Valve opening / closing type writing utensil

Abstract

Provided is a valve opening / closing type writing instrument capable of obtaining a soft writing feeling such as that with a brush and supplying ink stored in a barrel to a pen core by reliably opening a valve by an operation of pushing the pen core.　In this valve opening / closing type writing instrument, following an operation of pressing a pen tip of a pen core, a valve mechanism 5 is opened by the backward movement of the pen core 4 and a liquid in a liquid storage chamber 1a is supplied to the pen core. The valve opening / closing type writing instrument is characterized in that: when a writing drawing line width when a load (Ly) required to open the valve mechanism is applied to the pen core is Y [mm], a writing drawing line width when a load (Lx) at the start of writing is applied to the pen core is X [mm], and a writing drawing line width when an intermediate load (Lz = 0.5Ly) of 1 / 2 the load required to open the valve mechanism is applied to the pen core is Z [mm], Y / X >3 and Z / X > 2 are satisfied.

Description

Valve-opening / closing type writing instrument

[0001] This invention relates to a valve-opening / closing type writing instrument that can provide a soft writing feeling like that of a brush pen, and by an operation of pushing in the pen core, the valve mechanism opens, and a liquid such as ink stored in the shaft cylinder can be supplied to the pen core.

[0002] There is provided a valve-opening / closing type writing instrument that supplies a liquid such as ink stored in a shaft cylinder to an application body such as a pen core through a valve mechanism. Regarding this valve-opening / closing type writing instrument, many improvement proposals have been made. As an example, a valve-opening / closing type writing instrument disclosed in Patent Document 1 according to the proposal of the present applicant is known. According to the valve-opening / closing type writing instrument described in this Patent Document 1, a knock portion is arranged at the rear end portion of the shaft cylinder, and by performing a knock operation on this knock portion, the valve mechanism is opened, and a configuration for supplying a liquid such as ink to the pen core is adopted. According to this valve-opening / closing type writing instrument, it is necessary to change the holding of the writing instrument for the knock operation during writing.

[0003] Therefore, in order to solve the above-mentioned problems, the present applicant has proposed a valve-opening / closing type writing instrument disclosed in Patent Document 2. In the valve-opening / closing type writing instrument described in this Patent Document 2, by a pumping operation of pressing the pen tip against a writing surface or the like, the pen core is pushed into the shaft, the valve in the shaft is opened, and a liquid such as ink stored in the shaft cylinder is supplied to the pen core.

[0004] According to the valve-opening / closing type writing instrument described in this Patent Document 2, by performing the above-mentioned pumping operation, a liquid such as ink is supplied to the pen core. Therefore, operations such as changing the holding of the writing instrument for the knock operation during writing, as in the valve-opening / closing type writing instrument described in Patent Document 1, become unnecessary. Therefore, the writing operation can be smoothly continued.

[0005] Japanese Unexamined Patent Application Publication No. 2000-153694, Japanese Unexamined Patent Application Publication No. 2021-007921

[0006] Incidentally, in a valve-operated writing instrument, as disclosed in Patent Document 2, in which the valve is opened by a pumping operation in which the pen tip is pressed against the writing surface, it is desirable that the pen tip of the feed used therein be a rigid body with a certain degree of hardness. That is, when using a writing instrument that provides a soft writing feel like a brush, the opening and closing of the valve by the aforementioned pumping operation will be unreliable, making it difficult to ensure the reliability of supplying ink to the feed. Therefore, in this type of valve-operated writing instrument currently available, the pen tip of the feed is made of a material with a certain degree of hardness in order to ensure the reliability of opening and closing the valve by pumping.

[0007] This invention was made in view of the above circumstances, and aims to provide a valve-operated writing instrument that can provide a soft writing feel similar to that of a brush, and can reliably open the valve by pushing in the pen tip, thereby supplying ink, which is the writing fluid contained in the barrel, to the pen tip.

[0008] The valve-operated writing instrument according to this invention, made to solve the aforementioned problems, is characterized in that a nib is arranged at the front end of the barrel, and a valve mechanism is arranged between the nib and a liquid storage chamber formed inside the barrel, and when the tip of the nib is pressed against the nib, the nib moves backward, opening the valve mechanism and supplying liquid from the liquid storage chamber to the nib, and when the writing line width when the load required to open the valve mechanism (Ly) is applied to the nib is Y [mm], the writing line width when the initial load (Lx) is applied to the nib is X [mm], and the writing line width when an intermediate load (Lz = 0.5Ly) which is half the load required to open the valve mechanism is applied to the nib is Z [mm], Y / X > 3 and Z / X > 2.

[0009] In this case, the pen tip is preferably made by bundling synthetic fibers together in a cylindrical shape, with both ends in the longitudinal direction formed into conical shapes, and one end in the longitudinal direction serving as the pen tip. In addition, a cap is provided that is detachably attached to the front end of the barrel, and the cap has a cap body that covers the pen tip and a decorative member that covers a part of the outside of the cap body, and it is desirable that the cap body and the decorative member are formed by two-color molding.

