JP2022171311A - Aqueous ink composition for ball point pen and aqueous ball point pen storing the same - Google Patents

Abstract

To provide an aqueous ink composition applied for a ball point pen having a metal ball, being excellent in initial writing performance, capable of forming a preferable handwriting without writing failure such as, blur and line omission in starting of writing, even being preserved for a long term, and exhibiting a smooth writing feeling, and a ball point pen storing the same.SOLUTION: There is provided an aqueous ink composition which is stored in a ball point pen, the ball point pen comprises a ball point pen tip formed of: a tip main body; and a metal ball provided on a front end of the tip main body. The ball point pen aqueous ink composition is formed of at least: a dye stuff; a specific benzotriazole based compound; a specific naphthalene disulfonic compound and/or a salt thereof; and water. There is also provided an aqueous ball point pen storing the same.SELECTED DRAWING: None

Description

The present invention relates to a water-based ink composition for ball-point pens and water-based ball-point pens containing the same. More specifically, even after being stored for a long period of time, it is possible to form good handwriting without causing writing defects such as faint lines and line skipping at the time of writing, and the writing feeling is smooth. It relates to an ink composition and a water-based ball-point pen containing the same.

Conventionally, inks containing water as a main solvent (water-based inks) have been known and widely used due to their low odor and high safety. Water-based ink is sometimes used in writing instruments such as ballpoint pens, and writing instruments containing water-based ink are required not to cause writing defects such as faint lines and line skipping when writing. Therefore, studies have been conducted to suppress poor writing at the time of writing (see Patent Document 1, for example).
Patent Document 1 describes an ink composition for water-based ballpoint pens containing a colorant, a water-soluble organic solvent, water, a specific neutral polysaccharide, and one or two of dimethylformamide and dimethylsulfoxide. is disclosed.
The above ink composition has excellent ink flowability at the time of writing, that is, excellent initial writing performance. The performance was insufficient, and in particular, when the pen was stored for a long period of time with the writing tip pointing upward, writing defects tended to occur.

JP-A-6-145581

The present invention provides a water-based ink composition to be applied to a ball-point pen having a metal ball, which has excellent initial writing performance, and even after being stored for a long period of time, writing such as blurring and line skipping occurs at the time of writing. To provide a water-based ink composition for a ball-point pen capable of forming good handwriting without causing defects and exhibiting a smooth writing feeling, and to provide a water-based ball-point pen containing the same.

（式中、Ｘは、水素原子、炭素数１～４のアルキル基、カルボキシ基、又はニトロ基である）

〔式中、Ｙ_１及びＹ_２は、それぞれ独立に、水素原子、ヒドロキシ基、炭素数１～４のアルキル基、炭素数１～３のアルコキシ基、アミノ基、又は炭素数１～４のアルキル置換アミノ基である（但し、Ｙ_１及びＹ_２が共に、水素原子である場合は除く）〕
また、前記インキ組成物の総質量に対する、前記式（１）で示される化合物の含有率をＰ_１とするとき、前記Ｐ_１が０．１～３質量％であること、前記インキ組成物の総質量に対する、前記式（２）で示される化合物及び／又はその塩の含有率をＰ_２とするとき、前記Ｐ_２が０．１～３質量％であること、前記Ｐ_１及びＰ_２に関して、０．５≦Ｐ_２／Ｐ_１≦５を満たすこと、前記式（１）におけるＸが、水素原子又はメチル基であり、且つ、前記式（２）におけるＹ_１及びＹ_２が、それぞれ独立に、水素原子、ヒドロキシ基、又はアミノ基である（但し、Ｙ_１及びＹ_２が共に、水素原子である場合は除く）ことを要件とする。
さらには、前記インキ組成物を収容してなり、且つ、ペン先として、チップ本体と、前記チップ本体の前端に備えられる金属製のボールとからなるボールペンチップを備えてなる水性ボールペン、前記ボールペンが、軸筒内に繊維集束体からなるインキ吸蔵体を内蔵し、前記インキ吸蔵体に前記インキ組成物が含侵されてなり、且つ、前記インキ吸蔵体から前記ボールペンチップへインキを誘導するためのインキ誘導芯を備えてなる中詰式ボールペンであること、前記チップ本体が合成樹脂からなり、且つ、ボール受け座が前記チップ本体の内部に一体に形成されてなることを要件とする。 The present invention provides an aqueous ink composition contained in a ball-point pen comprising, as a nib, a ball-point pen tip consisting of a tip body and a metal ball provided at the front end of the tip body, comprising at least a dye, A water-based ink composition for ballpoint pens comprising a compound represented by the following formula (1), a compound represented by the following formula (2) and/or a salt thereof, and water is required.

