pen tip is The ball and a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, The crimping angle of the tip of the ball holder is between 70 degrees and 90 degrees.

[0166] According to the configuration [4] above, the crimping angle of the tip of the ball holder is between 70 and 90 degrees, and because the crimping angle is relatively large, the ink discharge volume of the oil-based ballpoint pen is large, but the multilayer film on the paper surface prevents the ink from penetrating into the paper during writing. This allows for both a good writing feel and prevention of bleed-through.

[0167] [5] In some embodiments, in any of the configurations [1] to [4] above, The ballpoint pen tip is With a ball, a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, The ball holder includes a ball holding portion (21) that holds the ball, The ratio E / A of the maximum inner diameter E of the ball holding portion to the diameter A of the ball is 100% or more and 130% or less.

[0168] According to the configuration [5] above, the ratio E / A of the maximum inner diameter E of the ball-holding portion to the diameter A of the ball is 100% or more and 130% or less. Because the maximum inner diameter E of the ball-holding portion is relatively large, the ink ejection volume of the oil-based ballpoint pen is large, but the multilayer film on the paper surface prevents the ink from penetrating into the paper during writing. This allows for both a good writing feel and prevention of bleed-through.

[0169] [6] In some embodiments, in any of the configurations [1] to [5] above, The ballpoint pen tip is With a ball, a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, The ball holder includes a ball receiving seat (25) on which the ball can be seated, The ratio H / A of the diameter H of the ball receiving seat to the diameter A of the ball is 70% or more and 95% or less.

[0170] In oil-based ballpoint pens, increasing the ink discharge rate tends to cause blotting. In this regard, in the configuration [6] above, the ratio H / A of the diameter H of the ball seat to the diameter A of the ball is between 70% and 95%, and the diameter H of the ball seat is relatively large, so blotting is easily suppressed even when the ink discharge rate is large. Therefore, it is possible to achieve both a good writing feel and suppression of bleed-through, while also suppressing blotting.

[0171] [7] At least one embodiment of the oil-based ballpoint pen (ballpoint pen 100) of the present invention is A ballpoint pen refill (200) according to any one of the above [1] to [6]; A barrel (1) in which the ballpoint pen refill is housed; Equipped with.

[0172] According to the configuration [7] above, when writing with a ballpoint pen, a thick multilayer film (hereinafter referred to as the multilayer film) containing a layer of phosphate ester and a layer of nonionic surfactant is likely to be formed between the ball at the tip of the pen and the metal surface of the receiving seat. That is, the oil-based ink composition constituting the ballpoint pen of [7] above contains a first phosphate ester having a relatively small number of carbon atoms in the hydrocarbon group and a second phosphate ester having a relatively large number of carbon atoms in the hydrocarbon group, and the phosphate groups of these phosphate esters are adsorbed to the metal surfaces of the ball and the receiving seat, forming a phosphate ester layer on the metal surfaces of the ball and the receiving seat. Here, because the second phosphate ester has a relatively long hydrocarbon group, a relatively thick phosphate ester layer is formed on the metal surface, and because the first phosphate ester has a relatively short hydrocarbon group, the second phosphate ester penetrates between the first phosphate esters, and a densely structured phosphate ester layer is quickly formed on the metal surface. The oil-based ink composition described above contains water and a nonionic surfactant. Therefore, when writing with a ballpoint pen, the hydrophobic group of the nonionic surfactant interacts with the hydrocarbon group of the phosphate ester, and a layer of the nonionic surfactant is formed between the layers of phosphate ester formed on the surfaces of the ball and the receiving seat, respectively, making it easy to obtain a thick multilayer film. Furthermore, the hydrophilic group of the nonionic surfactant interacts with water, and water with high surface tension is taken up by the nonionic surfactant layer, thereby improving the cushioning properties of the multilayer film. Thus, according to the configuration [7] above, when writing with a ballpoint pen, a multilayer film with a large thickness and high cushioning properties is easily formed between the ball and the metal surface of the receiving seat, so that the multilayer film can be maintained between the ball and the receiving seat even when writing at high speed or with high writing pressure, resulting in good lubrication during writing. This results in a good writing feel even when writing at high speed or with high writing pressure, and can prevent smearing, skipped lines, or blobbing. Furthermore, in the above-mentioned configuration [7], the nonionic surfactant does not tend to wet and spread on areas where there is no metal, so excessive wetting and spreading of the phosphate ester that interacts with the nonionic surfactant is suppressed, thereby effectively suppressing leakage of the ink composition from the pen tip. Therefore, according to the configuration [7] above, ink leakage can be effectively suppressed, and good handwriting can be obtained with a good writing feel even when writing at high speed or with high writing pressure.