[0010] The valve-operated writing instrument according to this invention employs a relatively soft material for the pen tip and impregnates it with ink as the writing fluid, thereby creating flexibility in the pen tip and enabling a writing experience similar to that of a brush. Furthermore, by selecting an appropriate ratio for the relationship between Y [mm], the line width when the load required to open the valve mechanism (Ly) is applied to the pen tip, X [mm], the line width when the initial load (Lx) is applied to the pen tip, and Z [mm], the line width when an intermediate load (Lz = 0.5Ly), which is half the load required to open the valve mechanism, is applied to the pen tip, the pen tip is characterized by having appropriate rigidity in the axial direction so that it reliably contributes to the opening operation of the valve mechanism in response to the pressing load applied in the axial direction of the pen tip.

[0011] As a result, the valve-operated writing instrument according to this invention provides a writing feel similar to that of a brush, and also allows the valve mechanism to be opened by pushing in the pen tip, thereby reliably supplying ink, which is the writing fluid contained in the barrel, to the pen tip.

[0012] This diagram shows the overall configuration of the valve-operated writing instrument according to this invention, where (A) is a top view, (B) is a front view, and (C) is a central cross-sectional view along the axial direction. This diagram shows the configuration of the writing instrument body with the cap removed, where (A) is a front view and (B) is a central cross-sectional view along the axial direction. This is an exploded view of the parts that make up the entire valve-operated writing instrument. This diagram shows the individual configuration of the cap, where (A) is a top view, (B) is a front view, (C) is a central cross-sectional view along the axial direction, (D) is a perspective view with the front end facing forward, (E) is a left side view, (F) is a right side view, and (G) is a perspective view with the rear end facing forward. This diagram shows the cap body which is the primary molding side of the two-color molded cap, where (A) is a top view, (B) is a front view, (C) is a central cross-sectional view along the axial direction, (D) is a perspective view with the front end facing forward, (E) is a left side view, (F) is a right side view, and (G) is a perspective view with the rear end facing forward. The images show the decorative members that form the secondary molding side of the two-color molded cap, with (A) being a top view, (B) a front view, (C) a central cross-sectional view along the axial direction, (D) a perspective view with the front end facing forward, (E) a perspective view with the rear end facing forward, (F) a left side view, (G) a right side view, and (H) a perspective view from a different viewpoint than (E). The individual components of the pen tip are shown, with (A) a perspective view, (B) a front view, and (C) a side view viewed from the axial direction.

[0013] The valve-operated writing instrument according to this invention will be described based on the embodiment shown in the figures. In the following figures, the same parts are indicated by the same reference numerals. However, in the overall configuration diagrams shown in Figures 1 and 2, due to space limitations, representative parts are indicated by reference numerals, and details of each part will be explained by referring to the reference numerals shown in the exploded view of parts shown in Figure 3 or the individual component diagrams shown in Figures 4 to 7. In the following description of the valve-operated writing instrument, the side where the pen nib is located will be referred to as the "front end or front," and the opposite side will be referred to as the "rear end or rear."

[0014] As shown in Figures 1 to 3, this valve-operated writing instrument has a barrel 3 formed by attaching a front barrel 2, which tapers in diameter in a stepped manner toward the front, to the front end of a cylindrical rear barrel 1, which has a closed rear end. As shown in Figures 1 and 2, the inside of the rear barrel 1 forms a liquid storage chamber 1a for containing ink as writing fluid, and as shown in Figure 3, a slightly reduced diameter section 1b is formed at the front end of the rear barrel 1. A front end opening 1c is formed in the reduced diameter section 1b, and a male screw 1d is formed on the circumferential surface of the reduced diameter section 1b.

[0015] Furthermore, as shown in Figures 1 and 2, a female thread 2a is formed inside the rear end opening of the front shaft 2, and the female thread 2a of the front shaft 2 is screwed onto the male thread 1d of the rear shaft 1, thereby axially connecting the front shaft 2 to the rear shaft 1 and forming the shaft cylinder 3 as described above. In addition, as shown in Figure 3, an annular projection 2c is formed along the circumference of the small diameter front end portion 2b of the front shaft 2, and this annular projection 2c provides a clicking sensation when the cap 12, which will be described later, is attached to or detached from the front shaft 2.

[0016] A pen nib 4 is positioned to move axially within the front end of the barrel 3, i.e., within the front end opening 2d of the front barrel 2. Immediately behind the pen nib 4 is a valve mechanism 5, which includes a coil spring 7 that biases the pen nib 4 forward. As shown in the exploded view of the parts in Figure 3, the valve mechanism 5 consists of a valve cylinder 6, a coil spring 7, a valve stem 8, and a valve seat 9. The valve cylinder 6 forms the outer casing of the valve mechanism 5. An annular flange 6b is formed outward at its front end opening 6a, and the diameter is slightly reduced at the rear end, with a plurality (four) of side wall openings 6c formed at equal intervals along the circumferential side wall. These side wall openings 6c are provided to introduce ink from the liquid storage chamber 1a of the rear barrel 1 into the valve cylinder 6.

