JP7783706B2 - Writing refills - Google Patents

Description

This invention relates to a group of writing refills and writing implements that make it easy to distinguish differences in ink consumption between multiple writing refills containing ink of the same hue.

For example, a writing refill (ballpoint pen refill) used in a ballpoint pen writing instrument is generally attached by press-fitting a ballpoint pen tip or a coupling member that supports the ballpoint pen tip as a writing part into one end (front end) of an ink reservoir tube.
The ink reservoir tube is made of a transparent or semi-transparent resin material, such as polypropylene, to ensure ease of molding and visibility of the ink amount.

A typical ink reservoir tube molded from a resin material such as polypropylene often has an outer diameter of about 3 mm and an inner diameter of about 1.8 mm, as described in paragraph [0021] of Patent Document 1, for example.
The ink reservoir tube shown in this example is relatively thick, so there is a limit to the amount of ink that can be stored in the ink reservoir tube, which results in a practical problem in that it is not possible to obtain a sufficient writing distance.

The applicant has therefore proposed a thin-walled writing refill in which the outer diameter of the ink reservoir tube is roughly the same as that of the conventional refills described above, but the inner diameter of the ink reservoir is enlarged. This is disclosed in Patent Documents 2 and 3.

Japanese Patent Application Laid-Open No. 2000-198291 International Publication No. WO2017/061570 International Publication No. WO2018/180679

However, in this type of writing refill that uses the ink reservoir tube described above, different ball diameters are available for the writing portion, and due to the difference in ball diameter, each writing refill consumes different amounts of ink for a given writing distance.
However, these writing refills are generally formed to have substantially the same external size, except for the tip of the writing part.

Therefore, in order to select the desired writing refill from a group of writing refills that have multiple writing refills with different ink consumption amounts per unit writing distance, one must choose a method such as visually identifying the fine writing tip or identifying it by reading small text information written on the surface of the ink reservoir tube, etc.
However, it is virtually impossible for an average user to visually check the minute writing tip (for example, ball diameter) to determine whether or not the writing refill is the one they want. Furthermore, even if they try to read the text information written on the ink reservoir, the small text information makes it easy to misread, making it practically impossible to accurately select the writing refill they want.

The object of this invention is to provide a group of writing refills and a group of writing implements that house these refills in a barrel, in which differences in ink consumption per unit writing distance between multiple writing refills containing ink of the same hue can be easily identified.

The group of writing refills according to the present invention, which has been made to solve the above-mentioned problems, comprises writing refills in which a coupling member that supports a writing portion is attached to one end of a transparent or translucent ink reservoir tube, and ink is contained within the tube of the ink reservoir tube, and in which, among the components of the writing refill, the coupling member and the tail plug attached to the other end of the ink reservoir tube are the same, and the outer diameter of the ink reservoir tube of the writing refill and the overall length of the writing refill are the same, the ink reservoir tubes contain ink of the same hue, and the inner diameter of the ink reservoir tube is varied depending on the amount of ink consumed per unit writing distance of the writing refill, thereby varying the color difference of each ink reservoir tube.

In this case, in one preferred embodiment, the ink reservoir tubes contain the same type of black ink, such as oil-based or water-based ink, and are configured so that the difference in lightness (L*) from the outer surface of each ink reservoir tube is equal to or greater than [difference in ink reservoir tube thickness (mm) x 10], depending on the amount of ink consumed per unit writing distance of the writing refill.

In a more preferred embodiment, a backflow preventer is contained at the rear end of the ink at the other end of the ink reservoir tube, and the viscosity of the backflow preventer is selected to vary depending on the inner diameter of the ink reservoir tube.

The writing instrument group according to this invention comprises a plurality of writing instruments each having a barrel housing the above-mentioned writing refill, and the barrels are combined so that their wall thicknesses vary depending on the amount of ink consumed per unit writing distance by the writing refill housed in the barrel.

In the writing refill group according to the present invention described above, the ink reservoirs contain ink of the same type and hue, and the color difference between each ink reservoir varies depending on the amount of ink consumed per unit writing distance of the writing refill, making it easy to select the desired writing refill.

