JP7408318B2 - Ballpoint pen refills and ballpoint pens - Google Patents

Description

The present invention relates to a ballpoint pen refill. Furthermore, the present invention relates to a ballpoint pen refill and a ballpoint pen that can form handwriting with excellent glitter and color development on paper over a long period of time.

BACKGROUND ART Water-based ballpoint pens that produce brushstrokes with metallic luster have been known and are widely used for everything from writing to drawing. Such ballpoint pens often use plate-shaped glittering pigments such as plate-shaped (scale-shaped) metal powder or pearl pigments as reflective pigments in the ink components because of the high brightness of the resulting handwriting. .
In addition, in order to adjust the hue of the ink, general-purpose pigments are added to the ink or the surface of the plate-like bright pigment is colored (for example, Patent Document 1, (see 2).
As described in Patent Document 1, when a general-purpose coloring pigment is added to the ink, the paper surface has permeability, so only the plate-shaped bright pigment with a large particle size is exposed to the paper surface during writing. The colored pigments penetrate into the paper surface, making it difficult to obtain handwriting with the desired hue. In addition, if a plate-shaped glitter pigment whose surface has been colored is used, there is no need to consider the penetration of the colored pigment described above, but in order to color the entire ink, the plate-shaped glitter pigment used must be Since it is necessary to increase the particle size of the ink and to increase the amount added, the plate-like bright pigment tends to settle during storage and the ink dischargeability tends to deteriorate.

By the way, in recent years, multicolor (multi-core) ballpoint pens, in which ballpoint pen refills of multiple colors are housed in the barrel, have become popular because it is possible to form handwriting in different tones such as black, red, and blue with a single ballpoint pen. It is used for. Ballpoint pens with thin barrels tend to be preferred from the viewpoint of ease of use, but such ballpoint pens often accommodate slender refills because the internal volume of the barrel is small. However, with slender refills, the ink storage tube included in the refill is often slender and thin, and depending on the material of the ink storage tube, the ability to suppress the permeation of volatile solvents such as water may become poor over time. Volatile solvents from the ink permeate through the ink storage tube and volatilize out of the refill, which tends to cause the ink to thicken excessively, and ink insoluble components to aggregate, resulting in poor ink discharge performance. The above-mentioned tendency is remarkable in the case of an ink storage tube made of synthetic resin such as polyethylene terephthalate (PET), and furthermore, when the ink uses a glitter pigment as a coloring agent, the ink can produce handwriting with excellent glitter. In many cases, a large amount of plate-like bright pigment is added to enable the formation of pigments, but inks containing a large amount of solid content such as pigments have a relatively small liquid content, so when the solvent evaporates, Ink viscosity increase and solid content agglomeration were significant, and ink dischargeability was more likely to deteriorate.

As described above, ballpoint pens using plate-like bright pigments as inks sometimes have difficulty in achieving good writing performance and stability over time, so improvements are desired.

Japanese Patent Application Publication No. 11-29734 Japanese Patent Application Publication No. 2003-12973

The present invention provides a ballpoint pen refill that is equipped with a slender, thin-walled ink storage tube and contains high-brightness water-based ink using plate-shaped glitter pigments, and is capable of achieving glitter and color development on paper surfaces of various hues. To provide a ballpoint pen refill capable of stably forming bright handwriting over a long period of time with excellent properties and suppressed blurring and breakage, and a ballpoint pen containing the refill.

The ballpoint pen refill of the present invention includes a pen tip and an ink storage tube, a water-based ink composition is stored in the ink storage tube, and an ink backflow preventer is filled in the end surface of the water-based ink composition. hand,
The water-based ink composition contains water, a water-soluble organic solvent, a plate-like bright pigment, a colored pigment, and a water-dispersible acrylic acid polymer, a urethane polymer, and an olefin polymer selected from one or more water-dispersible polymers and a thickener;
The viscosity of the aqueous ink composition at 20° C. is 800 to 1600 mPa·s at 3.84 sec ⁻¹ ,
The aqueous ink composition has a shear thinning index n of 0.15 to 0.5 at 20°C,
The ink storage tube is made of synthetic resin, and has an outer diameter of 2.5 to 4 mm and a wall thickness of 0.3 to 1 mm.
Furthermore, it is required that the content of the water be 40 to 80% by mass and the content of the organic solvent be 1 to 20% by mass with respect to the total mass of the aqueous ink composition.
When the sum of the total mass of the plate-like bright pigment and the total mass of the colored pigment is A, and the total mass of the water-dispersible polymer is B, B/A is 0.05 to 0.5. The requirement is that
Furthermore, the aqueous ink composition further includes a water-soluble copolymer of acrylic acid and a sulfonic acid monomer.
Further, when the total mass of the water-dispersible polymer is X, and the total mass of the copolymer of acrylic acid and sulfonic acid monomer is Y, Y/X is 0.1 to 1.0. It is a requirement that there be.
Furthermore, the pen tip is required to include a ball having an outer diameter of 0.2 to 0.7 mm.
Furthermore, the pen tip is a pipe-type ballpoint pen tip, and the ballpoint pen tip has a straight cylindrical pipe at the tip, and the outer diameter and the inner diameter are enlarged at the rear of the tip. The requirement is that it has a shape that
Furthermore, a ballpoint pen containing the ballpoint pen refill is required.
Furthermore, the ballpoint pen is a compound type retractable ballpoint pen in which a plurality of ballpoint pen refills are accommodated in a barrel, and the writing tip of one of the ballpoint pen refills comes out and retracts from the front end opening of the barrel by actuation of a retracting mechanism. It is a requirement that there be.

According to the present invention, even a ballpoint pen refill equipped with a slender, thin-walled ink storage tube and containing high-brightness water-based ink using plate-shaped glitter pigments can be used to improve glitter and color development on paper surfaces of various hues. To provide a ballpoint pen refill capable of stably forming bright handwriting with excellent quality and suppressed blurring and breakage over a long period of time, and a ballpoint pen containing the refill.

FIG. 2 is a sectional view showing an example of a ballpoint pen refill of the present invention. It is a sectional view showing an example of the pen tip (ballpoint pen tip) with which the ballpoint pen refill of the present invention is provided. 3 is a sectional view taken along line XX in FIG. 2. FIG.

Embodiments of the present invention will be described in detail below. In addition, in this specification, "parts", "%", "ratio", etc. indicating a composition are based on mass unless otherwise specified.

The ballpoint pen refill according to the present invention includes a pen nib and an ink storage tube, and the ink storage tube contains an aqueous ink composition (hereinafter referred to as "ink composition" or "composition" as the case may be) containing a plate-like glitter pigment. ) is housed therein, and an ink backflow preventer is filled in the end surface of the aqueous ink composition. Each element constituting the ballpoint pen refill according to the present invention will be explained below.
The average particle diameter of the plate-shaped pigment in the present invention is a value calculated by setting the minimum value of the particle diameter axis in the particle size distribution diagram as 0.5 μm when measured by a laser diffraction method (volume basis).

The water-based ink composition includes water, a water-soluble organic solvent, a plate-like bright pigment, a colored pigment, and one or more kinds of acrylic acid-based polymers, urethane-based polymers, and olefin-based polymers having water dispersibility. It contains a water-dispersible polymer and a thickener, and has an ink viscosity and shear thinning index within a specific range.

The plate-shaped glittering pigment may be any plate-shaped or scale-shaped pigment that exhibits glittering properties that reflect light in the state of handwriting, and in particular pearl pigments, aluminum pigments, metal or metal oxide coated glass flakes, etc. can be mentioned. One or more of these are selected and blended into the ink.

Specifically, the pearl pigments include natural products such as fish scale foil, and synthetic products such as natural mica, synthetic mica, silica, etc., whose surfaces are coated with metal oxides, and the latter is generally used the most. . Pearl pigments exhibit various color tones depending on the type of metal oxide coated on the mica surface and the coating thickness. Commercially available pearl pigments include, for example, Iriodin 100 (silver), Iriodin 111 (silver), Iriodin 151 (silver), Iriodin 153 (silver), Iriodin 201 (gold), Iriodin 217 (red copper), and Iriodin 289. (blue), 302 (gold), 504 (wine red), Iriodin 530 (copper) [manufactured by Merck Japan Co., Ltd.], Ultimica SB-100 (silver) [manufactured by Topy Industries, Ltd.] [manufactured] etc. Furthermore, there are HELICONE HCS and HELICONE HCXS (manufactured by Wacker Chemie), which are called cholesteric liquid crystal glitter pigments.