[0017] Furthermore, a valve body 8a having a tapered surface that decreases in diameter toward the front is formed in the longitudinal center of the valve stem 8, and a rod-shaped portion 8b is formed behind this valve body 8a, with the aforementioned coil spring 7 mounted so as to surround this rod-shaped portion 8b. The valve stem 8 and coil spring 7 are housed in the valve cylinder 6, and the rear end of the coil spring 7 abuts against the inner wall at the rear end of the valve cylinder 6. The front end of the valve stem 8 forms a cylindrical body 8d having a front end opening 8c.

[0018] A valve seat 9, formed in an annular shape, is fitted into the front end opening 6a of the valve cylinder 6. The front end of the coil spring 7 abuts against the back surface of the valve body 8a formed on the valve stem 8, and under the biasing force of the coil spring 7, the cylindrical body 8d located on the front end side of the valve stem 8 is positioned to protrude forward from the opening 9a of the valve seat 9. As a result, the valve body 8a, which has a tapered surface formed on the valve stem 8, abuts against the valve seat 9b, which is the rear end opening of the valve seat 9, and the valve mechanism 5 maintains a closed state.

[0019] The valve mechanism 5 is assembled by pushing the valve seat 9 against the valve cylinder 6 until the flange 6b of the valve cylinder 6 abuts against the flange 9c of the valve seat 9. The flange 6b of the valve cylinder 6 and the flange 9c of the valve seat 9 are then sandwiched between the opening edge of the front end opening 1c of the rear shaft 1 and the annular stepped portion formed inside the front shaft 2, thereby positioning and arranging the valve mechanism 5 inside the front end opening 1c of the rear shaft 1 (see Figures 1 and 2). A liquid storage body 11, which is cylindrical and has a shaft hole 11a, is also arranged inside the front shaft 2. This liquid storage body 11 is made of, for example, a sponge such as urethane or felt, and is positioned in contact with the front end of the valve mechanism 5.

[0020] The liquid storage body 11 temporarily stores the writing fluid (ink) supplied from the liquid storage chamber 1a via the valve mechanism 5 when the valve mechanism 5 is opened by a pumping operation (see Figure 2), and acts to smoothly supply the writing fluid to the pen nib 4. The rear end of the pen nib 4, which is positioned in the front end opening 2d of the front barrel 2, passes through the shaft hole 11a of the liquid storage body 11 and is inserted into the front end opening 8c of the valve stem 8. As a result, the pen nib 4 is kept in a forward position by the biasing force of the coil spring 7 located in the valve mechanism 5, and the valve mechanism 5 is kept in a closed state (see Figure 1).

[0021] Figure 4 shows the individual components of the cap 12. Figure 5 shows the cap body 12A, which is the primary molded side of the cap 12 that is two-color molded, and Figure 6 shows the decorative member 12B, which is the secondary molded side that is also two-color molded, separated from the cap body 12A that is the primary molded side. This cap 12 is detachably attached to the small diameter front end portion 2b of the front shaft 2 that constitutes the barrel 3 by fitting, and as shown in Figures 4 and 5, it comprises an inner cap 12a that protects the pen nib 4 by covering it, and a cylindrical outer cap 12b that surrounds the inner cap 12a and has a closed top surface.

[0022] In Figure 5, which shows the cap body 12A being initially molded, a plurality of small protrusions 12c are arranged at approximately equal intervals along the inner circumference of the opening of the inner cap 12a. These small protrusions 12c overcome the annular protrusions 2c formed on the front shaft 2 when the cap 12 is attached to or detached from the front end of the shaft 3, thereby creating a clicking sensation. Therefore, the aforementioned clicking sensation can be obtained both when attaching the cap 12 to the shaft 3 and when removing the cap 12 from the shaft 3.

[0023] Furthermore, multiple ribs 12d are formed inside the outer cap 12b, oriented in the axial direction. These ribs 12d are arranged at approximately equal intervals along the inner circumference of the outer cap 12b. These multiple ribs 12d function as guides for the pen tip when the cap 12 is attached to the front end of the barrel 3.

[0024] Furthermore, a crown placement recess 12e is formed on the closed top surface on the front side of the cap body 12A for forming the crown portion 12g during secondary molding. This crown placement recess 12e is formed from the center of the closed top surface toward the convex portion 12f formed along the longitudinal direction on the side surface of the cap body 12A. The aforementioned convex portion 12f formed along the longitudinal direction on the side surface of the cap body 12A serves as a base for forming the side decoration 12h, which will be described later, during secondary molding.

[0025] Figure 6 shows the configuration of the decorative member 12B on the secondary molding side, which is molded to cover a portion of the primary molding side cap body 12A. This decorative member 12B is generally molded in an L-shape and comprises a crown portion 12g positioned on the closed top surface side of the cap body 12A, and a side ornament 12h which is bent and molded at approximately a right angle to the crown portion 12g to cover the convex portion 12f of the cap body 12A.

[0026] In other words, the crown portion 12g is molded to substantially fill the crown placement recess 12e formed in the cap body 12A shown in Figure 5, and the side ornament 12h is molded to exceed the width of the convex portion 12f formed in the cap body 12A and cover the entire convex portion 12f. As a result, the width dimensions of the L-shaped crown portion 12g and the side ornament 12h are configured to be substantially the same.