In addition, the writing instrument group of this invention consists of a plurality of writing instruments, each of which contains a writing refill that constitutes the writing refill group described above, housed in a barrel, and the barrels are combined so that the thicknesses of the barrels differ depending on the amount of ink consumed per unit writing distance of the writing refill.
Therefore, since the transmittance of the barrel, for example, changes and the color difference (brightness) of each ink reservoir tube housed in the barrel also differs, the desired writing implement can be easily selected.
Furthermore, by molding the ink reservoir tube to be thin, the amount of resin used can be reduced, which contributes to reducing the environmental impact.

1 shows the external configuration of a group of writing refills according to the present invention, with (A) to (C) showing ballpoint pen refills with different ink consumption amounts per unit writing distance. 2A to 2C are cross-sectional views taken along the axial direction of each of the ballpoint pen refills shown in FIG. 1A to 1C. 2A and 2B show the individual components of the tail plug to be attached to the ink reservoir tube of the ballpoint pen refill shown in FIG. 1, where (A) is a perspective view seen from the front end, (B) is a perspective view seen from the rear end, (C) is a front view, and (D) is a plan view. 2 is a perspective view showing the writing instrument in a state in which one of the ballpoint pen refills shown in FIG. 1 is housed in a barrel. FIG. In the writing implement shown in FIG. 4, (A) is a plan view, (B) is a front view, and (C) is a cross-sectional view along the axial direction.

The writing refills and writing implements of this invention will be described based on the embodiments shown in the drawings.

<Ballpoint pen refills (writing refills)>
First, Figures 1(A) to 1(C) and Figures 2(A) to 2(C) show examples of ballpoint pen refills that make up a group of writing refills, and the same alphabetical symbols in Figures 1 and 2 show the same ballpoint pen refill in external view and cross-sectional view.
This ballpoint pen refill 1 is attached by press-fitting an ink reservoir 2 to one end (front end) of the ink reservoir 2 and a coupling member 4 supporting a ballpoint pen tip 3 as a writing part. A tail plug 5 is fitted and attached to the other end (rear end) of the ink reservoir 2.

In addition, ink 6 is contained in the ink reservoir 2 from immediately after the coupling member 4 toward the rear end, and a grease-like ink backflow preventive body 7 is contained in contact with the rear end of the ink 6 toward the tail plug 5.
In this embodiment, the coupling member 4 with the ballpoint pen tip 3 already attached thereto is press-fitted into one end of the ink reservoir 2, but a ballpoint pen refill 1 in which the ballpoint pen tip 3 is attached directly to the front end of the ink reservoir 2 without using the coupling member 4 can also be suitably used.

For the sake of convenience, the ballpoint pen refills 1 shown in FIGS. 1 and 2 (A), (B), and (C) will be referred to as the first refill, the second refill, and the third refill, respectively.
In the first to third refills, the writing balls 3a, 3b, and 3c provided at the tip of each ballpoint pen tip 3 have ball diameters of 1.0 mm, 0.7 mm, and 0.5 mm, respectively, and thus ballpoint pen tips 3 set to different ink flow rates are used.
Each of the writing balls 3a, 3b, and 3c is pressed toward the tip by a coil spring 3d housed in each ballpoint pen tip 3. As a result, when no writing is being performed, the writing balls 3a, 3b, and 3c act to close the tip of the ballpoint pen tip 3.

The inner diameters of the central portions of the ink reservoir 2 in the first to third refills are different, with the inner diameters having a relationship of d1>d2>d3 as shown in Figure 2. As a result, the first to third refills 1 are set so that the amount of ink 6 consumed along the length of the ink reservoir 2 at the same writing distance is approximately the same.
The rear portion of the ink 6 inside the ink containing tube 2 is filled with an ink backflow preventive material, and the viscosity of this ink backflow preventive material varies depending on the inner diameter (d1, d2, d3) of the ink containing tube 2. Specific examples are shown in Examples 1 and 2 described below. It is preferable that the viscosity of the ink backflow preventive material decreases in proportion to the inner diameter of the central portion of the ink containing tube.