The aluminum pigment can be obtained as a paste of fine aluminum particles on very thin scales by crushing and polishing aluminum pieces with a petroleum solvent such as a higher fatty acid or mineral spirit using a ball mill or the like. Commercially available products include Alpaste WXM-0630, EMERAL EMR-D5660, and WJC-U75C (manufactured by Toyo Aluminum Co., Ltd.).
Alternatively, thin film aluminum obtained by vacuum evaporation may be finely ground. Commercially available products include METALURE W-52012 IL, Ultravario Aqua PG-24001 [all manufactured by ECKART], and Elgie neo Silver. #500 (silver color), Gold #500 (gold color) [manufactured by Oike Kogyo Co., Ltd.], etc.

The metal-coated glass flakes are obtained by coating silver and nickel on the glass surface by an electroless plating method, and the metal oxide-coated glass flakes are obtained by coating the surface of glass flakes with titanium dioxide by a liquid phase method. . By changing the thickness of this titanium oxide film, colors such as silver, yellow, red, blue, and green can be obtained. Commercially available metal- or metal oxide-coated glass flakes include Metashine 2040PS, Metashine 2020PS, Metashine 5090NS, and Metashine 5090RC (manufactured by Nippon Sheet Glass Co., Ltd.).

These plate-like bright pigments can be used alone or in combinations of two or more depending on the desired hue and brightness. Further, the amount of the plate-like bright pigment used is in the range of 1.0 to 20% by weight, preferably 1.5 to 10% by weight based on the total amount of the ink composition.

In addition, although there is no particular restriction on the particle size of the plate-like glitter pigment used in the ink composition, it may be difficult to write with the ballpoint pen used, or the pigment may block the ejection groove (ink outflow hole) during writing. A particle size is selected that does not pose a risk of making writing impossible. If the particle size is too small, it will be difficult to obtain a glittering feeling in handwriting, and if it is too large, there will be a strong tendency to inhibit ink ejection performance or promote seat wear. Therefore, a particularly preferable average particle size is 3 to 25 μm. is within the range of

The aqueous ink composition contains one or more water-dispersible polymers selected from acrylic acid polymers, urethane polymers, and olefin polymers. The water-dispersible polymer used is in the form of an emulsion.
The water-dispersible polymer adsorbs to the plate-shaped bright pigment and the color pigment, suppresses the agglomeration of the pigment, and suppresses the deterioration of ink ejectability. A product that adsorbs colored pigments to glittering pigments and paper surfaces, suppresses the colored pigments from penetrating into the interior from the paper surface, and forms handwriting with excellent glittering properties and coloring properties of the colored pigments, with suppressed fading and discontinuities. It is. Note that the water-dispersible polymer may be neutralized with an alkaline substance such as sodium hydroxide, ammonia, or alkanolamine.

Examples of acrylic acid polymers include polyacrylic acid, polycarboxylic acid, acrylic acid/maleic acid copolymer, acrylic acid/sulfonic acid monomer copolymer, acrylic acid/unsaturated carboxylic acid copolymer, and styrene/acrylic acid. Acid copolymers and the like are used.

Specific examples of the acrylic acid polymer include Joncryl PDX-7182, Joncryl PDX-7630A, Joncryl PDX-7692, and Joncryl 7787 (manufactured by BASF Japan), Boncourt 5400EF (manufactured by DIC Corporation), Examples include Movinyl 7525 (manufactured by Nippon Gosei Kagaku Co., Ltd.), Neocryl A-639, Neocryl A-6016 (manufactured by Kusumoto Kasei Co., Ltd.), and one or more of them may be used.

The type of urethane polymer is not particularly limited, and examples include reaction products of polyisocyanate and polyols such as polyether, polyester, and polycarbonate.
In the urethane-based polymer, the amorphous portion and crystalline urethane bond present in the molecule interact with the colored pigment and the plate-like bright pigment, so only the colored pigment is absorbed by the paper surface when writing. This makes it possible to form handwriting with vivid colors and high color development. In particular, self-emulsifying emulsions having anionic functional groups in their molecules are more useful because they exhibit high effects regardless of the pH of the ink.
Specifically, NeoRez R-972, NeoRez R-2170, NeoRez R-966, NeoRez R-967, NeoRez R-986, NeoRez R-9603, NeoRez R-9404 [all manufactured by Kusumoto Kasei Co., Ltd.], Ucoat UX-485, UWS-145, Upren UXA-307 [manufactured by Sanyo Chemical Co., Ltd.], Hydran AP-40N, Hydran APX-101H [manufactured by DIC Corporation], Superflex 150, Superflex 460 , 470, and 820 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and one or more of them may be used.

The type of olefin polymer is not particularly limited, and examples include polyethylene, polypropylene, ethylene-(meth)acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. , these are dispersed in a medium to form an emulsion. In particular, self-emulsifying emulsions having anionic functional groups in their molecules are more useful because they exhibit high effects regardless of the pH of the ink.
Specifically, HYTEC L, HYTEC A, HYTEC A-GH [manufactured by Sumitomo Seika Co., Ltd.], HYTEC E-4A, HYTEC E-5403, and HYTEC E-9460 [all manufactured by Toho Chemical Industries, Ltd.] ] etc., and one or more types may be used.

The emulsion containing the water-dispersible polymer preferably has a film forming temperature (MFT) of 60° C. or higher. The temperature is more preferably 70°C or higher, and even more preferably 80°C or higher.
If the film-forming temperature is within the above range, when the ballpoint pen refill is exposed to excessive temperature changes, the water-dispersible polymer will form a film in the ink, causing the pigment to aggregate and reduce ink ejectability. It is easy to prevent blurred or broken handwriting.

Among the water-dispersible polymers, acrylic acid-based polymers are easily adsorbed not only to colored pigments but also to plate-shaped glitter pigments and paper surfaces, and as a result, colored pigments are easily adsorbed to plate-shaped glitter pigments and paper surfaces. It is suitable for ink compositions because it is easy to prevent the colored pigment from penetrating into the inside of the paper by adsorption, and the brilliance and color development of handwriting can be further improved.

The content of the water-dispersible polymer is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, based on the total mass of the ink composition. When the content is within the above range, the ink composition can be suppressed from excessively thickening, and the dispersion stability of the plate-shaped glitter pigments and colored pigments can be improved, and the blurring and discontinuity of handwriting can be suppressed. Easy to form handwriting with excellent color development.

The ink composition further contains a water-soluble copolymer of acrylic acid and a sulfonic acid monomer, so that the colored pigment permeates into the interior from the paper surface and the plate-like glitter pigment aggregates. This makes it easier to form handwriting with better color development and glitter while suppressing blurring and discontinuity of handwriting.
The copolymer is made water-soluble by neutralizing a copolymer of acrylic acid and a sulfonic acid monomer with an alkaline substance such as sodium hydroxide, ammonia, or alkanolamine, and is applied to an ink composition. Specific examples include neutralized copolymers of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, with trade names: Aron A-6012, Aron A-6016, Aron A- 6017 and A-6020 (sodium salt of a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, manufactured by Toagosei Co., Ltd.) can be used.
The copolymer of acrylic acid and sulfonic acid monomer that can be used in the ink composition is not limited to the above.
A plurality of types of the above copolymers can be used in combination.

The content of the copolymer of acrylic acid and sulfonic acid monomer is preferably 0.05 to 2% by mass, and preferably 0.1 to 1% by mass, based on the total mass of the ink composition. More preferred. When the content is within the above range, it is easy to form handwriting with excellent glitter and color development while suppressing excessive thickening of the ink composition and deterioration of ink ejection properties from the pen tip.