[0027] Therefore, as shown in Figure 6(E) which depicts the decorative member 12B as a single component, a recessed portion 12h1 corresponding to the convex portion 12f of the cap body 12A is formed on the surface of the side ornament 12h facing the cap body 12A. As a result, the crown portion 12g constituting the decorative member 12B is embedded in the crown arrangement recess 12e on the cap body 12A side, and the side ornament 12h, which is bent at almost a right angle to the crown portion 12g, is molded with the aforementioned recessed portion 12h1 covering the convex portion 12f of the cap body 12A.

[0028] This makes it possible to obtain a cap 12 in which sufficient bonding strength is ensured between the decorative member 12B and the cap body 12A during two-color molding. Furthermore, by using different colorings for the resin materials used to mold the cap body 12A and the decorative member 12B, the function of the decorative member can be further enhanced. The side ornament 12h of the decorative member 12B is formed to protrude axially from the circumferential surface of the cap 12, thereby serving as an anti-rolling mechanism for the writing instrument.

[0029] Figure 7 shows the external structure of the pen tip 4. This pen tip 4 is constructed by bundling synthetic fibers together as fiber bundles to form a cylindrical shape, and shaping both ends in the longitudinal direction into conical shapes, so that either end in the longitudinal direction can be used as a pen tip. Therefore, its external appearance consists of a central cylindrical part 4a and conical parts 4b formed at both ends thereof. This pen tip 4 is preferably made by creating a base rod by bundling nylon fibers together as parallel fiber bundles with a binder to form a cylindrical shape, cutting this base rod to a predetermined length, and polishing both ends into the same conical shape.

[0030] In the pen nib 4 with the above-described configuration, during the process of creating the base rod by binding the fiber bundles together in a cylindrical shape with a binder, an outer layer of binder that makes it difficult for ink to pass through is formed on the circumferential surface of the base rod corresponding to the cylindrical portion 4a of the pen nib 4. Therefore, by polishing both ends of the pen nib 4 into a conical shape, the outer layer of binder is removed and the fibers are exposed, so that the ink flows easily in the axial direction of the pen nib 4, that is, along the longitudinal direction of the fibers. Moreover, since both ends of the pen nib 4 are formed into a conical shape, sufficient flexibility is generated in the ink-filled pen tip, allowing for a soft writing feel similar to that of a brush.

[0031] As described above, with the valve-operated writing instrument, as mentioned at the beginning, the feed 4 is pushed into the barrel 2 by a pumping operation that presses the pen tip against the writing surface, and the valve stem 8, which constitutes the valve mechanism 5, retracts against the biasing force of the coil spring 7. As a result, the valve body 8a formed on the valve stem 8 separates from the valve seat 9b of the valve seat body 9 and opens, and the ink in the liquid storage chamber 1a is supplied to the liquid absorbent 11 and the pen tip 4 through the opening 9a of the valve seat body 9 (see Figure 2). When the pushing of the pen tip 4 is released, the valve body 8a contacts the valve seat 9b of the valve seat body 9 due to the biasing force of the coil spring 7 and closes, stopping the flow of ink supplied from the liquid storage chamber 1a to the liquid absorbent 11 and the pen tip 4 (see Figure 1).

[0032] Next, we will describe ink compositions that can be suitably used in the valve-operated writing instrument according to the present invention described above.

[0033] A preferred writing ink to be contained in the liquid storage chamber 1a of the rear shaft 1 comprises a pigment, a surfactant having an acetylene bond, a β-propiolactone compound, and a solvent, wherein the surfactant having an acetylene bond has an HLB value of 6 to 15, and the β-propiolactone compound contains an alkyl ketene dimer made from a fatty acid having 14 to 20 carbon atoms.

[0034] The colorants can be arbitrarily selected from conventionally known pigments and dyes. Examples of pigments include inorganic pigments such as metal oxides or metal salts, organic pigments such as organic dye pigments or lake pigments, and glossy pigments such as aluminum pigments. Examples of dyes include acid dyes, basic dyes, direct dyes, reactive dyes, vat dyes, sulfide dyes, metal-containing dyes, cationic dyes, and disperse dyes. Among these, titanium dioxide is particularly preferred because it can be combined with complementary pigments, as described later, to achieve a wide range of colors.

[0035] The pigment is preferably surface-treated with a coating material. Preferred materials for the coating material include inorganic oxides such as silica, alumina, zirconia, and zinc oxide, metals such as molybdenum, or phosphates. This is because surface treatment of the pigment with the coating material suppresses aggregation of pigments in the ink, stabilizing the dispersion of the pigment, and also suppresses the reaction between the pigment and water, thereby reducing bubble formation. Furthermore, when a pigment containing metal is subjected to shear force from a mixer during ink manufacturing, the deformation and damage of the pigment, which suppresses the elution of metal ions, improves the long-term stability of the ink. Considering the dispersion stability in the ink, the coating material for the pigment is more preferably an inorganic oxide containing silica or alumina. Regarding the pigment, the amount of coating material applied to the surface-treated pigment is preferably 0.01% to 20% of the mass of the coating material relative to 100 parts by mass of the pigment after surface treatment. If the coating amount is within this range, ink dispersion and suppression of metal elution can be easily achieved.