The ink reservoir 2 of the first to third refills is molded in a straight line from transparent or translucent polypropylene resin, and the outer diameter is the same for all first to third refills 1. Furthermore, the overall lengths of the first to third refills 1 are also the same. By making them the same shape, the first to third refills 1 can be housed in the same common barrel of a writing instrument.

As shown in FIG. 2, the ink reservoir 2 of the first refill has a large inner diameter d1, and therefore has connecting portions 2a and 2b at both ends that are thicker toward the axial center.
Furthermore, the ink containing tube 2 of the second refill has an inner diameter d2 that is slightly smaller than the inner diameter of the ink containing tube 2 of the first refill, and therefore has connecting portions 2a and 2b at both ends that are thinner toward the axial center.
Furthermore, the ink reservoir 2 of the third refill has an inner diameter d3 at both ends of the connecting portions 2a and 2b, which is the same as the inner diameter of the central portion, and is formed in a straight shape.
With this configuration, the inner diameters of the connecting portions 2a, 2b formed at the ends of the ink containing tubes 2 of the first to third refills are the same, so that the common coupling members 4 and tail plugs 5 can be fitted to the ink containing tubes 2 without regard to front-to-back orientation.

2, the coupling member 4 is a cylindrical body whose front half is tapered to slightly reduce its outer diameter, and has an insertion hole 4a for the ballpoint pen tip 3 formed toward the front. An annular groove 4b is formed toward the rear, and an ink introduction hole 4c for the ballpoint pen tip 3 is opened in the central shaft portion.
By inserting one end (front end) of the ink reservoir 2 into the annular groove 4b, the inner and outer diameter sides of the connecting portion 2a of the ink reservoir 2 are press-fitted between the inner and outer surfaces of the annular groove 4b of the coupling member 4. This increases the attachment strength.

Figure 3 shows the individual configuration of the tail plug 5 that is attached to the other end (rear end) of the first to third refills 1. The front half of this tail plug 5 forms a cylindrical section 5a, its axial hole forming an air vent 5b, and a stepped section 5c with an enlarged diameter is formed in the center. The rear half, whose diameter is enlarged by the stepped section 5c, has three legs 5d divided along the circumference and formed with equal lengths along the axial direction, and the tail end of each leg 5d is formed with an arc-shaped inclined surface 5e that slopes outward from the circumference. It is preferable that this tail plug 5 be made of a resin material.

The tail plug 5 is attached to the ink reservoir 2 by inserting the cylindrical portion 5a into the connecting portion 2b at the rear end of the ink reservoir 2. In this case, the position of the tail plug 5 relative to the ink reservoir 2 is achieved by the step portion 5c coming into contact with the rear end of the ink reservoir 2. In this state, the air vent 5b provided in the tail plug 5 functions to exchange air as the ink in the ink reservoir 2 decreases.
In addition, the leg 5d of the tail plug 5 and the inclined surface 5e formed at its tail end have flexibility that causes the leg 5d to bend inward when subjected to strong writing loads or the impact of being dropped when the ballpoint pen refill 1 is stored in the barrel tube described below.

In the first to third refills 1 described above, when achromatic ink such as black is used, as will be explained later, the greater the ink consumption, the different the hue (lower the brightness) of the ink from the ink storage tube 2.
By changing the gradation of the hue in this way, in a group of ballpoint pen refills arranged in the same type of barrel, it is possible to easily and intuitively judge the difference in ball diameter and instantly pick up (select) the ballpoint pen refill without having to remove the tip or tail plug of the tiny ballpoint pen tip and check the cross section of the ink reservoir tube from the rear end.

In addition, the first to third refills 1 described above are designed to be used by users who are visually impaired and have difficulty distinguishing between hues, and as shown in Figure 1, an engraving 2c is made inside the ink reservoir 2 between the ink backflow prevention body 7 and the tail plug 5, making it easier to distinguish between the first to third refills.
That is, in this embodiment, the first refill has two markings 2c perpendicular to the axis, the second refill has one marking 2c perpendicular to the axis, and the third refill has no markings.

<Refill group brightness (hue)>
Next, the refills constituting the group of ballpoint pen refills were divided according to the amount of ink consumed per unit writing distance, and various characteristics including the lightness (hue) of each were measured.