Further, in the water-based ink composition, when the total mass of the water-dispersible polymer is X and the total mass of the copolymer of acrylic acid and sulfonic acid monomer is Y, Y/X is 0. It is preferably 1 to 1.0, more preferably 0.2 to 0.8. Particularly preferably, it is 0.3 to 0.6. When the value of the ratio of the total mass is within the above range, it is possible to suppress the coloring pigment from penetrating into the inside from the paper surface and the aggregation of the plate-like glitter pigment, and to provide excellent color development and glitter of handwriting. Easy to form handwriting.

The coloring pigments include inorganic pigments such as carbon black and ultramarine, organic pigments such as copper phthalocyanine blue and benzidine yellow, and aqueous dispersions that have been stably finely dispersed in an aqueous medium using a surfactant or the like. Pigment products etc. are used, for example, C.I. I. Pigment Blue 15:3B [Product name: S. S. Blue GLL, pigment content 22%, manufactured by Sanyo Shiki Co., Ltd.], C.I. I. Pigment Red 146 [Product name: S. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Shiki Co., Ltd.], C.I. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content approximately 30%, manufactured by Dainichiseika Kagyo Co., Ltd.], C.I. I. Pigment Red 220/166 [Product name: TC Red FG, pigment content approximately 35%, manufactured by Dainichiseika Kagyo Co., Ltd.].
As the fluorescent pigment, fluorescent pigments in the form of synthetic resin fine particles in which various fluorescent dyes are made into a solid solution in a resin matrix can be used.
Other examples include luminescent pigments, white pigments such as titanium dioxide, thermochromic compositions, photochromic compositions, and capsule pigments obtained by directly or microencapsulating perfumes and the like.

The thermochromic composition is a reversible thermochromic composition comprising (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the coloring reaction of both of the above occurs. The pigment composition is preferably encapsulated in microcapsules and applied as a reversibly thermochromic microcapsule pigment.
The reversible thermochromic composition has a temperature that changes at a predetermined temperature (color change point) as described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc. It changes color before and after, exhibits a decolored state in a temperature range above the high temperature side discoloration point, and a colored state in a temperature range below the low temperature side discoloration point, and of the above two states, only one specific state exists in the normal temperature range, The other state is maintained as long as the heat or cold required to bring it about is applied, but when the heat or cold is no longer applied, it returns to the state it exhibits at room temperature, with a hysteresis width. A heat-decolorable microcapsule pigment in which a reversible thermochromic composition having relatively small characteristics (ΔH=1 to 7° C.) is encapsulated in microcapsules can be used.
Furthermore, relatively large hysteresis characteristics (ΔH=8 to 50 °C), or exhibit large hysteresis characteristics as described in JP-A No. 2006-137886, JP-A No. 2006-188660, JP-A No. 2008-45062, JP-A No. 2008-280523, etc. In other words, the shape of the curve plotting the change in coloring density due to temperature change is significantly different when the temperature is raised from a lower side than the discoloration temperature range and when it is lowered from a higher temperature side than the discoloration temperature range. A reversible thermochromic composition that changes color along a specific temperature range, and exhibits color development in a low temperature range below the complete color development temperature or discoloration state in a high temperature range above the complete color discoloration temperature, and has color memory in a specific temperature range. Microcapsule pigments that are color-erasable by heating can also be applied.
In addition, specifically, the reversible thermochromic composition having color memory properties is a temperature at which the complete color development temperature can only be obtained in a freezing room, a cold region, etc., that is, -50 to 0°C, preferably -40 to - 5°C, more preferably -30 to -10°C, and the complete discoloration temperature is the temperature obtained from frictional heat from a friction body or a familiar heating element such as a hair dryer, that is, 50 to 95°C, preferably 50 to 90°C. , more preferably in the range of 60 to 80°C, and by specifying the ΔH value in the range of 40 to 100°C, it can effectively function to maintain the color exhibited under normal conditions (daily living temperature range).

Furthermore, if necessary, a dye soluble in an aqueous medium can also be used in combination.
As the dye, acid dyes, basic dyes, direct dyes, etc. can be used, and examples of the acid dyes include New Coccin (C.I. 16255), Tartrazine (C.I. 19140), and Acid Blue Black. 10B (C.I.20470), Guinea Green (C.I.42085), Brilliant Blue FCF (C.I.42090), Acid Violet 6B (C.I.42640), Soluble Blue (C.I.42755) ), naphthalene green (C.I.44025), eosin (C.I.45380), phloxine (C.I.45410), erythrosine (C.I.45430), nigrosine (C.I.50420), acidflavin (C.I.56205) etc. are used.
Basic dyes include chrysoidine (C.I. 11270), methyl violet FN (C.I. 42535), crystal violet (C.I. 42555), malachite green (C.I. 42000), Victoria Blue FB ( C.I.44045), Rhodamine B (C.I.45170), Acridine Orange NS (C.I.46005), Methylene Blue B (C.I.52015), etc. are used.
Direct dyes include Congo Red (C.I.22120), Direct Sky Blue 5B (C.I.24400), Violet BB (C.I.27905), Direct Deep Black EX (C.I.30235), and Kaya. Russ Black G Conch (C.I. 35225), Direct Fast Black G (C.I. 35255), Phthalocyanine Blue (C.I. 74180), etc. are used.

The coloring pigments may be used alone or in a suitable mixture of two or more, and are preferably used in an amount of 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, in the ink composition.

In addition, considering that the handwriting should have good color development and glitter while suppressing blurring and breaks in the handwriting, the total mass of the coloring pigment and the total mass of the plate-like glitter pigment should be When the sum of the above is A and the total mass of the water-dispersible polymer is B, B/A is preferably 0.05 to 0.5, and preferably 0.1 to 0.4. More preferred.

Furthermore, a general-purpose pigment dispersant can also be used in the ink composition. As the pigment dispersant, water-soluble resins, surfactants, etc. can be used. Examples of the water-soluble resin include water-soluble maleic acid resin, water-soluble styrene resin, water-soluble styrene-maleic acid resin, polyvinylpyrrolidone, polyvinyl alcohol, and water-soluble urethane resin. Further, the surfactant may be arbitrarily selected from anionic, cationic, nonionic, and amphoteric surfactants.

A thickener is added to the ink composition. Thereby, it is possible to suppress sedimentation of particle components (plate-like bright pigments, colored pigments) and handwriting blurring during storage.
As the thickener, conventionally known ones can be used, but preferably a substance that can impart shear thinning properties to the ink composition (shear thinning properties imparting agent).
By using a shear thinning agent in the ink composition, it is possible to improve the anti-sedimentation stability of the particles and suppress the blurring of handwriting without impairing the ink discharge properties during writing.

As the shear thinning agent, substances that are soluble or dispersible in water are effective, such as xanthan gum, welan gum, succinoglycan (average molecular weight 1 million to 8 million), guar gum, locust bean gum and its derivatives, hydroxyethylcellulose, alginate alkyl esters, polymers with a molecular weight of 100,000 to 150,000 whose main component is an alkyl ester of methacrylic acid, glucomannan, agar, and carrageenan. Carbohydrates with gelling ability extracted from seaweeds such as benzylidene sorbitol and benzylidene xylitol or derivatives thereof, crosslinkable acrylic acid polymer, polyN-vinylcarboxylic acid amide, inorganic fine particles, nonions with an HLB value of 8 to 12. Examples include metal salts and amine salts of dialkyl sulfosuccinic acid, and even when N-alkyl-2-pyrrolidone and anionic surfactant are added in combination to the ink composition, they are stable. Can impart shear thinning properties.

The content of the thickener is preferably 0.01 to 3% by mass, more preferably 0.1 to 1% by mass, based on the total mass of the ink composition. When the content of the thickener is within the above range, it is easy to achieve both ink ejection properties during writing, anti-sedimentation stability of the pigment, and suppression of handwriting blurring.

A conventional general-purpose water-soluble organic solvent that is compatible with water is used in the water-based ink composition in order to prevent excessive evaporation of water from the ink contained in the refill and a decrease in ink discharge properties. Specifically, ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol mono Examples include ethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone and the like.
The water-soluble organic solvents may be used alone or in combination of two or more, and are preferably used in an amount of 1 to 20% by mass, more preferably 5 to 15% by mass.
When the content of the organic solvent is within the above range, it becomes easier to suppress excessive water evaporation without increasing the ink viscosity, thereby maintaining good ink ejection properties and producing unbroken handwriting for a long period of time. Easy to form.