(Wherein, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a carboxy group, or a nitro group)

[In the formula, Y ₁ and Y ₂ are each independently a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an amino group, or an alkyl group having 1 to 4 carbon atoms. a substituted amino group (except when both Y ₁ and Y ₂ are hydrogen atoms)]
Further, when P ₁ is the content of the compound represented by the formula (1) with respect to the total mass of the ink composition, the P ₁ is 0.1 to 3% by mass. When the content of the compound represented by the formula (2) and/or a salt thereof with respect to the total mass is P ₂ , the P ₂ is 0.1 to 3% by mass, with respect to the P ₁ and P ₂ , 0.5≦P ₂ /P ₁ ≦5, X in the formula (1) is a hydrogen atom or a methyl group, and Y ₁ and Y ₂ in the formula (2) are each independent and must be a hydrogen atom, a hydroxy group, or an amino group (except when both Y ₁ and Y ₂ are hydrogen atoms).
Furthermore, a water-based ball-point pen containing the ink composition and comprising, as a pen tip, a ball-point pen tip consisting of a tip body and a metal ball provided at the front end of the tip body, the ball-point pen 2. An ink occluding body made of a bundle of fibers is incorporated in the barrel, the ink occluding body is impregnated with the ink composition, and the ink is guided from the ink occluding body to the ball-point pen tip. The ballpoint pen is provided with an ink guide core, the tip body is made of synthetic resin, and the ball receiving seat is integrally formed inside the tip body.

The present invention provides a water-based ink composition that is applied to a ball-point pen having a metal ball. Even if there is, it suppresses writing defects such as blurring and line skipping at the time of writing, and in particular, good handwriting even when stored for a long period of time with the writing tip facing upward (upright state) can be formed, and a water-based ink composition for ball-point pens and a water-based ball-point pen containing the same can be provided.

The aqueous ink composition for ballpoint pens according to the present invention (hereinafter sometimes referred to as "aqueous ink composition", "ink composition", or "ink") comprises at least a dye and a compound represented by the above formula (1) a ballpoint pen tip comprising a tip body and a metal ball provided at the front end of the tip body as a pen tip, Applies to ballpoint pens. Each component constituting the water-based ink composition according to the present invention will be described below.

The ink composition according to the invention contains a dye as a coloring agent. The dye is not particularly limited as long as it can be dissolved or dispersed in an aqueous medium, and includes acid dyes, basic dyes, direct dyes, and the like.

Acid dyes include, for example, Naphthol Green B (CI 10020), Naphthol Yellow S (CI 10316), Acid Yellow 9 (CI 13015), Methanil Yellow (CI 13015). I. 13065), Orange I (CI 14600), Ponceau SX (CI 14700), Orange II (CI 15510), Sunset Yellow FCF (CI 15985), New Coxin (CI 16255), First Acid Magenta (CI 17200), Acid Fast Red 3G (CI 18050), First Light Yellow 3G (CI 18820), Tartrazine (CI 19140) ), Resorcinol Brown (CI 20170), Acid Blue 29 (CI 20460), Naphthol Blue Black (CI 20470), Acid Orange 56 (CI 22895), Acid Yellow 42 (C .I.22910), Guinea Green B (CI42085), Fast Green FCF (CI42053), Brilliant Blue FCF (CI42090), Acid Violet 6B (CI42640), Acid Blue 1 (CI 42045), Brilliant Blue G (CI 42655), Brilliant Blue P-1 (CI 42735), Water Blue (CI 42755), Erio Green B (C) 44025), Acid Red (CI 45100), Violamine R (CI 45190), Uranine (CI 45350), Eosin (CI 45380), Phloxine B (CI .45410), erythrosine (CI 45430), nigrosine (CI 50420), pyranine conch (CI 59040), alizrol purple (CI 60730), alizarin cyanine green F (CI .61570), indigo carmine (CI 73015), and the like.

Basic dyes include, for example, chrysoidine (CI 11270), methyl violet (CI 42535), crystal violet (CI 42555), malachite green (CI 42000), Victoria Blue FB. (CI 44045), Rhodamine B (CI 45170), Acridine Orange (CI 46005), Methylene Blue B (CI 52015), Victoria Pure Blue (CI 42595), etc. I can give an example.

Direct dyes include, for example, Congo Red (CI 22120), Direct Sky Blue (CI 24400), Direct Violet 51 (CI 27905), Direct Black 38 (CI 30235), Examples include Kayaras Black G Conch (CI 35225), Direct Black 19 (CI 35255), Phthalocyanine Blue (CI 74180), and the like.

The above dyes can be used singly or in combination of two or more.
Also, the content of the dye with respect to the total mass of the ink composition is not particularly limited, but is preferably in the range of 1 to 50% by mass, more preferably 5 to 30% by mass. If the content of the dye exceeds 50% by mass, the ink ejection stability of the ball-point pen containing the ink composition is lowered, and writing defects such as blurring and line skipping are likely to occur. On the other hand, if the content is less than 1% by mass, it becomes difficult to obtain a suitable handwriting density for a ballpoint pen.