To measure the lightness, five refills each having the same ball diameter were attached to white fine paper conforming to JIS P3201, and the lightness value L* was measured from the surface of a component such as an ink reservoir tube using a device such as a color meter (SC-P, manufactured by Suga Test Instruments Co., Ltd.).
The measurement conditions when using the color meter (SC-P, manufactured by Suga Test Instruments Co., Ltd.) in the above embodiment are as follows:
[Optical conditions] Reflection measurement: Diffuse light illumination, 8° reception (compliant with JIS Z 8722 condition c), trap: de: 8° (specular reflection component not included), measurement hole: φ15 mm
[Light source field of view] D65/2
[Color system] L*a*b*c*
[Stability] ΔE*ab <0.01
[Light source] VI-LED (high color rendering white LED)

Example 1
Measurements were conducted on five of two types of writing refills (ballpoint pen refills) with different ink consumption per unit writing distance, and the results are shown in Table 1. The measured values for ink consumption, viscosity of the backflow preventer, and brightness are average values.

Example 2
Measurements were carried out on five of each of three types of writing refills (ballpoint pen refills) with different ink consumption per unit writing distance. The results are shown in Table 2. The measured values for ink consumption, viscosity of the backflow preventer, and brightness are average values.
The ballpoint pen refills shown in this embodiment correspond to the first to third refills described with reference to FIGS.

In both Examples 1 and 2, inks of the same type and hue (black) with the following composition were used.
Carbon black #25 (manufactured by Mitsubishi Chemical): 10% by weight
Polyvinyl butyral (BL-S, manufactured by Sekisui Chemical): 5% by weight
Terpene phenol resin (YP90L, manufactured by Yasuhara Chemical): 8% by weight
Polypropylene glycol (average molecular weight: 4000): 5% by weight
Phosphate ester (Plysurf A208B): 1.47% by weight
Amine compound (polyoxyethylene alkylamine: AMIET105): 1.03% by weight
3-Methoxybutanol: 5% by weight
3-Methoxy-3-methyl-1-butanol: 64.5% by weight
The viscosity of the backflow preventive material is measured in an environment of 25°C at a shear rate of 3.8/s.

From Tables 1 and 2, it can be seen that the lightness (L*) changes depending on the amount of ink consumed per unit writing distance of each writing refill, that is, in this embodiment, the thickness of the ink reservoir 2.
Furthermore, in each example, the difference in brightness value fell within a range that satisfied the requirement of the difference in thickness (mm) of the ink containing tube 2 x 10 or more, and it was confirmed that there was a difference in the relative numerical values, and that the change in gradation was clearly identifiable even with the naked eye.

The above measurement results show the results when using ink of the same type and black hue (achromatic color) with the same ink composition. However, when using color inks of different hues, such as red, green, or blue, it was found that, within the range of inks of the same type and hue, the color difference similarly changes depending on the thickness of the ink reservoir tube. This confirms that it is possible to easily select the desired writing refill based on differences in color difference.

<Ink composition>
Preferred ink compositions for use in each ballpoint pen refill of the writing refill group according to the present invention include those shown below.

The ink used in each of the ballpoint pen refills is a black ink whose main solvent (at least 50% by weight of the total solvents) is a solvent selected from alcohols, polyhydric alcohols, and glycol ethers, each of which has a vapor pressure of at least 0.001 mmHg at 25°C. The use of a specific solvent with such a high vapor pressure makes it possible to provide an oil-based ballpoint pen with an excellent, smooth writing feel. The ink composition was developed with the aim of resolving the problems that are unique to the use of such specific solvents with high vapor pressures. A main solvent is one that contains at least 50% by weight of the total solvents.

Specific examples of alcohols include aliphatic alcohols with two or more carbon atoms, such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butyl alcohol, 1-pentanol, isoamyl alcohol, sec-amyl alcohol, 3-pentanol, tert-amyl alcohol, n-hexanol, methylamyl alcohol, 2-ethylbutanol, n-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-octanol, 2-ethylhexanol, 3,5,5-trimethylhexanol, nonanol, n-decanol, undecanol, n-decanol, trimethylnonyl alcohol, tetradecanol, heptadecanol, cyclohexanol, 2-methylcyclohexanol, benzyl alcohol, and many other higher alcohols.