In addition, the water content should be 40 to 80% by mass based on the total mass of the ink composition, in order to increase the fluidity of the ink composition and improve the ink ejection properties from the pen tip. is preferable, and more preferably 45 to 70% by mass.

Preferably, the ink composition contains a phosphate ester surfactant.
The phosphate ester surfactant also adsorbs to the surface of the ball and the surface of the ball seat of the ballpoint pen tip, forming a lubricating layer made of the phosphate ester surfactant on the ball surface and the surface of the ball seat. The ball can rotate more smoothly when writing.
Furthermore, the phosphate ester surfactant can also be adsorbed onto the surface of the pigment, thereby making it easier to suppress aggregation and sedimentation of the pigment.

式中、Ｘ_１、Ｘ_２、Ｘ_３は、下記式（２）に示す官能基、または水酸基であり、Ｘ_１、Ｘ_２、Ｘ_３の少なくとも１種は、式（２）に示す官能基である。

式中、Ｒ_１は炭化水素基、Ｒ_２はアルキレン基である。また、ｎは１以上の整数である。 The phosphate ester surfactant used in the ink composition is a compound represented by the following formula (1).

In the formula, X ₁ , X ₂ , and X ₃ are the functional groups shown in the following formula (2) or hydroxyl groups, and at least one of X ₁ , X ₂ , and X ₃ is the functional group shown in the formula (2). It is.

In the formula, R ₁ is a hydrocarbon group, and R ₂ is an alkylene group. Further, n is an integer of 1 or more.

A preferable phosphate ester surfactant for the ink composition is a phosphate ester surfactant in which the hydrocarbon group is an alkyl group, an alkenyl group, or an aryl group, and more preferably, the hydrocarbon group is an alkyl group. , an alkenyl group or an aryl group, and the alkylene group is an ethylene group. A particularly preferred phosphate ester surfactant is a phosphate ester surfactant in which the hydrocarbon group is an alkyl group and the alkylene group is an ethylene group, that is, polyoxyethylene alkyl ether phosphoric acid. By using the polyoxyethylene alkyl ether phosphoric acid, the rotation of the ball during writing becomes smoother, the ink ejectability during writing becomes even better, and it becomes easier to suppress aggregation and sedimentation of pigments. Can be done. This is due to the fact that the polyoxyethylene alkyl ether phosphoric acid has a high affinity not only for balls and ball chips but also for pigments. This is because it has an excellent effect on dispersibility. In particular, ballpoint pens that use the plate-like glitter pigments as the ink colorant may have difficulty achieving a smooth writing feel and good ink ejection properties, but polyoxyethylene alkyl ether phosphoric acid has plate-like glitter pigments. The pigment is interposed between the ball surface and the ball seat surface, and the pigment is adsorbed to the ball surface and the ball seat surface, so that the pigment has a roller effect when the ball rotates when writing, so the ball rotates smoothly. As a result, it is easy to improve the writing feel and ink ejection properties.
The phosphate ester surfactant may be an alkali metal salt or an amine salt.

The content of the phosphate ester surfactant is preferably 0.01 to 5% by mass, more preferably 0.1 to 3% by mass, based on the total mass of the ink composition. By setting the content of the phosphate ester surfactant in the ink composition within the above range, it is possible to improve the dissolution stability of the phosphate ester surfactant, facilitate smooth ball rotation, and improve pigment aggregation. , it becomes easy to suppress sedimentation.

Furthermore, a water-soluble resin may be added to the ink composition in order to impart adhesion to the paper surface and viscosity. Examples of the water-soluble resin include alkyd resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin. The water-soluble resins may be used alone or in combination of two or more, and are used in an amount of 1 to 30% by weight in the ink composition.

In addition, the ink composition may optionally include inorganic salts such as sodium carbonate, sodium phosphate, and sodium acetate, pH adjusters such as organic basic compounds such as water-soluble amine compounds, benzotriazole, tolyltriazole, Rust inhibitors such as 2,5-dimercapto-1,3,4-thiadiazole and saponin, carbolic acid, sodium salt of 1,2-benzthiazolin 3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, paraoxybenzoin Preservatives or fungicides such as propyl acid, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, urea, nonionic surfactants, sorbitol, mannitol, sucrose, glucose, reduced starch A hydrolyzate, a wetting agent such as sodium pyrophosphate, an antifoaming agent, and a fluorine-based surfactant or nonionic surfactant that improves ink permeability may be used.
Furthermore, ascorbic acids, erythorbic acids, α-tocopherol, catechins, synthetic polyphenols, kojic acid, alkylhydroxylamines, oxime derivatives, α-glucosylrutin, α-lipoic acid, phosphonates, phosphinates, sulfites, sulfoxyls. Air bubbles can also be chemically removed by adding acid salts, dithionites, thiosulfates, thiourea dioxide, and the like.
Furthermore, dextrin can also be used to increase the dry-up resistance of the pen tip.
In addition, oligomers of N-vinyl-2-pyrrolidone, oligomers of N-vinyl-2-piperidone, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, and N-vinyl-ε-caprolactam are also available. Addition of thickening inhibitors such as oligomers can also enhance functionality in the retractable form.
Furthermore, lubricants can be used, such as metal soaps, polyalkylene glycol fatty acid esters, ethylene oxide-added cationic surfactants, phosphate ester-based surfactants, β-alanine surfactants, N-acyl amino acids, N-acylmethyltaurine, 2,5-dimercapto-1,3,4-thiadiazole and its salts and oligomers, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate , α-lipoic acid, a condensate of N-acyl-L-glutamic acid and L-lysine, or a salt thereof.

It is important that the viscosity of the aqueous ink composition at 20° C. is 800 to 1600 mPa·s, preferably 1000 to 1500 mPa·s, at a shear rate of 3.84 sec ⁻¹ .
Note that the viscosity can be measured using, for example, a rheometer "DHR-2" manufactured by TA Instruments.

Furthermore, it is important that the shear thinning index n at 20°C of the aqueous ink composition is 0.15 to 0.5, preferably 0.2 to 0.4, and preferably 0.25 to 0.5. More preferably, it is 0.35. Here, the shear thinning index n refers to n in the viscosity equation represented by S=αD ⁿ . Note that S represents shear stress (dyn/cm ² =0.1 Pa), D represents shear rate (sec ⁻¹ ), and α represents viscosity coefficient.
The shear thinning index n can be measured using, for example, a rheometer "DHR-2" manufactured by TA Instruments, and the shear thinning index ⁿ can be measured using a rheometer "DHR- ^2" manufactured ^by TA Instruments. The shear rate and the shear stress obtained at each shear rate are applied to the above equation to find n.
When the viscosity and shear thinning index of the aqueous ink composition are within the above numerical ranges, the plate-like bright pigments and colored pigments are prevented from settling and aggregating when left still, while the ink from the pen tip during writing is suppressed. It has good ejection properties, and can form clear handwriting with excellent color development and brightness, with less fading and interruptions.

The surface tension of the aqueous ink composition is preferably 25 to 55 mN/m in a 20°C environment. When the surface tension is within the above-mentioned numerical range, it is possible to suppress blurring, discontinuity, blurring, etc. of handwriting, and improve writing properties. Taking into consideration the improvement of writability, the surface tension of the aqueous ink composition is more preferably 30 to 50 mN/m.
Note that the surface tension is determined by measuring in a 20° C. environment using a surface tension measuring device manufactured by Kyowa Interface Science Co., Ltd. and a vertical plate method using a platinum plate.

The pH of the aqueous ink composition is preferably 6 to 10, more preferably 7 to 9. If the pH of the aqueous ink composition is within the above numerical range, the dispersibility of the coloring material can be easily improved.
In the present invention, the pH value can be measured at 20° C. using, for example, a pH meter “D-51” manufactured by Horiba, Ltd.

The aqueous ink composition can be produced by any conventionally known method. Specifically, the above-mentioned components can be mixed in required amounts and mixed using various stirrers such as a propeller stirrer, homodisper, or homomixer, and various dispersion machines such as a bead mill.