（式中、Ｘは、水素原子、炭素数１～４のアルキル基、カルボキシ基、又はニトロ基である）
上記の化合物は、金属類に対して吸着して被膜を形成する性質を有しており、インキ組成物を収容するボールペンに備えられる金属製のボールペンチップ（以下、「チップ」と表すことがある）、特に、金属製のチップ本体やボールの腐食を抑制する防錆剤としての効果を奏する。 The ink composition according to the present invention comprises a compound represented by the following formula (1). The compound represented by formula (1) is a benzotriazole compound.

(Wherein, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a carboxy group, or a nitro group)
The compound described above has the property of adsorbing to metals to form a film, and the metal ball-point pen tip (hereinafter sometimes referred to as "tip") provided in the ball-point pen containing the ink composition. ), in particular, it is effective as a rust preventive for suppressing corrosion of metal tip bodies and balls.

The content of the compound represented by formula (1) (hereinafter sometimes referred to as “P ₁ ”) relative to the total mass of the ink composition is not particularly limited, but is preferably 0.1 to 3. % by mass, more preferably 0.3 to 2% by mass, still more preferably 0.3 to 1% by mass. When the content of the compound represented by formula (1) is within the above range, the effect of suppressing corrosion of the metal ball-point pen tip is excellent.
As X, a hydrogen atom or a methyl group is preferable because it is excellent in the effect of suppressing corrosion of the metallic tip body and ball in the ink composition.

The ink composition according to the present invention is characterized by the combined use of the compound represented by the above formula (1) and the compound represented by the following formula (2) or a salt thereof. Specifically, by including the compound represented by the formula (1) and the compound represented by the formula (2) or a salt thereof in the ink composition, the metal ball-point pen tip, particularly, The effect of improving the affinity for metal balls can be exhibited. As a result, the ink can be easily guided to the vicinity of the ball provided at the tip of the ballpoint pen, and the ink can be sufficiently held in the vicinity of the ball. It is possible to obtain an ink composition that can form a good handwriting by applying the ink composition, and furthermore, has a smooth writing feeling. In addition, since this effect is maintained over a long period of time, even when the ball-point pen containing the ink composition according to the present invention is stored for a long period of time with the writing tip facing upward. , the ball-point pen exhibits excellent writing performance, as well as being able to form good handwriting and exhibiting a smooth writing feeling.

〔式中、Ｙ_１及びＹ_２は、それぞれ独立に、水素原子、ヒドロキシ基、炭素数１～４のアルキル基、炭素数１～３のアルコキシ基、アミノ基、又は炭素数１～４のアルキル置換アミノ基である（但し、Ｙ_１及びＹ_２が共に、水素原子である場合は除く）〕
式（２）で示される化合物の塩としては、アルカリ金属塩、アンモニウム塩、アルカノールアミン塩等の塩が挙げられる。
また、本発明によるインキ組成物において、式（２）で示される化合物とその塩とを併用して用いることもできる。 The ink composition according to the present invention comprises a compound represented by the following formula (2) and/or a salt thereof. A compound represented by the following formula (2) is a naphthalenedisulfonic acid compound.

[In the formula, Y ₁ and Y ₂ are each independently a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an amino group, or an alkyl group having 1 to 4 carbon atoms. a substituted amino group (except when both Y ₁ and Y ₂ are hydrogen atoms)]
Salts of the compound represented by formula (2) include salts such as alkali metal salts, ammonium salts and alkanolamine salts.
Moreover, in the ink composition according to the present invention, the compound represented by formula (2) and a salt thereof can be used in combination.

Examples of compounds represented by formula (2) include
4-hydroxynaphthalene-2,7-disulfonic acid,
4-methylnaphthalene-2,7-disulfonic acid,
4-ethylnaphthalene-2,7-disulfonic acid,
4-n-butylnaphthalene-2,7-disulfonic acid,
4-ethoxynaphthalene-2,7-disulfonic acid,
4-aminonaphthalene-2,7-disulfonic acid,
4-methylaminonaphthalene-2,7-disulfonic acid,
4-n-propylaminonaphthalene-2,7-disulfonic acid,
4-(N,N-diethylamino)naphthalene-2,7-disulfonic acid,
4-(N-methyl-N-ethylamino)naphthalene-2,7-disulfonic acid,
4,5-dihydroxynaphthalene-2,7-disulfonic acid,
4,5-dimethylnaphthalene-2,7-disulfonic acid,
4,5-di-n-propylnaphthalene-2,7-disulfonic acid,
4,5-dimethoxynaphthalene-2,7-disulfonic acid,
4,5-di-tert-butoxynaphthalene-2,7-disulfonic acid,
4,5-diaminonaphthalene-2,7-disulfonic acid,
4,5-di-ethylaminonaphthalene-2,7-disulfonic acid,
4,5-di-(N,N-dimethylamino)naphthalene-2,7-disulfonic acid,
4,5-di-(N-methyl-N-ethylamino)naphthalene-2,7-disulfonic acid,
4-hydroxy-5-methylnaphthalene-2,7-disulfonic acid,
4-hydroxy-5-ethoxynaphthalene-2,7-disulfonic acid,
4-hydroxy-5-aminonaphthalene-2,7-disulfonic acid,
4-hydroxy-5-ethylaminonaphthalene-2,7-disulfonic acid,
4-methyl-5-tert-butylnaphthalene-2,7-disulfonic acid,
4-methyl-5-methoxynaphthalene-2,7-disulfonic acid,
4-methyl-5-aminonaphthalene-2,7-disulfonic acid,
4-methyl-5-n-propylaminonaphthalene-2,7-disulfonic acid,
4-ethyl-5-(N,N-diethylamino)naphthalene-2,7-disulfonic acid,
4-ethyl-5-(N-methyl-N-ethylamino)naphthalene-2,7-disulfonic acid,
4-methoxy-5-aminonaphthalene-2,7-disulfonic acid,
4-methoxy-5-methylaminonaphthalene-2,7-disulfonic acid,
4-ethoxy-5-(N,N-dimethylamino)naphthalene-2,7-disulfonic acid,
4-n-propoxy-5-methylaminonaphthalene-2,7-disulfonic acid,
4-amino-5-methylaminonaphthalene-2,7-disulfonic acid,
4-amino-5-(N,N-dimethylamino)naphthalene-2,7-disulfonic acid,
Examples include 4-amino-5-(N,N-di-n-propylamino)naphthalene-2,7-disulfonic acid.