[0173] On the other hand, generally, the greater the ink discharge volume of an oil-based ballpoint pen, the better the writing feel, but the greater the tendency for the ink to bleed through on the target paper. In this regard, in the configuration [7] above, the amount of ink discharged per 100 m of writing distance under specific conditions is 0.04 g or more and 0.30 g or less. While this is a relatively large amount of ink composition for an oil-based ballpoint pen, the multilayer film formed between the ball and the metal surface of the receiving seat is discharged from the pen tip and transferred to the paper surface during writing, and the multilayer film on the paper surface inhibits the ink from penetrating into the paper. Therefore, it is possible to achieve both a good writing feel and inhibition of bleed-through.

[0174] As described above, the configuration [7] above can effectively suppress ink leakage, while providing a good writing feel and producing good handwriting even when writing at high speed or with high writing pressure, and can suppress bleed-through.

[0175] The above describes an embodiment of the present invention, but the present invention is not limited to the above-described embodiment, and also includes forms in which the above-described embodiment is modified, or forms in which these forms are appropriately combined.

[0176] In this specification, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components. [Explanation of symbols]

[0177] 1 shaft cylinder 2 front axle 3 rear axle 4 Grip section 5 crown 6 clips 7 Rotor 8 Knock 9. Elastic members 10 Ballpoint Pen Tips 11 Chip holder 12 Ink reservoir 13 Ball 14 Ball Holder 15 Ink composition 16 Ink backflow prevention body 17 Float 18 coil springs 19 Tip opening 20. Inner protrusion 21 Ball holding part 22 Center hole 23 Posterior foramen 24 Ink groove 25 Ball receiving seat 100 ballpoint pens 200 refills 300 exterior body A. Diameter of ball 13 B. Inside diameter of tip opening 19 C. Distance traveled by ball 13 in the forward and backward directions D Ball protrusion length E Inner diameter of ball holding portion 21 F Width of ink groove 24 G Depth of ink groove 24 H Ball seat diameter I Center hole diameter α Seat angle of ball holding part 21 β Crimping angle γ Chamfer angle δ Taper angle

Claims

1. An ink reservoir tube; an oil-based ink composition filled in the ink reservoir; a ballpoint pen tip attached to the front end of the ink reservoir tube so as to supply the oil-based ink composition; Equipped with The oil-based ink composition comprises a first phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group having from 4 to 17 carbon atoms; a second phosphate ester which is a polyoxyethylene hydrocarbon phosphate ester having a hydrocarbon group having from 18 to 24 carbon atoms; Water and a nonionic surfactant; Contains When written on paper conforming to the specifications of test paper B specified in JIS S 6061:2020 under the writing conditions of a writing load of 1.00 N, a writing angle of 70 degrees, and a writing speed of 7 cm / sec, the amount of the oil-based ink composition ejected per 100 m of writing distance is 0.04 g or more and 0.30 g or less. Ballpoint pen refill.

2. The ballpoint pen tip is With a ball, a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, The ratio C / A of the forward / backward movement amount C of the ball to the diameter A of the ball is 5% or more and 10% or less. The ballpoint pen refill according to claim 1.

3. The ballpoint pen tip is With a ball, a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, The crimping angle of the tip of the ball holder is 70 degrees or more and 90 degrees or less. The ballpoint pen refill according to claim 1 or 2.

4. The ballpoint pen tip is With a ball, a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, the ball holder includes a ball holding portion that holds the ball, The ratio E / A of the maximum inner diameter E of the ball holding portion to the diameter A of the ball is 100% or more and 130% or less. The ballpoint pen refill according to claim 1 or 2.

5. The ballpoint pen tip is With a ball, a ball holder for holding the ball so that the ball is located at the front end of the ballpoint pen tip and can rotate; Including, the ball holder includes a ball receiving seat on which the ball can be seated; The ratio H / A of the diameter H of the ball receiving seat to the diameter A of the ball is 70% or more and 95% or less. The ballpoint pen refill according to claim 1 or 2.

6. A ballpoint pen refill according to claim 1 or 2, a barrel in which the ballpoint pen refill is housed; An oil-based ballpoint pen.

Images