The water-based ink composition includes water, a water-soluble organic solvent, a plate-like bright pigment, a colored pigment, and one or more kinds of acrylic acid-based polymers, urethane-based polymers, and olefin-based polymers having water dispersibility. Contains at least a water-dispersible polymer and a thickener, and has a viscosity and shear thinning index within a specific range, resulting in good dispersion stability and ink ejectability of plate-like bright pigments and color pigments. At the same time, the colored pigments are prevented from sinking from the paper surface into the interior of the paper, so it is possible to form vivid handwriting with excellent color development and glitter, with less fading and breakage.
The dispersion stability of pigments persists even after long periods of time or when the amount of water in the ink decreases over time and the concentrations of plate-like glitter pigments and color pigments increase. Even if the water content of the water-based ink composition decreases, excessive thickening is suppressed and good ink discharge properties are maintained, so that the water-based ink composition can form the above-mentioned vivid handwriting over a long period of time.

The ballpoint pen refill of the present invention incorporates the water-based ink composition in an ink storage tube attached to the ballpoint pen tip directly or via a holder, and has an ink backflow preventer that follows the ink as the ink is consumed. (liquid stopper).

The structure and shape of the pen tip (ballpoint pen tip) are not particularly limited. For example, there is a ball holding chamber for holding balls made by cutting metal with a drill or the like, an ink circulation hole formed in the center of the bottom wall of the ball holding chamber, and a hole extending radially from the ink circulation hole. By caulking the tip end of the chip body provided with a plurality of extending ink circulation grooves inward, a part of the ball held in the ball holding chamber is made to protrude from the tip edge of the tip, and the ball is The structure includes a rotatably held structure, and a caulking part formed by pressing and deforming the tapered tip of a metal pipe radially inward, and a side wall near the tip of the pipe radially inward. A so-called pipe-type ballpoint pen tip structure has a ball holding part in which a ball is rotatably held by a plurality of inwardly protruding parts formed by pressing and deforming the tip.

The pipe may be, for example, a cylindrical body with a straight tip (straight cylindrical body), and a shape in which the outer diameter and the inner diameter become larger at the rear of the tip. The shape of the pipe may be a straight cylindrical body as a whole.

Considering that the ink ejection properties from the ballpoint pen tip are good, the ballpoint pen tip is the pipe-type ballpoint pen tip, and the tip of the pipe is a straight cylindrical body, and the tip of the tip is a straight cylindrical body. A ballpoint pen tip (hereinafter sometimes referred to as a pipe-type ballpoint pen tip having a shape in which the rear end of the tip part increases in diameter) is preferable.

The pipe-type ballpoint pen tip has a shape in which the diameter expands at the rear of the tip, and the ink flow path behind the ball holding chamber inside the ballpoint pen tip is formed wide, allowing ample ink to flow into the ball holding chamber. Can be supplied. A ballpoint pen refill equipped with such a ballpoint pen tip has good ink ejection properties from the pen tip, has excellent brightness and color development, and is easy to form clear handwriting with less blurring and blurring.

The materials of the ballpoint pen tip and the ball held in the ballpoint pen tip are stainless steel, tungsten carbide-based cemented carbide, silicon carbide, alumina, and zirconia, in consideration of good wear resistance of the ball and ball seat. , silicon nitride, etc., and is preferably used.

The ball diameter is preferably 0.2 to 0.7 mm, preferably 0.3 to 0.5 mm, and more preferably 0.3 to 0.45 mm.

Ballpoint pen refills with a ball diameter of 0.7 mm or less, particularly less than 0.5 mm, have a small amount of ink discharged, and it may be difficult to obtain good handwriting clarity. However, the above-mentioned pipe-type ballpoint pen tip, which has a shape where the diameter expands at the rear of the tip, has good ink ejection performance even when equipped with a ball having such an outer diameter, and produces clear ink with suppressed fading and interruptions. In order to facilitate the formation of handwriting, it can be preferably used in combination with a ball having a ball diameter within the above range.

The ballpoint pen tip may include a springing member within the tip that springs the rear end of the ball forward. As a result, when writing, the ball can be pushed back by the pressure of the pen to allow ink to flow out, and when not writing, the ball is pressed against the inner edge of the tip to create a close contact, thereby suppressing ink leakage when not in use. This makes it easier.

Examples of the elastic member include a spring made of thin metal wire, a spring made of thin metal wire with a straight part (rod part) at one end, a linear plastic processed body, etc.
It is configured to be able to be pressed with an elastic force of 10 g or more and 40 g or less.

The ink storage tube to which the ballpoint pen tip is attached directly or via a holder is made of a synthetic resin molded member such as polyethylene, polypropylene, polyethylene terephthalate, or ethylene vinyl acetate copolymer resin, which has low water vapor permeability and productivity. It is used because it has good transparency and excellent visibility of the filled ink.
Examples of the polyethylene include low-density polyethylene, linear short-chain branched polyethylene, metallocene-catalyzed linear short-chain branched polyethylene, and high-density polyethylene, and examples of the polypropylene include homopolymer polypropylene, random copolymer polypropylene, and block copolymer. Polypropylene can be mentioned, and any of them can be preferably used. Among these, polypropylene is preferably used because it has excellent strength and heat resistance, low moisture permeability, and tends to suppress ink thickening due to moisture evaporation over time.
The ink storage tube is obtained by extrusion molding or injection molding the synthetic resin.
Further, the surface of the resin may be coated with another material.

The ink storage tube made of the synthetic resin may have a single layer or a multilayer structure, but in order to prevent ink from deteriorating over time, the ink storage tube has a multilayer structure and is injected with a gas such as oxygen. It is preferable to have a layer that prevents permeation. Furthermore, in order to prevent ink from adhering to the inner wall of the ink storage tube, if necessary, the inner surface of the ink storage tube may be coated with silicone resin, fluororesin, or the like for ink-repellent treatment.

The ink storage tube has an outer diameter of 2.5 to 4 mm and a wall thickness of 0.3 to 1 mm.
An ink storage tube whose outer diameter and wall thickness are within the above ranges is slender and can have both a sufficient amount of ink and high strength, so a ballpoint pen refill equipped with the ink storage tube is When housed in a compound type retractable ballpoint pen in which a plurality of ballpoint pen refills are housed in a barrel, and the writing tip of one of the ballpoint pen refills protrudes and retracts from the front end opening of the barrel by the operation of a retracting mechanism, the ballpoint pen It is possible to make a highly practical ballpoint pen that can write at a sufficient distance while having a slim outer diameter of the barrel.
Ballpoint pen refills equipped with the ink storage tube are prone to water from the built-in ink passing through the ink storage tube and volatilizing out of the refill over time, resulting in solid content agglomeration and ink overflow due to a decrease in water content. Ink dischargeability tends to decrease due to increased viscosity. This tendency is particularly noticeable when the ink in the ballpoint pen refill contains a large amount of solid content such as pigments, such as plate-shaped glitter pigment ink, and the ink dischargeability tends to deteriorate. However, although the ink composition is an ink using a plate-like bright pigment, it is possible to suppress excessive thickening of the ink viscosity even after a long period of time or when the water content in the composition decreases over time. Since good dispersibility of the plate-shaped bright pigment and colored pigment is maintained, the ballpoint pen refill of the present invention containing the ink composition maintains good ink ejection properties even though it is equipped with the ink storage tube. , it is possible to stably form handwriting that is excellent in glitter and coloring properties of colored pigments over a long period of time.
In addition, since the ballpoint pen refill equipped with the ink storage tube is not easily deformed when an impact is applied to the liquid stopper, ink can be prevented from leaking from the rear end of the refill when the ballpoint pen refill is dropped. can. Therefore, the ballpoint pen refill has excellent storage properties.
The outer diameter of the ink storage tube is preferably 2.5 to 3.5 mm, and the wall thickness is preferably 0.5 to 0.8 mm.