As described above, the ink composition according to the present invention uses the compound represented by the formula (1) and the compound represented by the formula (2) or a salt thereof in combination, and the metal tip of the ink composition Affinity for the main body and the ball is improved, ink can be easily guided to the pen tip (writing tip), and ink can be sufficiently retained in the vicinity of the ball. As a result, even after the ballpoint pen containing the ink composition has been stored for a long period of time, the ink composition can be made to have excellent initial writing performance and a smooth writing feel. This is attributed to the adsorption of metals possessed by the benzotriazole compound represented by formula (1) and the interaction between the compound represented by formula (1) and the compound represented by formula (2) or a salt thereof. guessed. That is, the compound represented by the formula (1) is adsorbed to the metal tip body or ball, and the compound represented by the formula (2) or a salt thereof acts on the compound represented by the formula (1), whereby both compounds is adsorbed to the metal tip body or ball, and is presumed to improve the affinity of the ink composition for the metal tip body or ball. As a result, the ink composition can be easily guided to the pen tip, and the ink can be sufficiently retained in the vicinity of the ball. In addition, it is possible to obtain an ink composition that exhibits a smooth writing feeling.

The content of the compound represented by formula (2) and/or a salt thereof (hereinafter sometimes referred to as “P ₂ ”) relative to the total mass of the ink composition is not particularly limited, but is preferably It ranges from 0.1 to 3% by mass, more preferably from 0.5 to 1% by mass. When the content of the compound represented by formula (2) and/or its salt is within the above range, it becomes easier to appropriately interact with the compound represented by formula (1).

In the present invention, the ratio of the content (P ₁ ) of the compound represented by formula (1) to the content (P ₂ ) of the compound represented by formula (2) and/or a salt thereof (P ₂ /P ₁ ) preferably satisfies the following formula (3).
0.5≦P ₂ /P ₁ ≦5 (3)
Regarding P ₂ /P ₁ , it is more preferable to satisfy 1≦P ₂ /P ₁ ≦4. When P ₂ /P ₁ is within the above range, the effect of improving the affinity of the ink composition for the metal tip body and the ball is excellent, and the ink composition can be made excellent in initial writing performance. .

In addition, the compound represented by formula (1) and the compound represented by formula (2) or a salt thereof are likely to interact with each other, making it easier to improve the initial writing performance. As a compound represented by X is a hydrogen atom or a methyl group, and as a compound represented by formula (2) or a salt thereof, Y ₁ and Y ₂ are each independently a hydrogen atom, a hydroxy group, or an amino A combination with a compound or a salt thereof which is a group (except when Y ₁ and Y ₂ are both hydrogen atoms) is preferred. A more preferable combination is a compound represented by formula (1) in which X is a hydrogen atom or a methyl group, and a compound represented by formula (2) or a salt thereof in which one of Y ₁ and Y ₂ is amino group and the other is a hydroxy group, or a combination with a salt thereof.

The ink composition according to the invention comprises water.
Water is not particularly limited, and examples thereof include tap water, ion-exchanged water, ultrafiltered water, and distilled water.
The water content relative to the total weight of the ink composition is not particularly limited, but is preferably in the range of 30 to 80% by weight, more preferably 40 to 70% by weight.

In addition to the essential components described above, the ink composition according to the present invention may contain optional components within a range that does not impair the effects of the present invention.