[0036] When using pigments surface-treated with inorganic oxides, considering dispersion stability in ink, it is preferable that the pigment surface-treated with inorganic oxides has a positive or negative surface charge in the ink. In particular, when using pigments treated with inorganic oxides containing silica, it is preferable that the surface charge is negative, and when using pigments treated with inorganic oxides containing alumina, it is preferable that the surface charge is positive. Such pigments exhibit good dispersibility in the composition, but dispersibility and redispersibility can be further enhanced by combining them with pigment dispersants described later. When the surface-treated pigment has the above surface charge, considering dispersion stability in ink, it is preferable that the surface-treated pigment is titanium dioxide. The average particle size of the pigment is preferably 0.01 μm to 30 μm on a volume basis. If the average particle size of the pigment is within the above numerical range, even when writing on a writing surface with large gaps between fibers such as paper or cloth, the pigment is less likely to penetrate the gaps between the fibers, making it easier to obtain vivid color development. In addition, when ink containing a pigment with an average particle size within the above numerical range is used in writing instruments such as markers, the ink ejection performance can be improved. In this specification, the average particle size can be measured by the particle size (D50) at 50% volume accumulation of the particle size distribution, measured by laser diffraction using a laser diffraction particle size distribution analyzer (product name "MicrotracHRA9320-X100", Nikkiso Co., Ltd.), unless otherwise specified. The pigment content in the ink is preferably 1% to 40% by mass, based on the total mass of the ink. If the pigment content is within the above numerical range, a decrease in ink ejection performance can be prevented, and the clarity and opacity of the ink and the writing formed using it can be maintained.

[0037] Furthermore, it is preferable to include a pigment dispersant. By combining a pigment dispersant with a pigment, it is possible to suppress the aggregation of pigments and improve the stability of the ink. The pigment dispersant used in the embodiment is not particularly limited as long as it has the effect of improving the dispersibility of the pigment, but when using a pigment surface-treated with an inorganic oxide, it is preferable to use a pigment dispersant having anionic or cationic adsorbent groups, considering the dispersion stability of the pigment. When using a pigment surface-treated with an inorganic oxide containing silica in the composition of the embodiment, it is preferable that the pigment dispersant has cationic adsorbent groups. Considering the stability and safety of the ink composition, it is preferable that the acid-base balance is near neutral, but at this pH, the pigment in the ink composition has a negative surface charge, so cationic adsorbent groups are easily adsorbed to the pigment by electrical attraction, making dispersion easier. One or more types of pigment dispersants can be used. Furthermore, when using a pigment surface-treated with an inorganic oxide containing alumina in the composition, it is preferable that the pigment dispersant has anionic adsorbent groups. In the aforementioned acid-base conditions, the pigment has a positive surface charge, so anionic adsorption groups readily adsorb to the pigment by electrical attraction, making dispersion easy. In the embodiment, the content of the pigment dispersant is preferably 0.01% to 5% by mass, calculated on a solid content basis of the active ingredient. Furthermore, if A is the total content of the colorant relative to the total amount of the ink composition, and B is the total content of the pigment dispersant relative to the total amount of the ink composition, then B / A is preferably 0.005 ≤ B / A ≤ 0.5. When the content of the pigment dispersant and the ratio of the content of the pigment dispersant to the content of the colorant are within the above numerical range, the dispersibility of the pigment is good, and it is possible to suppress the viscosity of the ink composition from becoming excessively high.

[0038] The penetrating agent is preferably a surfactant having an HLB value of 4 to 18, considering its effect on improving wettability and its solubility in the ink composition. Here, the HLB value of the surfactant is a value proposed by Griffin to evaluate the hydrophilicity of a compound, and is calculated by the following formula. The HLB value obtained by the Griffin method is in the range of 0 to 20, and the larger the number, the more hydrophilic the compound is. HLB value = 20 × (mass %) of hydrophilic groups = 20 × (sum of formula weights of hydrophilic groups / molecular weight of surfactant) As the penetrating agent, it is preferable to select and use one or more from surfactants having an acetylene bond in their structure, fluorine-based surfactants, silicone-based surfactants, and succinic acid-based surfactants. By incorporating such surfactants into the ink, the surface tension can be lowered, improving the wettability of the ink to non-permeable recording media such as films, and improving writing performance by reducing smudging and gaps in writing on the non-permeable recording media. Among the aforementioned penetrating agents, surfactants having an acetylene bond are highly stable and can sustainably exhibit a wettability-improving effect, thereby improving writing performance by minimizing smudging and gaps in handwriting on the non-penetrating recording medium. Preferred penetrating agents are acetylene glycol-based surfactants, which are excellent at suppressing bubble generation and tend to suppress foaming of handwriting during writing, resulting in a smoother handwriting surface. Furthermore, the content of the surfactant having an acetylene bond is preferably between 0.001% by mass and 1.5% by mass. When the content is within the above numerical range, it is possible to achieve both suppression of foaming of handwriting and improvement of wettability.