Further, an ink backflow preventer (liquid plug) is disposed at the rear end of the ink composition filled in the ink storage tube.
The ink backflow preventer is a viscous liquid that uses a nonvolatile medium as a base oil and has a high viscosity by adding solids such as silica, aluminum silicate, swellable mica, and fatty acid amide.
Non-volatile media used for the base oil include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, oligomer or cooligomer of α-olefin, dimethyl silicone oil, methylphenyl silicone oil. , amino-modified silicone oil, polyether-modified silicone oil, fatty acid-modified silicone oil, etc. When the solid is added, the viscosity tends to increase, the solid is difficult to separate over time, and water vapor permeation is difficult. Polybutene is preferably used because it has low viscosity and can easily suppress ink thickening over time due to moisture evaporation. The polybutene preferably has a kinematic viscosity of 1000 to 10000 mm ² s ⁻¹ at 40° C., more preferably 1500 to 5000 mm ² s ⁻¹ , even more preferably 2000 to 4000 mm ² s ⁻¹ . By using such polybutene as the base oil for the liquid stopper, the liquid stopper can easily follow the ink when ink is ejected during writing, making it easier to prevent ink ejection from being obstructed, and making it easier for ballpoint pen refills. Even if the ink composition drops and the load of the ink composition is applied to the liquid stopper, the liquid stopper is deformed and the ink leaks from the rear end of the refill.
The ink backflow preventer can be prepared by kneading the polybutene and the silica, aluminum silicate, swellable mica, fatty acid amide, etc. in a kneader such as a three-roll or kneader.
Further, the kinematic viscosity can be measured according to JIS K 2283:2000 "Crude oil and petroleum products - Kinematic viscosity test method and viscosity index calculation method".

Note that the ballpoint pen refill can be provided with a solid stopper together with the ink backflow preventer to suppress ink backflow.
Examples of the solid stopper include solid stoppers made of resin, such as polyethylene, polypropylene, and polymethylpentene.

The ballpoint pen refill of the present invention is attached to a retractable ballpoint pen, which is equipped with a retractable mechanism such as a cap type, a knock type, a rotary type, or a slide type, and is configured such that the pen tip can be retracted and retracted from the tip hole of the barrel.

When applying a retractable type ballpoint pen, the structure and shape of the retractable type ballpoint pen are not particularly limited. Any structure in which the writing tip protrudes from the barrel opening due to the operation of the protruding/retracting mechanism can be used. Examples of operating methods for the retracting mechanism include a knocking type, a rotating type, and a sliding type. The knock type has a knock part on the rear end of the barrel or the side of the barrel, and the writing tip part is moved out and out of the front end opening of the barrel by pressing the knock part, or a clip part provided on the barrel is used. An example of a configuration can be illustrated in which the writing tip part is moved out and out of the front end opening of the barrel by pressing. An example of the rotary type is a configuration in which a rotating part is provided at the rear of the barrel, and by rotating the rotating part, the writing tip part is moved in and out of the front end opening of the barrel. The sliding type has a sliding part on the side of the barrel, and by operating the slide, the writing tip can be moved out and out of the front end opening of the barrel, or by sliding the clip part provided on the barrel, An example of this configuration is a configuration in which the tip portion protrudes and retracts from the front end opening of the barrel. A retractable ballpoint pen is a composite type retractable ballpoint pen (hereinafter referred to as a composite type retractable ballpoint pen) in which multiple ballpoint pen refills are housed in a barrel, and the writing tip of one of the ballpoint pen refills retracts from the front end opening of the barrel by the operation of the retractable mechanism. (sometimes referred to as a type of retractable ballpoint pen).
Furthermore, by using a transparent, colored transparent, or semi-transparent molded body as the barrel, it is possible to check the ink color, the amount of ink remaining, etc.

Although the ballpoint pen refill of the present invention is slender, it has excellent brightness and color development, and can form vivid handwriting without blurring or interruption over a long period of time, so it is a composite type that is suitable for a slender ballpoint pen refill. It can be preferably used for a retractable ballpoint pen.

An example of a ballpoint pen refill according to this embodiment will be described below with reference to the drawings.

- Ballpoint Pen Refill Embodiments of the ballpoint pen refill are shown in FIGS. 1 to 3.
The ballpoint pen refill 1 of this embodiment includes a ballpoint pen tip 2 rotatably holding a ball 4 at the front end, a spring 5 housed inside the ballpoint pen tip 2, and a ballpoint pen tip 2 at the front end. It includes a holder 6 which is press-fitted and fixed, and an ink storage tube 7 whose rear part is press-fitted and fixed to the front end opening of the holder.
In this embodiment, "front" refers to the pen tip ball side, and "rear" refers to the opposite side.

- Ballpoint Pen Tip The ballpoint pen tip 2 consists of a tip body 3 and a ball 4. The tip body 3 includes a right cylindrical small-diameter cylindrical portion 31 that rotatably holds the ball 4 at its front end, and a taper that is integrally connected to the rear of the small-diameter cylindrical portion 31 and gradually increases in diameter toward the rear. It is made of a metal cylindrical body consisting of a cylindrical portion 32 and a right cylindrical large-diameter cylindrical portion 33 that is integrally connected to the rear of the tapered cylindrical portion 32 . The metal cylinder is made of, for example, austenitic stainless steel such as SUS304, SUS305, and SUS321.

A plurality (for example, four) of inward protrusions 31b are formed at equal intervals in the circumferential direction on the inner surface near the front end of the small-diameter cylindrical portion 31 of the tip body 3 by inward pressing deformation. The inward protrusion 31b forms a ball receiving seat. Further, the front end of the chip body 3 is pressed and deformed circumferentially inward to form an inward front end edge 31a. A ball holding portion for rotatably holding the ball 4 is formed between the front surface of the inwardly protruding portion 31b (ball receiving seat) and the rear surface of the front edge portion 31a. Ink flow holes 31c are formed between the inward protrusions 31b, extending radially outward from the center and penetrating in the axial direction. That is, the ink flow hole 31c is formed in the ball receiving seat. The ballpoint pen tip 2 may be of a type in which a ball receiving seat is formed at the front end of a metal tip body 3 by cutting.

-Right cylindrical inner surface A right cylindrical inner surface is formed on the inner surface of the small diameter cylindrical portion 31 rearward from the inward protruding portion 31b. A right cylindrical inner surface is formed on the inner surface of the large diameter cylindrical portion 33 .

-Tapered inner surface A tapered inner surface (or conical inner surface) whose diameter gradually increases toward the rear is formed on the inner surface of the tapered cylindrical portion 32.

- Spring In the spring 5, a front rod portion 51 and a rear coil portion 52 are integrally connected by one metal wire (for example, a stainless steel wire with a wire diameter of 0.11 mm).

- Rod Portion The rod portion 51 extends linearly in the axial direction and is inserted into the ink flow hole 31c of the ball receiving seat 31b. The front end of the rod portion 51 is brought into contact with substantially the center of the rear surface of the ball 4, and the rod portion 51 directly urges the ball 4 forward. Thereby, the ball 4 is brought into close contact with the inner circumferential surface of the front edge portion 31a, and leakage of ink from the front end of the tip body 3 and evaporation of ink can be prevented.

- Coil part The coil part 52 is formed by winding a wire material in a spiral shape. At the front end and the rear end of the coil part 52, a tightly wound part in which the wire rods are brought into close contact with each other is formed. An effective winding portion with a gap between the wire rods is formed in the intermediate portion of the coil portion 52 excluding the front end and the rear end. The elastic force with which the spring 5 urges the ball 4 forward (specifically, the load when pressing the ball 4 backward by 0.01 mm) is 14 grams to 25 grams (preferably 15 grams to 22 grams). The range is set to .

-Holder The holder 6 is a cylindrical body obtained by injection molding of synthetic resin (for example, polypropylene). The holder 6 includes a tapered front part 61 to which the ballpoint pen tip 1 is attached, a collar part 62 that comes into contact with the front end surface of the ink storage tube 7, and a rear part 63 that is press-fitted into the front end opening of the ink storage tube 7. Become. The rear part of the chip body 3 is press-fitted into the mounting hole of the front part 61 of the holder 6. A step portion 64 is protruded from the rear end of the inner surface of the mounting hole, and the rear end of the chip body 3 is locked to the step portion 64, and the rear end of the spring 5 (the rear end of the coil portion 52) is secured to the step portion 64. end) is locked.