Furthermore, examples of polyhydric alcohols include polyhydric alcohols having two or more carbon atoms and two or more hydroxyl groups in the molecule, such as ethylene glycol, diethylene glycol, 3-methyl-1,3-butanediol, triethylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexylene glycol, and octylene glycol.

Glycol ethers include methyl isopropyl ether, ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether, butyl ether, hexyl ether, 2-ethylhexyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and tetraethylene glycol monobutyl ether. ether, 3-methyl-3-methoxy-1-butanol, 3-methoxy-1-butanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol phenyl ether, propylene glycol tert-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monobutyl ether, etc.

Among the solvents listed above, glycol ethers having 2 to 7 carbon atoms are particularly preferred, as their effects are particularly clear. In addition, from the viewpoints of safety and oral toxicity, it is preferable to use organic solvents other than ethylene glycol derivatives.
In addition to the solvents listed above, the following solvents may be added to the mixture of phosphoric acid ester and amine compound within a range that does not impair the solubility of the mixture and the performance of the mixture.
Examples of such derivatives include polyhydric alcohol derivatives, such as sorbitan fatty acid derivatives, polyglycerin higher fatty acid derivatives, sucrose fatty acid derivatives, and propylene glycol fatty acid derivatives.

Examples of ester solvents include propylene glycol methyl ether acetate, propylene glycol diacetate, 3-methyl-3-methoxybutyl acetate, propylene glycol ethyl ether acetate, ethylene glycol ethyl ether acetate, butyl formate, isobutyl formate, isoamyl formate, propyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, propyl propionate, isobutyl propionate, isoamyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, Examples of various esters include methyl valerate, ethyl valerate, propyl valerate, methyl isovalerate, ethyl isovalerate, propyl isovalerate, methyl trimethylacetate, ethyl trimethylacetate, propyl trimethylacetate, methyl caproate, ethyl caproate, propyl caproate, methyl caprylate, ethyl caprylate, propyl caprylate, methyl laurate, ethyl laurate, methyl oleate, ethyl oleate, caprylic acid triglyceride, tributyl acetate citrate, octyl oxystearate, propylene glycol monoricinoleate, methyl 2-hydroxyisobutyrate, and 3-methoxybutyl acetate.

Specific examples of diether and diester solvents that do not have a hydroxyl group in the molecule include ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and dipropylene glycol dimethyl ether.

The colorant (coloring material) is not limited, but it is preferable to use a pigment or a combination of a pigment and a dye. The use of a pigment has the effect of providing excellent fastness. Pigments that can be used include carbon black, phthalocyanines, insoluble azos such as monoazos, disazos, condensed azos, and chelate azos, and soluble azos such as sparingly soluble azos and soluble azos, as well as organic pigments such as quinacridones, diketopyrrolopyrroles, threnes, dioxazines, and isoindolinones.

In particular, carbon black with a specific surface area as small as possible should be used, preferably 100 m ² /g or less as measured by the BET method. Specific examples of carbon black manufactured by Mitsubishi Chemical include #33, #32, #30, #25, and CF9; carbon black manufactured by Cabot Corporation include REGAL (400R, 500R, 330R, and 300R), ELFTEX (8 and 12), and STERLING R; carbon black manufactured by Degussa Corporation include Printex (45, 40, 300, 30, 3, 35, 25, 200, A and G), and SB (250 and 200); and carbon black manufactured by Columbian Chemical Company include RAVEN (1040, 1035, 1020, 1000, 890, 890H, 850, 500, 450, 420, 410, H20, 22, 16, and 14).

The pigment is preferably one that is difficult to dissolve in the organic solvent used and has an average particle size of 30 to 700 nm after dispersion. The pigment can be blended in an amount of 0.5 to 25% by weight, preferably 0.5 to 20% by weight, based on the total weight of the ink composition, as needed.