[0039] The ink according to the embodiment preferably contains a β-propiolactone compound. The β-propiolactone compound in the embodiment is a compound having a β-propiolactone ring, and in the ink composition, it adsorbs with colorant particles, polyolefin particles (described later), and complementary pigments, forming bulky aggregates of colorant. When writing on a writing surface such as paper or cloth, which has large gaps between its fibers, the colorant does not penetrate into the writing surface through the gaps between the fibers, and the colorant adheres more easily to the fibers on the surface of the writing surface, resulting in good color development of the writing. Furthermore, when writing on a non-penetrating surface, it adsorbs to the writing surface, improving the fixation of the writing. In addition, since the β-propiolactone compound has an anti-slip effect, when writing on writing formed by the composition, even if lubricating substances such as hand grease are attached to the writing surface, the ink dispensing part of the writing surface is prevented from slipping. Thus, the β-propiolactone compound also has the effect of preventing interruptions in the writing during writing. In this embodiment, by using the penetrating agent and a β-propiolactone compound in combination, it is possible to create a writing instrument ink composition that not only improves the writing properties on the non-penetrating recording medium but also improves the fixation of the writing marks. At the same time, it also exhibits excellent color development and high fixation of writing marks even on writing materials with large gaps between fibers, such as paper and cloth, and allows for good writing on both non-penetrating and penetrating surfaces. In this embodiment, the β-propiolactone compound is not particularly limited as long as it exhibits the above effects, but it is preferably an alkyl ketene dimer composed of a fatty acid having 10 to 24 carbon atoms. When the number of carbon atoms of the fatty acid is within the above numerical range, the β-propiolactone compound is more likely to adsorb with the coloring agent and form bulky aggregates, and can be stably dispersed in the ink composition. Furthermore, considering stable dispersion, it is more preferable that it be an alkyl ketene dimer composed of a fatty acid having 14 to 20 carbon atoms. Furthermore, alkyl ketene dimers may be composed of multiple types of fatty acids with different numbers of carbon atoms, as long as the number of carbon atoms of the constituent fatty acids meets the above range.The β-propiolactone compound used in the embodiment is preferably an alkyl ketene dimer containing a C18 fatty acid as a constituent raw material, considering the formation and dispersibility of bulky aggregates. Furthermore, such an alkyl ketene dimer preferably has an average particle size of 0.1 μm to 2.0 μm. When the average particle size is within this range, the alkyl ketene dimer readily forms bulky aggregates with colorants and other materials, and readily exhibits good ink discharge properties. The above alkyl ketene dimer is preferably used as an emulsion, which allows for the maintenance of high stability over time. The content of the β-propiolactone compound is preferably 0.1% to 4% by mass relative to the total amount of the ink composition. When the content is within the above range, it is possible to prevent the ink viscosity from becoming too high and to prevent a decrease in ink discharge properties when writing. When the sum of the total content of the colorant relative to the total amount of the ink composition and the total content of the complementary pigment (described later) relative to the total amount of the ink composition is A, and the total content of the β-propiolactone compound relative to the total amount of the ink composition is B, it is preferable that the range is 0.005 ≤ B / A ≤ 0.5. This is because, within the above numerical range, the colorant adheres more easily to the surface of the writing surface, resulting in good color development, and the viscosity of the ink composition does not become too high, resulting in good ink discharge and excellent writing performance.

[0040] The ink according to the embodiment preferably contains a poorly water-soluble resin. A poorly water-soluble resin is a resin whose solubility in water (amount of solute per 100 g of water) is less than 1.0 g. In the ink composition, it binds to the bulky aggregates, colorants, and polyolefin particles described later, and adheres to the writing surface during writing, thereby improving the fixation and abrasion resistance of the writing and improving the color development of the writing. Therefore, in the writing ink of the embodiment, it is preferable to use both a β-propiolactone compound and a poorly water-soluble resin in combination, as this further improves the fixation and color development of the writing. In the embodiment, the poorly water-soluble resin is preferably used as an emulsion or dispersion, which allows the poorly water-soluble resin to maintain a stable dispersion state. Considering the improvement of the color development, fixation, and abrasion resistance of the writing, it is more preferable that the composition of the embodiment contains one or more selected from polyolefin resins, acrylic resins, nylon resins, and polyester resins. By including a polyolefin resin or acrylic resin, it is possible to achieve both good color development and high ink fixation and abrasion resistance. These effects are effectively manifested by using a β-propiolactone compound in combination with the above-mentioned poorly water-soluble resin. Considering the ink's color development and fixation, a copolymer of ethylene and acrylic acid is more preferable as the polyolefin resin used in the ink composition, and a self-emulsifying copolymer of ethylene and acrylic acid is particularly preferable. The acrylic resin used in the embodiments is a polymer containing acrylic acid or methacrylic acid in its repeating units, and it is possible to use one or more types of acrylic resins. To further improve ink fixation and abrasion resistance, acrylic styrene resin is preferred, and a self-crosslinking acrylic styrene copolymer is even more preferred. The molecular weight of the above-mentioned acrylic resin is not particularly limited, but generally, a mass-average molecular weight of 1,000 to 1,000,000 is used. Furthermore, the nylon resin and polyester resin used in the embodiments are not particularly limited as long as they have the effect of improving the color development, ink fixation, and abrasion resistance of the ink composition.The content of the poorly water-soluble resin is preferably 0.1% to 10% by mass relative to the total amount of the ink composition. Furthermore, if the total content of the β-propiolactone compound relative to the total amount of the ink composition is A, and the total content of the poorly water-soluble resin relative to the total amount of the ink composition is B, then it is preferable that the range is 0.1 ≤ B / A ≤ 5. This is because if the content of the poorly water-soluble resin and the ratio of the content of the poorly water-soluble resin to the content of the β-propiolactone compound are within the above numerical range, the adhesion of the colorant to the writing surface will be improved, and it will be easier to achieve excellent writing properties.