- Ink storage tube The ink storage tube 7 is a cylindrical body with both ends open, obtained by extrusion molding of a synthetic resin (for example, polypropylene). The ink storage tube 7 has an outer diameter of 2.5 to 4 mm and a wall thickness of 0.3 to 1 mm, and contains ink 71 and a high viscosity fluid that advances as the ink 71 is consumed. An ink backflow preventer 72 consisting of the following is filled. The ink 71 is an aqueous ink composition related to the ballpoint pen refill of the present invention. The ink backflow preventer 72 may be a high viscosity fluid made by mixing a solid substance with polybutene as a base oil having a kinematic viscosity of 1000 to 10000 mm ² s ^-1 at 40°C.

- Ball The ball 4 used has a diameter A in the range of 0.2 mm to 0.7 mm (preferably 0.3 mm to 0.5 mm, more preferably 0.3 mm to 0.45 mm). Specifically, the ball 4 is prepared in a plurality of sizes depending on the desired width of handwriting, for example, the diameter is 0.2 mm, 0.25 mm, 0.3 mm, 0.4 mm, 0.5 mm, A 0.7mm one is adopted.

The movable amount of the ball 4 in the axial direction of the ball holding portion is preferably in the range of 0.02 mm to 0.05 mm from the viewpoint of obtaining smooth ink flow. The movable amount of the ball 4 in the axial direction of the ball holding part varies depending on the diameter A of the ball 4, and is set in the range of 5% to 15% (preferably 8% to 12%) of the diameter A of the ball 4, This provides smooth ink flow and sufficient ball exposure.

The ball 4 may be made of stainless steel, cemented carbide based on tungsten carbide, silicon carbide, alumina, zirconia, silicon nitride, or the like.
The axially forward exposure amount E of the ball 4 is set in a range of 22% to 32% of the diameter A of the ball 4. The amount E of the ball 4 exposed forward in the axial direction is determined when the ball 4 is pressed backward against the forward bias of the spring and the ball 4 is in contact with each inward protrusion 31b (ball receiving seat). It is measured in When the diameter A is in the above range (particularly when the diameter A of the ball 4 is 0.3 mm to 0.45 mm), a common spring 6 is used when multiple types of balls 4 with different diameters are used to obtain multiple types of ballpoint pen tips 2. be done.

・Small diameter cylindrical portion When the diameter A of the ball 4 is within the above range (in particular, the diameter A of the ball 4 is 0.3 mm to 0.45 mm), the inner diameter B of the right cylindrical inner surface of the small diameter cylindrical portion 31 is equal to the diameter A of the ball 4. It is set larger than the diameter A. Specifically, the inner diameter B of the small diameter cylindrical portion 31 is set larger than the diameter A of the ball 4 by 0.03 mm to 0.06 mm.

The length F in the axial direction of the right cylindrical inner surface rearward of the inwardly protruding portion of the small diameter cylindrical portion 31 is set to be smaller than the diameter A of the ball 4. As a result, ink is abundantly supplied to the rear surface of the ball 4, and smooth ink flow is achieved.

・Tapered cylinder part When the diameter A of the ball 4 is within the above range (in particular, the diameter A of the ball 5 is 0.3 mm to 0.45 mm), the angle α (centered on the axis) of the tapered inner surface of the tapered cylinder part 32 is The angle α) of the conical inner surface is set to 30 degrees to 40 degrees. The length G in the axial direction of the tapered inner surface is set to be larger than the diameter A of the ball 4. Specifically, the axial length G of the tapered inner surface is set to 1.1 to 5.0 times (preferably 2 to 4.5 times) the diameter A of the ball 4. The tapered cylindrical portion 32 properly connects the small diameter cylindrical portion 31 and the large diameter cylindrical portion 33 so that smooth ink flow can be obtained.

・Large diameter cylindrical portion When the diameter A of the ball 4 is within the above range (in particular, the diameter A of the ball 4 is 0.3 mm to 0.45 mm), the inner diameter C of the right cylindrical inner surface of the large diameter cylindrical portion 33 is 0. .9 mm or more (preferably 1 mm or more), and the outer diameter D of the right cylindrical inner surface of the large diameter cylinder portion 33 is set to 1.2 mm or more (preferably 1.3 mm or more). The axial length H of the right cylindrical inner surface of the large-diameter cylindrical portion 333 is set in a range of 4.0 mm to 5.0 mm.

In addition, when the diameter A of the ball 4 is in the above range (particularly the diameter A of the ball 4 is 0.3 mm to 0.45 mm), if multiple types of balls 4 with different diameters are employed to obtain multiple types of ballpoint pen tips 1, each The inner diameters C of the large diameter cylindrical parts 33 are set to be the same, and the outer diameters D of each of the large diameter cylindrical parts 33 are set to be the same, so that the shape of the attachment part of the ballpoint pen tip 2 to the holder 6 is common. This makes it possible to simplify the manufacturing process.

-Summary The ballpoint pen refill 1 of this embodiment requires at least the following configuration.
The ballpoint pen refill 1 of this embodiment includes a ballpoint pen tip 2 that rotatably holds a ball 4 at its front end, a spring 5 housed inside the ballpoint pen tip 2, and a rear portion 63 of the ballpoint pen tip 2 fixed to each other. holder 6, and an ink storage tube 7 having a rear part 63 fixed to the front end opening of the holder 6,
The ink storage tube 7 is made of synthetic resin,
The ink storage tube 7 has an outer diameter of 2.5 to 4 mm and a wall thickness of 0.3 to 1 mm,
The inside of the ink storage tube 7 is filled with ink 71 and an ink backflow preventer 72 made of a high viscosity fluid that advances as the ink 71 is consumed.
The ballpoint pen tip 2 includes a right cylindrical small-diameter cylindrical portion 31 having a ball 4 rotatably held at its front end, and a taper that is integrally connected to the rear of the small-diameter cylindrical portion 31 and gradually increases in diameter toward the rear. The chip body 3 is made of a metal cylinder and includes a cylinder part 32 and a large diameter cylinder part 33 in the form of a right cylinder which is integrally connected to the rear of the tapered cylinder part 32,
The elastic force of the spring 5 that urges the ball 4 forward is set in the range of 14 g to 25 g,
The diameter A of the ball 4 is set in the range of 0.2 mm to 0.7 mm,
The movable amount of the ball 4 in the axial direction of the ball holding part is set in the range of 0.02 mm to 0.05 mm,
The inner diameter B of the right cylindrical inner surface of the small diameter cylindrical portion 31 behind the ball receiving seat 31b is set to be larger than the diameter A of the ball 4 by 0.03 mm to 0.06 mm,
The axial length F of the right cylindrical inner surface of the small diameter cylindrical portion 31 behind the ball receiving seat 31b is set smaller than the diameter A of the ball 4,
The inner diameter C of the right cylindrical inner surface of the large diameter cylindrical portion 33 is set to 0.9 mm or more.

Examples will be described below, but the present invention is not limited to these examples.
The table below shows the compositions of the glitter inks for ballpoint pen refills of Examples and Comparative Examples. Note that the composition values in the table indicate parts by mass.
Further, the average particle diameter is a value measured using a laser particle size distribution analyzer LA-300 (volume basis) manufactured by Horiba, and the median diameter is taken as the average particle diameter. At this time, the particle diameter of the plate-like bright pigment is calculated based on the assumption that the minimum value of the particle diameter axis in the particle size distribution diagram is 0.5 μm.