The ink composition according to the present invention may contain a thickening agent. By blending a thickener, an ink composition having good stability over time can be obtained.
As the thickening agent, conventionally known substances can be used, but it is preferable to use a substance capable of imparting shear thinning property to the ink composition (shear thinning agent). An ink composition using a shear-thinning agent has a high viscosity when it is left standing or when the stress is low and does not easily flow. can be prevented from leaking out, and the separation and backflow of ink can be prevented. In particular, when such an ink composition is used in a writing instrument having a ballpoint tip as a pen tip (ballpoint pen), the viscosity is high when the ink composition is left stationary without shearing stress applied, so that the ink composition stably stays in the ballpoint pen. When the ball is held, a strong shearing stress is applied to the ink composition by the rotation of the ball during writing, and the viscosity of the ink composition in the vicinity of the ball is easily lowered, so that the ink ejection stability can be improved.
When the ink composition according to the present invention contains a thickener, the content of the thickener with respect to the total weight of the ink composition is not particularly limited, but is preferably in the range of 0.1 to 20% by weight. be.

Shear-thinning agents include, for example, water-soluble polysaccharides, polymers having a molecular weight of 100,000 to 150,000 mainly composed of alkyl esters of methacrylic acid, poly-N-vinylcarboxylic acid amide cross-linked products, benzylidene sorbitol and their Examples include derivatives, benzylidene xylitol and its derivatives, alkali-thickening acrylic resins, crosslinkable acrylic acid polymers, inorganic fine particles, nonionic surfactants with an HLB value of 8 to 12, metal salts and amine salts of dialkylsulfosuccinic acid, etc. can.
The shear thinning agent can be used alone or in combination of two or more.

Examples of water-soluble polysaccharides include xanthan gum, welan gum, zetasea gum, diutan gum, macrohomopsis gum, and succinoglycan (average molecular weight of about 1 million to 8 million), guar gum, locust bean gum and its derivatives, hydroxyethylcellulose, alginic acid alkyl esters, glucomannan, carbohydrates with gelling ability extracted from seaweed such as agar and carrageenin.

The ink composition according to the present invention can be blended with a surfactant to adjust the surface tension of the ink composition to an appropriate range.
Surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and the like, and any of them can be suitably used.
Examples of surfactants include phosphate ester surfactants, silicone surfactants, surfactants having an acetylene bond in their structure, fluorine surfactants, and the like. It is appropriately selected according to the components of the ink composition, the application, and the like.
When the ink composition according to the present invention contains a surfactant, the content of the surfactant with respect to the total mass of the ink composition is not particularly limited, but is preferably 0.01 to 2% by mass, more preferably is in the range of 0.05 to 1% by mass.

The ink composition according to the present invention can be blended with a pH adjuster to adjust the pH of the ink composition to an appropriate range. Various acidic substances and basic substances can be used as the pH adjuster.
Examples of acidic substances include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, lactic acid, citric acid, tartaric acid, and malic acid.
Examples of basic substances include ammonia, sodium carbonate, sodium hydrogen phosphate, potassium hydrogen phosphate, sodium hydroxide, potassium hydroxide, sodium acetate and the like, and alkanols such as monoethanolamine, diethanolamine and triethanolamine. Amines can also be applied.
When the ink composition according to the present invention contains a pH adjuster, the content of the pH adjuster with respect to the total mass of the ink composition is not particularly limited, but is preferably 0.1 to 5% by mass, more preferably is in the range of 0.5 to 2% by mass.

The ink composition according to the present invention can be blended with a water-soluble organic solvent that is compatible with water, so that evaporation of water from the nib of the pen can be suppressed.
Examples of water-soluble organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thioethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, and ethylene glycol monomethyl. ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2- Pyrrolidone and the like can be exemplified.
The water-soluble organic solvent can be used alone or in combination of two or more.
When the ink composition according to the present invention contains a water-soluble organic solvent, the content of the water-soluble organic solvent relative to the total weight of the ink composition is not particularly limited, but is preferably 1 to 40% by weight, more preferably 1 to 40% by weight. is in the range of 5 to 30% by mass, more preferably 10 to 25% by mass. If the content of the water-soluble organic solvent exceeds 40% by mass, the viscosity of the ink tends to increase, and the ink ejection property of the ballpoint pen containing the ink composition tends to decrease, resulting in writing defects such as blurring and line skipping. On the other hand, if the blending ratio is less than 1% by mass, the effect of suppressing water evaporation is poor.

The ink composition according to the present invention may contain water-soluble resins such as alkyd resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin. Viscosity can also be imparted.
The water-soluble resin can be used alone or in combination of two or more.
When the ink composition according to the present invention contains a water-soluble resin, the content of the water-soluble resin with respect to the total mass of the ink composition is not particularly limited, but is preferably 1 to 30% by mass, more preferably 1 It is in the range of ~10% by mass.