[0041] Suitable solvents include water and mixed solvents of water and organic solvents. Conventional waters such as deionized water, distilled water, and tap water can be used as the water. When using a mixed solvent of water and organic solvent, ethanol, n-propanol, isopropanol, etc., can be used as the organic solvent. Diols or triols with relatively high boiling points, such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and polyethylene glycol, can be used, but their concentration should be small. The organic solvent content is preferably 1% to 30% by mass relative to the total mass of the solvent. If the organic solvent content is within the above range relative to the total mass of the solvent, good drying performance and ink drying properties can be achieved.

[0042] The solvent content in the ink is preferably 20% to 90% by mass, based on the total mass of the composition. Within this numerical range, the solvent content allows for stable dissolution or dispersion of each component, and enables the formation of bulky aggregates in the ink that are easily redispersible.

[0043] Furthermore, the writing ink composition of the embodiment can be given high fixability and abrasion resistance to the handwriting by using polyolefin resin particles. Polyolefin resin particles are fine particles with surface lubricity, consisting of polyolefins such as polyethylene and polypropylene, and mixtures thereof, which suppress excessive force being applied to the handwriting when the handwriting is subjected to external forces such as abrasion, and are a different type of polyolefin resin from the poorly water-soluble resins mentioned above. The molecular weight of these polyolefins is not particularly limited, but for example, polyolefins with a mass-average molecular weight of 500 to 100,000 are preferred. If the mass-average molecular weight of the polyolefin resin particles is within the above numerical range, when this ink is used with a writing instrument such as a marker to write, it is possible to give the formed handwriting higher lubricity and consequently higher abrasion resistance, resulting in good handwriting. The polyolefin resin particles may contain materials other than polyolefins as needed. Therefore, using the aforementioned poorly water-soluble resin and polyolefin resin in combination is preferable because it is easier to improve the color development, fixation, and abrasion resistance of the handwriting, and in particular, it is easy to write well even when writing on an impermeable recording medium. The shape of the polyolefin resin particles is not particularly limited and can take any shape such as irregular, spherical, needle-shaped, plate-shaped, or square. The average particle diameter of the polyolefin resin particles is preferably 0.1 μm to 35 μm. If the average particle diameter of the polyolefin resin particles is within the above numerical range, when this ink is used with a writing instrument such as a marker to write, it is possible to impart higher lubricity and, consequently, higher abrasion resistance to the formed writing line, and good handwriting can be obtained. Furthermore, from the viewpoint of imparting high abrasion resistance, it is more preferable that it be 0.1 μm to 25 μm. The average particle diameter of the polyolefin resin particles can be measured by the Coulter counter method. The content of polyolefin resin particles in the ink is preferably 0.01% to 10% by mass, based on the total mass of the ink. If the content of polyolefin resin particles is within the above numerical range, ink ejection performance can be maintained, and higher lubricity can be imparted to the writing line.

[0044] The ink according to the embodiment may contain a complementary color pigment in order to adjust the color of the resulting writing line. In particular, when titanium oxide, which is white, is selected as the main pigment particles, various colors can be achieved by combining with a complementary color pigment. The complementary color pigment is not particularly limited, and pigments of various colors such as red, blue, yellow, green, white, and black can be used. Also, it is possible to use a pigment dispersion obtained by dispersing the pigment in a solvent. The content of the complementary color pigment in the ink is preferably 0.01% by mass to 15% by mass based on the total mass of the ink.

[0045] Further, the ink may contain, as necessary, extender materials, preservatives, defoamers, rust inhibitors, pH adjusters, bubble suppressants, bubble absorbers, shear-thinning property imparting agents, and viscosity adjusters.

[0046] The viscosity of the ink according to the embodiment is preferably low. The viscosity of the composition can be measured using an E-type rotational viscometer (manufactured by Brookfield). Specifically, the viscosity of the ink at 20°C is preferably 1 to 100 mPa·s when measured under the condition that the rotational speed is 100 rpm (shearing rate 380 sec−1). Also, when measured under the condition that the rotational speed is 10 rpm (shearing rate 38 / s), it is preferably 1 to 600 mPa·s. At a rotational speed of 1 rpm (shearing rate 3.8 / s), it is preferably 1 to 3000 mPa·s. If the viscosity of the ink is within the above numerical range, the ink ejection property can be improved, and the writing property on a non-permeable recording medium such as a film can also be improved.