The contents of the raw materials in the table are explained according to the note numbers.
(1) Aluminum powder paste, manufactured by Toyo Aluminum Co., Ltd., product name: Alpaste WXM-0630 (aluminum powder content: 60% by mass, average particle size: 7 μm)
(2) Aluminum powder paste, manufactured by Toyo Aluminum Co., Ltd., product name: Alpaste EMERAL EMR-D5660H (aluminum powder content: 60% by mass, average particle size: 9 μm)
(3) Pearl pigment, manufactured by Merck Japan, trade name: Iriodin 221 (average particle size: 15 μm)
(4) Blue pigment aqueous dispersion with an average particle size of 0.2 μm (solid content: 20% by mass)
(5) Magenta pigment dispersion with an average particle size of 0.2 μm (solid content: 20% by mass)
(6) Yellow pigment dispersion with an average particle size of 0.2 μm (solid content: 16% by mass)
(7) Manufactured by Hodogaya Chemical Co., Ltd., trade name: Phloxine (8) Olefin polymer emulsion [water dispersion, manufactured by Sumitomo Seika Co., Ltd., trade name: Zaixen L, active ingredient: 25% by mass]
(9) Urethane polymer emulsion [water dispersion, manufactured by Kusumoto Kasei Co., Ltd., trade name: NeoRez R-2170, active ingredient: 40% by mass]
(10) Acrylic acid polymer emulsion [aqueous dispersion, manufactured by Kusumoto Kasei Co., Ltd., trade name: NeoCryl A-639, active ingredient: 42% by mass]
(11) Acrylic acid polymer emulsion [manufactured by Kusumoto Kasei Co., Ltd., trade name: NeoCryl A-6016, active ingredient: 45% by mass]
(12) Aqueous solution of sodium salt of copolymer of acrylic acid and sulfonic acid monomer [manufactured by Toagosei Co., Ltd., trade name: Aron A-6017 (solid content: 40% by mass)]
(13) Polyoxyethylene alkyl ether phosphoric acid [manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: PRICERF M208F]
(14) Succinoglycan (15) Dextrin [manufactured by Sanwa Starch Industries Co., Ltd., product name: Sandek #100]

Preparation of ink Each component was added to water and stirred at 20° C. at 2000 rpm using a disper for 1 hour, then a shear thinning agent was added and stirred for another 1 hour to prepare each ink.

Preparation of ink backflow preventer 1.5 parts of fatty acid amide as a thickener was added to 98.5 parts of polybutene as a base oil, and the mixture was kneaded with three rolls to obtain an ink backflow preventer.

Production of ballpoint pen refills Ballpoint pen refills according to the embodiments were produced using the ink compositions of the Examples and Comparative Examples. The ink storage tube was made of polypropylene resin, and had an outer diameter of 3.07 mm and a wall thickness of 0.69 mm.
The ball diameter was 0.4 mm, and the amount of ink contained in the ballpoint pen was 0.15 g.
The ink backflow preventer (liquid stopper) was prepared by kneading 98.5 parts of polybutene and 1.5 parts of fatty acid amide using three rolls.

Production of a ballpoint pen The ballpoint pen refill was attached to the exterior (product number: LHKC15C-NC, manufactured by Pilot Corporation) for the product name: HI-TEC-C COLETO [manufactured by Pilot Corporation], and a ballpoint pen was produced. .

The following tests were conducted using the ballpoint pen manufactured in the above-mentioned ballpoint pen manufacturing process.
・Evaluation of blurred and broken handwriting Using a ballpoint pen that was confirmed to be able to write, 20 spiral circles were continuously written on JIS P3201 writing paper A using an automatic writing tester to check the condition of the handwriting ( (Tested 10 pieces each). The test machine was used under the conditions of a writing load of 100 g, a writing angle of 70°, and a writing speed of 4 m/min.
〇...Able to form good handwriting without smudges or breaks.
△...Slight fading and interruptions are observed.
×: Fading and discontinuity are noticeable.
-Evaluation of brilliance and color development of handwriting Handwriting of 10 consecutive spiral circles handwritten on black paper was visually confirmed, and the brilliance and hue were sensory evaluated.
◎...The metallic shine and hue are clear.
〇…The metallic shine is clear and the hue is visible.
△...Although the metallic shine is clear, the hue is slightly difficult to see.
×...Although the metallic shine is clear, the hue is unclear.
-Evaluation of storage stability The ballpoint pen, which was confirmed to be able to write, was left in a constant temperature bath at 50° C. for 30 days, and then a spiral continuous circle was written by hand, and the handwriting was visually confirmed. Note that the writing paper was the above-mentioned writing paper A, and the writing load, writing angle, and writing speed were the same conditions as in the above-mentioned writing test.
〇…Similar to the initial stage, no blurring or breaks in handwriting are observed.
△...Compared to the initial stage, it is easier to visually recognize handwriting blurring and interruptions, but there is no problem in practical use.
×...It is impossible to write. Or, handwriting is noticeably blurred or broken compared to the initial stage.
The results of each of the above tests are shown in the table below.

(Application example)
Preparation of multicolor ballpoint pen Each ballpoint pen refill containing the ink compositions of Examples 5, 6, and 10 was used as an exterior package for the product name: HI-TEC-C COLETO [manufactured by Pilot Corporation] (product number: LHKC15C-NC). (manufactured by Pilot Corporation) to create a composite type retractable ballpoint pen (sliding type).
The ballpoint pen allows for easy attachment/detachment and sliding operations of each ballpoint pen refill, and forms handwriting with excellent shine over a long period of time without blurring or interruption and with vivid hues of red, blue, and yellow. I was able to do that.

Symbols of ballpoint pen refills shown in Figures 1 to 3 1 Ballpoint pen refill 2 Ballpoint pen tip (pen tip)
3 Chip body 31 Small diameter cylinder part 31a Front edge part 31b Inward protrusion part 31c Ink flow hole 32 Taper cylinder part 33 Large diameter cylinder part 4 Ball 5 Spring 51 Rod part 52 Coil part 6 Holder 61 Front part 62 Flange part 63 Rear part 64 Stepped portion 7 Ink storage tube 71 Ink 72 Ink backflow prevention body (liquid plug)
A Diameter of ball 4 B Inner diameter of right cylindrical inner surface of small diameter cylindrical portion 31 C Inner diameter of large diameter cylindrical portion 33 D Outer diameter of large diameter cylindrical portion 33 E Amount of ball 4 exposed forward in the axial direction F Small diameter cylindrical portion 31 The axial length of the right cylindrical inner surface behind the inwardly protruding part G The axial length of the tapered inner surface of the tapered cylindrical portion 32 H The axial length of the right cylindrical inner surface of the large diameter cylindrical portion 33

Claims (5)

A ballpoint pen refill comprising a pen nib and an ink storage tube, wherein the ink storage tube stores an aqueous ink composition, and an end surface of the aqueous ink composition is filled with an ink backflow preventer,
The pen point includes a caulked portion formed by radially inward pressing deformation on a tapered tip of a metal pipe, and a radially inward pressing deformation formed on a side wall near the tip of the pipe. A pipe-type ballpoint pen tip having a plurality of inward protrusions, and a ball holding part in which a ball is rotatably held by the caulking part and the plurality of inward protrusions,
The ballpoint pen tip includes: a right cylindrical small-diameter tube portion rotatably holding a ball at its front end; a tapered tube portion that is integrally connected to the rear of the small-diameter tube portion and whose diameter gradually increases toward the rear; Consisting of a metal cylindrical body consisting of a right cylindrical large-diameter cylindrical part integrally connected to the rear of the tapered cylindrical part,
The axial length of the right cylindrical inner surface rearward of the inwardly protruding portion of the small diameter cylindrical portion is smaller than the diameter of the ball;
The diameter of the ball is 0.3 to 0.5 mm,
The water-based ink composition contains water, a water-soluble organic solvent, a plate-like bright pigment, a colored pigment, and a water-dispersible acrylic acid polymer, a urethane polymer, and an olefin polymer selected from one or more water-dispersible polymers and a thickener;
The viscosity of the aqueous ink composition at 20 ° C. is 800 to 1600 mPa s at 3.84 sec-1,
The aqueous ink composition has a shear thinning index n of 0.15 to 0.5 at 20°C,
A ballpoint pen refill, wherein the ink storage tube is made of synthetic resin and has an outer diameter of 2.5 to 4.0 mm and a wall thickness of 0.3 to 1.0 mm. The ballpoint pen refill according to claim 1, wherein the inner diameter of the right cylindrical inner surface of the small diameter cylindrical portion is 0.03 to 0.06 mm larger than the diameter of the ball. The ballpoint pen refill according to claim 1 or 2, wherein the inner diameter of the right cylindrical inner surface of the large diameter cylinder portion is 0.9 mm or more. A ballpoint pen containing the ballpoint pen refill according to any one of claims 1 to 3. According to claim 4, the retractable ballpoint pen is a composite type in which a plurality of ballpoint pen refills are housed in a barrel, and the writing tip of any one of the ballpoint pen refills comes out and retracts from the front end opening of the barrel by actuation of a retracting mechanism. Ballpoint pen listed.

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