Various additives can also be added to the ink composition according to the present invention, if necessary.
Examples of additives include
Rust inhibitors such as dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, etc.
carbolic acid, sodium salt of 1,2-benzothiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl parahydroxybenzoate, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine preservatives or antifungal agents such as
Ascorbic acids, erythorbic acids, α-tocopherol, catechins, synthetic polyphenols, kojic acid, alkyl hydroxylamines, oxime derivatives, α-glucosylrutin, α-lipoic acid, phosphonates, phosphinates, sulfites, sulfoxylates , dithionite, thiosulfate, thiourea dioxide and other foam absorbents,
Wetting agents such as reduced or non-reduced starch hydrolysates, disaccharides such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, sodium pyrophosphate, etc.
Antifoaming agents, dispersants, specific gravity modifiers and the like can be exemplified.
In addition, the basic substance described above can be blended as a neutralizing agent for the compound represented by formula (2).

The ink composition according to the present invention can also contain a lubricant. The lubricant improves the lubricity between the ball seat provided inside the tip body and the ball provided at the front end of the tip body, thereby easily preventing wear of the ball seat and improving the writing feel. It is something that can be done.
Examples of lubricants include higher fatty acids such as oleic acid, nonionic surfactants having long-chain alkyl groups, polyether-modified silicone oils, tri(alkoxycarbonylmethyl) thiophosphite and tri(alkoxycarbonyl) thiophosphite. thiophosphite triesters such as ethyl esters), phosphoric acid monoesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, phosphoric acid diesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, and metals thereof Phosphate surfactants such as salts, ammonium salts, amine salts, and alkanolamine salts can be exemplified.

When applying the ink composition according to the present invention to a ball-point pen having a ball-point pen tip composed of a tip body provided with a metal ball receiving seat and a metal ball, a phosphoric acid ester-based surfactant is used as a lubricant. is preferably used.
Phosphate ester-based surfactants have the property that the phosphate group easily adsorbs to metals. The surfactant adheres to the ball and the ball seat to form a lubricating layer composed of a phosphoric acid ester surfactant on the surface of the ball and the surface of the ball seat, thereby improving lubricity between the ball and the ball seat. It can be improved to rotate the ball smoothly. In addition, it is possible to suppress wear of the ball receiving seat and improve writing feeling such as writing feeling.

The method for producing the ink composition according to the present invention is not particularly limited, and any conventionally known method can be used. Specifically, the ink composition is obtained by stirring the mixture containing the above components with various stirrers such as propeller stirring, homodisper, or homomixer, or by dispersing with various dispersers such as bead mills. can manufacture things.

In the water-based ink composition of the present invention, the viscosity characteristics are not particularly limited. An ink composition having viscosity characteristics such as a shear-thinning ink composition (Newtonian ink) can be used, and among these, a low-viscosity ink composition is preferably used.
The viscosity of the ink composition according to the present invention is not particularly limited, but is preferably 1 to 30 mPa·s, more preferably 1 to 20 mPa when measured at a rotation speed of 20 rpm in an environment of 20°C. ·s, more preferably in the range of 1 to 10 mPa·s. When the viscosity is within the above range, it is possible to obtain an ink composition that has stable ink ejection properties from the nib of a ball-point pen, suppresses poor writing such as blurring and line skipping, and forms good handwriting. easier.
The viscosity was measured using an E-type rotational viscometer [manufactured by Toki Sangyo Co., Ltd., product name: RE-85L, cone-shaped rotor: standard type (1°34′×R24)]. It is a value measured in an environment of °C.

Although the surface tension of the ink composition according to the present invention is not particularly limited, it is preferably in the range of 20 to 50 mN/m, more preferably 25 to 45 mN/m in an environment of 20°C. When the surface tension is within the above range, bleeding of writing lines and strike-through to the paper surface can be easily suppressed, and the wettability of the ink to the paper surface can be improved.
The surface tension was measured using a surface tension measuring instrument [manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300], the ink was placed in an environment of 20 ° C., and the vertical plate method using a platinum plate. It is a measured value.

Although the pH of the ink composition according to the present invention is not particularly limited, it is preferably in the range of 6-11, more preferably 7-10. When the pH is within the above range, the compound represented by formula (2) or a salt thereof in the ink composition has excellent dissolution stability, and it becomes easy to prevent corrosion of the metal ball-point pen tip by the ink. .
The pH is a value measured by placing the ink in an environment of 20° C. using a pH meter (manufactured by Toa DKK Co., Ltd., product name: IM-40S).

The ink composition according to the present invention is used by being housed in a ball-point pen provided with a ball-point pen tip consisting of a tip body, a metal ball provided at the front end of the tip body, and an ink filling mechanism.

Ballpoint pen tips include, for example, a tip in which a metal ball is held in a ball holding portion in which the vicinity of the tip of a metal pipe is pressed and deformed inward from the outer surface, and a tip made by cutting a metal material with a drill or the like. A chip in which a metal ball is held in the formed ball holding portion, a chip in which a resin ball receiving seat is provided inside a metal or synthetic resin chip body, or a ball held in the above chip. For example, one that is urged forward by a spring body can be exemplified.