[0047] The surface tension of the ink is preferably 10 to 35 mN / m at a 20°C environment. When the surface tension is within this range, it tends to prevent ink bleeding and show-through on the paper, improves the wettability of the ink, and reduces streaking and gaps in the writing on the non-permeable recording medium, thereby improving writing performance. In particular, surfactants having an acetylene bond in their structure are suitable for adjusting the surface tension of the ink. The surface tension is determined at a 20°C environment using a surface tension meter manufactured by Kyowa Interface Science Co., Ltd., with a platinum plate and measured by the vertical plate method. The pH of the ink is preferably 6 to 10. When the pH of the ink is within this range, it is possible to suppress discoloration of the ink composition and excessive viscosity. Furthermore, when using a pigment treated with an inorganic oxide containing silica or alumina in the ink composition, the dispersibility of the pigment can be further improved by using the aforementioned pigment dispersant. In the embodiment, the pH value can be measured at 20°C using, for example, an IM-40S pH meter (manufactured by Toa DKK Co., Ltd.). The ink according to the embodiment can be manufactured by any conventionally known method. Specifically, the required amounts of each component are blended and mixed using various stirrers such as propeller stirring, homodispersing, or homomixing machines, or various dispersers such as bead mills.

[0048] Next, the relationship between the load applied to the pen refill 4 and the width of the writing stroke at this time was verified for the examples and comparative examples of the pen refill 4 used in the valve-opening / closing type writing instrument according to this invention, and will be described below. The load (Ly) applied to the pen refill 4 required for the valve mechanism to open the valve was 5 N, the load (Lx) applied to the pen refill 4 as the starting load for writing was 0.2 N, and the intermediate load (Lz = 0.5Ly) which is half of the load required for the valve mechanism to open the valve was 2.5 N. The total length of the pen refill 4 in each example and comparative example was 30 mm, and the outer diameter dimension of the cylindrical portion 4a, that is, the outer diameter dimension of the pen refill 4 was φ4.5 mm. In a state where the above-mentioned loads Lx, Ly, and Lz were respectively applied in the axial direction of the pen refill 4, using a writing test machine compliant with JIS S6037, the widths X, Y, and Z of the writing strokes at a writing speed of 7 cm / s and a writing angle (holding angle of the pen tip) of 90° were measured respectively.

[0049] <Example 1> It was made of nylon and formed into the shape of FIG. 7. X = 0.8 mm, Y = 3.5 mm, Z = 2.4 mm Y / X = 4.38, Z / X = 3 <Comparative Example 1> It is a pen refill with a tip curved after adhering a polyethylene-made material. X = 1.3 mm, Y = 2.5 mm, Z = 2.2 mm Y / X = 1.92, Z / X = 1.69 <Comparative Example 2> It is a pen tip made by bundling polybutylene terephthalate with a wire diameter of 0.2 mm. X = 0.7 mm, Y = 7 mm, Z = 4.6 mm Y / X = 10, Z / X = 6.57 However, the valve could not be opened even when a load at the time of valve opening was applied.

[0050] In Example 1, when a force was applied in the axial direction, the valve operating load was transmitted. Different from Comparative Example 1, a thin writing stroke could be obtained at a low writing load, and a distinct writing stroke that could be drawn thick at a high writing load could be obtained. In Comparative Example 2, as described in the problems of the invention, the opening and closing of the valve due to pumping became unstable and it was unsuitable as a writing instrument equipped with a valve mechanism.

[0051] As is clear from the above description, the valve-operated writing instrument according to this invention provides a valve-operated writing instrument that can provide a soft writing feel similar to that of a brush, as described in the section on the effects of the invention above. In addition, it is possible to provide a valve-operated writing instrument that can reliably open the valve mechanism by a pumping operation that pushes in the pen tip, thereby supplying ink contained in the barrel to the pen tip.

[0052] 1 Rear shaft 1a Liquid storage chamber 2 Front shaft 3 Shaft cylinder 4 Pen tip 4a Cylindrical section 4b Conical section 5 Valve mechanism 6 Valve cylinder 7 Coil spring 8 Valve stem 8a Valve body 9 Valve seat body 9b Valve seat 11 Liquid storage element 12 Cap 12A Cap body 12B Decorative member 12a Inner cap 12b Outer cap 12e Crown placement recess 12f Convex section 12g Crown section 12h Side decoration 12h1 Recessed section

Claims

1. A valve-operated writing instrument in which a pen nib is positioned at the front end of the barrel, and a valve mechanism is positioned between the pen nib and a liquid storage chamber formed inside the barrel, and when the tip of the pen nib is pressed against the barrel, the pen nib moves backward, opening the valve mechanism and supplying liquid from the liquid storage chamber to the pen nib, wherein the line width when the load required to open the valve mechanism (Ly) is applied to the pen nib is Y [mm], the line width when the initial load (Lx) is applied to the pen nib is X [mm], and the line width when an intermediate load (Lz = 0.5Ly), which is half the load required to open the valve mechanism, is applied to the pen nib is Z [mm], and Y / X > 3 and Z / X > 2.

2. The valve-operated writing instrument according to claim 1, characterized in that the pen nib is made of synthetic fibers bundled together in a cylindrical shape, with both ends in the longitudinal direction formed into conical shapes, and one end in the longitudinal direction constituting the pen tip.

3. The valve-operated writing instrument according to claim 1 or 2, wherein a cap is provided that is detachably attached to the front end of the barrel, the cap having a cap body that covers the pen nib and a decorative member that covers a part of the outside of the cap body, and the cap body and the decorative member are formed by two-color molding.

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