Pigments can be used alone or in combination of two or more types. If necessary, inorganic pigment dispersions or dyes can also be added to the extent that they do not adversely affect dispersion stability. The use of dyes has the effect of providing excellent color development. Other examples include resin emulsions obtained by polymerizing styrene, acrylic acid, acrylic acid esters, methacrylic acid, methacrylic acid esters, acrylonitrile, and olefin-based monomers; hollow resin emulsions that swell and become amorphous in ink; and organic multicolor pigments made of dyed resin particles obtained by dyeing these emulsions themselves with a colorant.

When the colorant used in this embodiment is a pigment, various conventionally known methods can be used to produce the pigment dispersion ink composition. For example, the pigment dispersion ink composition can be easily obtained by blending the above components and mixing and stirring them using a stirrer such as a dissolver, or by mixing and grinding them using a ball mill, roll mill, bead mill, sand mill, pin mill, etc., and then removing coarse pigment particles, undissolved matter, and contaminating solids by centrifugation or filtration.

Dyes used in combination with these pigments can be used without any particular restrictions, as long as they do not destroy the dispersion system. These dyes include direct dyes, acid dyes, basic dyes, mordant/acid mordant dyes, alcohol-soluble dyes, azoic dyes, sulfide/sulfide vat dyes, vat dyes, disperse dyes, oil-soluble dyes, food dyes, metal complex dyes, and other dyes used in ordinary dye ink compositions, as well as any of the inorganic and organic pigments used in ordinary pigment ink compositions. The blending amount is selected from the range of 1 to 50% by weight of the total composition.

Resins are used in oil-based ink compositions. Resins used in oil-based ink compositions are added for purposes such as viscosity adjustment and reducing pen tip wear, but when pigments are included, they are also used as dispersants. Examples of such resins include ketone resins, styrene resins, styrene-acrylic resins, terpene phenolic resins, rosin-modified maleic acid resins, rosin phenolic resins, alkylphenol resins, phenolic resins, styrene-maleic acid resins, rosin-based resins, acrylic resins, urea aldehyde-based resins, maleic acid-based resins, cyclohexanone-based resins, polyvinyl butyral, polyvinylpyrrolidone, and other representative resins.

The amount of these resins to be blended is preferably 1 to 30% by weight, and more preferably 1 to 20% by weight. If the blending amount is less than 1% by weight, it becomes difficult to adjust the viscosity and prevent wear at the pen tip, while if it exceeds 30% by weight, it may become impossible to blend in raw materials other than the resin, or it may have a negative impact on the writing feel.

In a preferred embodiment, when a pigment is used as the colorant in the ink composition, the dispersant used can be selected from the resins listed above that are capable of dispersing the pigment, and any type of surfactant or oligomer can be used as long as it suits the purpose. Specific dispersants include synthetic resins such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl butyral, polyvinyl ether, styrene-maleic acid copolymer, ketone resin, hydroxyethyl cellulose and its derivatives, and styrene-acrylic acid copolymer, as well as PO/EO adducts and polyester amine oligomers.

When the ink is an oil-based ink composition, it contains a phosphate ester neutralizer. The phosphate ester neutralizer has the effect of making it easier to remove ink deposits from the ball surface, thereby preventing smearing of the writing when starting to write. In this embodiment, it works in conjunction with polypropylene glycol to prevent smearing of the writing when starting to write for a short or long period of time, and also has the effect of smoothing the ink transfer when writing at low speeds.

The phosphate esters used typically consist of phosphate monoesters, diesters, and trace amounts of triesters, and most surfactants have two types of ester structures: aromatic and aliphatic. Regarding the alkyl groups that can form the phosphate ester structure, alkyl groups derived from natural or synthetic higher alcohols are used. Phosphate esters with an alkyl group containing 10 to 20 carbon atoms and 0 to 50 polyoxyethylene chains are used. Phosphate esters with an alkyl group containing 15 to 20 carbon atoms and 0 to 4 polyoxyethylene chains are particularly preferred. Furthermore, it is preferable to neutralize with an amine-based compound such as alkanolamine, polyoxyethylene alkylamine, amphoteric surfactant, or fatty amine.