The material of the ball is not particularly limited as long as it is made of metal, and examples thereof include cemented carbide (carbide) and stainless steel.
The applicable diameter of the ball (hereinafter sometimes referred to as “ball diameter”) is generally 0.1 to 3 mm, preferably 0.3 to 2 mm, more preferably 0.3 to 1 mm.

An example of the ink filling mechanism is an ink storage tube that can be filled with the ink composition.

As the ink storage tube, for example, a molding made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a metal tubular body is used.
A ballpoint pen refill (hereinafter sometimes referred to as "refill") is formed by filling an ink containing tube to which the above tip is connected directly or via a connecting member with the ink composition according to the present invention. can be done. A ball-point pen can be formed by housing this refill in the barrel.

The trailing end of the ink filled in the ink storage tube is filled with an ink backflow prevention member. Ink backflow preventers include liquid plugs or solid plugs.
The liquid plug consists of a non-volatile liquid and/or a sparingly volatile liquid, such as petroleum jelly, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefins, oligomers or co-oligomers of α-olefins, dimethyl Examples include silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, and fatty acid-modified silicone oil.
The nonvolatile liquid and/or the hardly volatile liquid can be used singly or in combination of two or more.

It is preferable to add a thickening agent to the non-volatile liquid and/or the low-volatility liquid to increase the viscosity to a suitable viscosity.
Examples of thickening agents include silica whose surface is hydrophobically treated, fine particle silica whose surface is methylated, aluminum silicate, swelling mica, clay-based thickeners such as bentonite and montmorillonite, which are hydrophobically treated, and magnesium stearate. , fatty acid metal soaps such as calcium stearate, aluminum stearate, and zinc stearate; tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene waxes; hydrogenated castor oil; .

Examples of solid plugs include solid plugs made of polyethylene, polypropylene, and polymethylpentene.
As an ink backflow preventer, the liquid plug and the solid plug can be used in combination.

A ball-point pen can also be formed by using the barrel itself as an ink filling mechanism, attaching a tip to the front end of the barrel, and directly filling the barrel with ink.

A ball-point pen having a ball-point pen tip consisting of a tip body and a metal ball provided at the front end of the tip body as a pen tip, and an ink filling mechanism further includes an ink composition filled in the ink filling mechanism. An ink supply mechanism for supplying ink first may be provided.

The ink supply mechanism is not particularly limited, and includes, for example, (1) a mechanism equipped with an ink guide wick made of a fiber bundle or the like as an ink flow rate controller to supply ink to the pen tip; A mechanism for supplying ink to the nib through which an ink flow rate adjusting body is interposed; (3) A large number of discs are arranged in parallel with a comb groove-like interval, and are slit-shaped and extend axially through the discs. The pen core is provided with an ink guide groove and a ventilation groove wider than the groove, and an ink guide core for guiding ink from the ink filling mechanism to the pen tip is arranged at the center of the pen core. A mechanism for supplying first, and the like can be mentioned.
The material of the pen core is not particularly limited as long as it is a synthetic resin that can be injection-molded into a structure in which a large number of discs are shaped like comb grooves. Examples of the synthetic resin include general-purpose polycarbonate, polypropylene, polyethylene, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and the like. In particular, acrylonitrile-butadiene-styrene copolymer resin (ABS resin) is preferably used because it has high moldability and is easy to obtain pen core performance.

When the ball-point pen is provided with an ink supply mechanism, the ink filling mechanism may be one that is configured to directly fill with ink, or one that is provided with an ink containing body or ink absorbing body capable of being filled with ink.

The ink occluding body is a fiber bundle formed by bundling crimped fibers in the longitudinal direction. adjusted and configured.

Furthermore, the ink filling mechanism can be in the form of an ink cartridge as a detachable structure. In this case, after the ink contained in the ballpoint pen body has been used up, it can be used by replacing it with a new cartridge.
As the ink cartridge, there is used one that is connected to the ballpoint pen main body and also serves as a barrel that constitutes the ballpoint pen, and one that covers and protects the barrel (rear barrel) after being connected to the ballpoint pen main body. In the latter, in addition to using the ink cartridge alone, the ballpoint pen body and the ink cartridge are connected before use, and the user starts using by connecting the ink cartridge inside the barrel when using it. As shown in FIG. 1, any one of those accommodated in the shaft cylinder in a non-connected state may be used.

If the ball-point pen containing the ink composition according to the present invention comprises a pen tip and an ink filling mechanism, or comprises a pen tip, an ink filling mechanism and an ink supply mechanism, The structure and shape of the ballpoint pen itself are not particularly limited.
For example, the ballpoint pen may be configured as follows: (1) An ink containing tube filled with ink is provided in the barrel, and a ballpoint pen tip is connected directly or via a connecting member to the ink containing tube. is a ballpoint pen filled with an ink backflow preventer; , a ballpoint pen equipped with a mechanism for supplying ink to the pen tip; ) An ink-absorbing body consisting of a bundle of fibers impregnated with ink is built into the barrel, and an ink guide core made of a bundle of fibers is interposed as an ink flow control body to supply ink to the nib. A ballpoint pen or the like can be exemplified.