The amount of these additives added is preferably 0.01% to 15% by weight of the neutralized mixture relative to the total amount of the ink composition, more preferably 0.1 to 10% by weight. Furthermore, 0.1 to 8% by weight is particularly preferred. If the amount is less than 0.01% by weight, the effect of making it easier to remove ink deposits from the ball surface will be reduced, and if the amount is more than 15% by weight, the ink may be repelled too much from the ball, which may result in poor line quality and problems such as line breakage.

When the ink is an oil-based ink composition, it is desirable to add polypropylene glycol. This addition has the effect of reducing smearing when starting to write. This phenomenon not only reduces smearing achieved by ink repelling onto the metal ball, but also makes it more difficult for an ink film to form, making it possible to reduce smearing over a short period of 1 to 20 minutes.

The molecular weight of polypropylene glycol is preferably as large as possible, as this allows for a smaller amount to be added and improves the drying properties of drawn lines. A molecular weight (calculated molecular weight) of 1,000 or more is preferred, 2,000 or more is more preferred, and 4,000 or more is even more preferred.

The amount of polypropylene glycol added is preferably 0.01% to 10% by weight, and especially preferably 0.1% to 10% by weight. In this range, pigment-based inks that dry easily are less likely to form an ink film on the metal ball, which is highly effective in preventing smearing when starting to write.

If the amount added is outside this range and is less than 0.1% by weight, the effect will be poor and the ball may not spin. If the amount added is more than 10% by weight, the non-volatile components in the ink will be too high, which may reduce the drying speed of the lines drawn or make them more susceptible to bleed-through, depending on the raw materials used.

In addition, in this embodiment, if necessary, anti-rust agents, anti-fungal agents, surfactants, lubricants, wetting agents, etc. that are compatible with the ink and do not adversely affect the ink can be added. Fatty acids, in particular, are suitable for use as lubricants. Furthermore, non-volatile solvents that are compatible with the main solvent can also be added as drying suppression additives, as long as they do not adversely affect the product characteristics.

<Writing Instruments (Ballpoint Pens)>
Next, Figures 4 and 5 show an example of a writing instrument (ballpoint pen writing instrument) in which one writing refill (ballpoint pen refill) 1 from the ballpoint pen refill group described above is housed in a barrel, and in this example, the first refill 1 shown in Figure 1 (A) is used.
The barrel 12 constituting the writing instrument 11 shown in Figures 4 and 5 is formed by molding a sheet of synthetic resin, such as polycarbonate, polypropylene, or polyethylene terephthalate. That is, a repeating pattern of multiple recesses and protrusions is formed on both sides of the sheet, and the barrel 12 is formed by welding both ends of the sheet so that the entire body is cylindrical. Then, a front joint 13 and a rear joint 14, each made of a resin material and cylindrically shaped, are attached to both ends of the barrel 12.

The barrel 12 is formed by another manufacturing method in which a cylindrically formed sheet material is strongly sandwiched between two rollers having predetermined irregularities and disposed inside and outside the cylinder with an axis parallel to the cylinder, thereby forming creases.Furthermore, the barrel 12 may be formed by blow molding.
The wall thickness of the formed barrel 12 is preferably less than 1 mm, and a wall thickness of 0.35 mm, for example, is also practical. In addition, since the barrel 12 is manufactured from sheet material, the wall thickness of the barrel 2 is approximately uniform overall.
The barrel 12 is connected to the front joint 13 and the rear joint 14 by, for example, adhesive or welding.

The barrel 12 described above is less likely to deform and has higher rigidity when subjected to a force applied in the direction of the central axis when gripped by a user, compared to a barrel formed in a cylindrical shape with the same thickness and no irregularities. Furthermore, the barrel 12 is thinner and lighter than a barrel formed in a cylindrical shape with no irregularities so as to have the same rigidity when subjected to a force applied in the direction of the central axis when gripped. Furthermore, the barrel 12 has an outer surface with a regularly irregular shape made up of a combination of three-dimensional polygonal unit patterns, which also has a decorative effect.

A conical tip portion 15 is detachably attached by a screw connection using a front joint 13 attached to the barrel 12. An opening 15a is provided at the tip of this tip portion 15, and the writing portion (ballpoint pen tip) 3 of the ballpoint pen refill 1 appears and disappears through the tip opening 15a by a knock operation, which will be described later.
A cylindrical member 16 is attached to the barrel 12 using a rear joint 14, and a clip 16a is formed integrally with the cylindrical member 16. A knock operation portion 17 is disposed at the rear end of the cylindrical member 16 in a protruding state.

5(C) shows this writing instrument 11 in a cross section taken along the axial direction, with a coil-shaped return spring 18 attached inside the tip portion 15. Therefore, by removing the tip portion 15 from the front joint 13, storing the ballpoint pen refill 1 inside the barrel 12, and screwing the tip portion 15 onto the front joint 13, the return spring 18 comes into contact with the joint member 4 of the ballpoint pen refill 1.
As a result, a biasing force is applied to the ballpoint pen refill 1 by the return spring 18 in the direction toward the rear end within the barrel 12 .

Furthermore, a rotor 19 is mounted within the cylindrical member 16, and a truncated cone-shaped recess 19a having a slope that reduces the inner diameter toward the bottom is formed at the front end of the rotor 19, and the tail plug 5 of the ballpoint pen refill 1 is inserted and positioned within this recess 19a.
On the other hand, the knock operating part 17 is arranged to cover the shaft extending to the rear of the rotor 19, and the rotor 19 and the knock operating part 17 are arranged in a retracted position by the force of the return spring 18 via the ballpoint pen refill 1.
Therefore, by knocking the knock operation portion 17, the rotor 19 and the ballpoint pen refill 1 move forward in the axial direction against the biasing force of the return spring 18.

A cam member consisting of multiple ribs along the axial direction is formed within the cylindrical member 16, and together with the rotor 19 that abuts against this cam member, a rotary payout mechanism known as a knock mechanism is formed.
As a result, each time the knock operation unit 17 is operated, the ballpoint pen refill 1 moves forward together with the rotor 19, and the ballpoint pen tip 3 as the writing part is repeatedly set in a writable state in which it protrudes from the tip opening 15a, and the ballpoint pen refill 1 moves back together with the rotor 19, and the ballpoint pen tip 3 is stored in the tip opening 15a.

In addition, when the ballpoint pen tip 3 is in a writable state protruding from the tip opening 15a of the nozzle 15, the tail plug 5 is inserted into the truncated cone-shaped recess 19a of the rotor 19. When a writing load is applied in this state, the inclined surfaces 5e formed on the legs 5d of the tail plug 5 come into contact with the inclined surfaces of the truncated cone-shaped recess 19a on the rotor 19, acting to deflect each leg 5d in the axial direction. This provides a cushioning effect to the ballpoint pen refill 1 in the axial direction.
Therefore, it is possible to easily absorb the vertical load applied during writing, and to prevent deformation (buckling or bending) of the thin-walled ink reservoir tube 2.

According to the writing implement described above, the thickness of the barrel 12 can be made thinner than before, so that the writing refill 1 can be seen through the barrel 12 to some extent.
Therefore, by creating a group (set) of writing implements that employs a combination of different barrel thicknesses 12 according to the ink consumption per unit writing distance of the writing refills 1 housed in the barrel 12, the difference in appearance visibility between the writing refill groups can be further emphasized.

1. Writing refill (ballpoint pen refill)
2 Ink reservoir tube 3 Writing part (ballpoint pen tip)
3a to 3c Writing ball 4 Joint member 5 Tail plug 6 Ink 7 Ink backflow prevention body 11 Writing implement 12 Barrel 13 Front joint 14 Rear joint 15 Tip portion 16 Cylindrical member 17 Knock member 18 Return spring 19 Rotor

Claims (1)

A group of writing refills in which a coupling member supporting a writing part is attached to one end of a transparent or translucent ink reservoir tube, and ink is contained within the ink reservoir tube, wherein, among the components of the writing refill, the coupling member and the tail plug attached to the other end of the ink reservoir tube are the same, and the outer diameter of the ink reservoir tube and the overall length of the writing refill are the same,
A group of writing refills characterized in that the ink containing tubes contain ink of the same hue, and the color difference of each ink containing tube is made different by varying the inner diameter of the ink containing tubes according to the amount of ink consumed per unit writing distance of the writing refill.