Furthermore, the ball-point pen with the above configuration is provided with a cap that is attached so as to cover the pen tip (writing tip) to make it a cap-type ball-point pen, thereby preventing the pen tip from drying out and making it impossible to write. can be prevented from being contaminated or damaged.

In addition, the ball-point pen in which the ball-point pen refill is stored in the barrel can be made into a retractable ball-point pen by providing a retractable mechanism that allows the writing tip to retract and retract from the barrel.・It can be prevented from being damaged.
Any retractable ballpoint pen can be used as long as it has a structure in which the writing tip is stored in the barrel with the writing tip exposed to the outside air, and the writing tip protrudes from the barrel opening by the operation of the retraction mechanism. .

As a refill to be stored in a retractable ballpoint pen, for example, an ink storage tube is filled with ink, a ballpoint pen tip is attached to one end of the ink storage tube, and the other end of the ink storage tube is attached so as to be in close contact with the end face of the ink to prevent backflow of ink. An ink absorbing body impregnated with ink is built in a refill filled with a body or an ink containing tube, a ball-point pen tip is attached to one end of the ink containing tube, and ink is guided from the ink absorbing body to the ball-point pen tip. can be exemplified as a refill or the like with an ink guide wick.
A retractable ball-point pen can be obtained by housing these refills in the barrel and having a structure in which the writing tip protrudes from the opening of the barrel by the operation of the retractable mechanism.

For example, (1) an operating portion (clip) movable in the front-rear direction is protruded radially outward from the rear side wall of the barrel, and the operating portion is slid forward to open the front end of the barrel. (2) A rear end knock that causes the writing tip to appear and retract from the front end opening of the barrel by pushing forward an operation part provided at the rear end of the barrel. (3) a side-knock type retracting mechanism for retracting the writing tip from the front end opening of the barrel by pressing an operating portion protruding from the outer surface of the side wall of the barrel radially inward; A rotating retractable mechanism or the like that retracts and retracts the writing tip from the front end opening of the barrel can be exemplified by rotating the operating portion at the rear portion of the cylinder.

The form of the ballpoint pen is not limited to the configuration described above. In addition to attaching tips with different ball diameters, attaching pen tips that lead out inks of different color tones, attaching tips with different ball diameters, A composite ball-point pen (double-ended type, pen-tip feeding type, etc.) in which the color tone of the ink derived from each tip is different may be used.
Further, it is also possible to provide a composite type retractable ballpoint pen in which a plurality of ballpoint pen refills are accommodated in the barrel, and the writing tip of any one of the refills is retracted from the opening of the barrel by the actuation of the retraction mechanism.

A ball-point pen preferable in the present invention has a ball-point pen tip consisting of a tip body and a metal ball provided at the front end of the tip body as a pen tip, and a shaft cylinder as an ink filling mechanism, which is impregnated with ink. An ink occluding body made of a bundle or the like is built in, and an ink guide core made of a fiber bundle or the like as an ink supply mechanism is connected to the front end of the ink occluding body and to a ball receiving seat provided inside the tip body. It is a formula ballpoint pen.
The ball-point pen having the above structure supplies ink to the pen tip by utilizing capillary force, and the ink guide core connected to the front end of the ink absorbing body is connected to the ball seat provided inside the tip body. As a result, the ink is guided from the ink occluding body to the vicinity of the ball to enable writing. Since it is difficult to retain the ink in the ink, the initial writing performance may be a problem. However, the ink composition according to the present invention has an excellent affinity for the metal tip body and the ball, and the ink is easily guided to the pen tip, especially near the metal ball, so that the ink can be sufficiently retained in the vicinity of the ball. Therefore, it is preferably used for the ballpoint pen (stuffed ballpoint pen) having the above configuration.

In addition, a ball-point pen comprising a ball-point pen tip consisting of a tip body having a synthetic resin ball receiving seat inside and a metal ball provided at the front end of the tip body as a pen tip is also preferable in the present invention. Used.
The tip body provided with the synthetic resin ball seat is not particularly limited as long as the synthetic resin ball seat is provided inside the tip body made of metal or synthetic resin.
The ball receiving seat made of synthetic resin is provided with a central hole and a plurality of (for example, five) ink guide holes extending radially outward from the central hole. have. As a result, it becomes possible to supply the ink filled in the ink filling mechanism to the vicinity of the ball via the ink supply mechanism such as the ink guide wick.

A chip with a ball receiving seat made of synthetic resin has high elasticity and is easily deformed elastically as the ball rotates. Rotation is smooth, and the feeling of writing with a ballpoint pen can be made smooth.
The ball-point pen containing the ink composition according to the present invention retains the ink sufficiently near the ball and provides a smooth writing feeling. By applying the tip, it is possible to further improve the smooth writing feeling, so it is preferably used for the ball-point pen having the above configuration.

A chip body having a ball receiving seat made of synthetic resin can be obtained, for example, by injection molding of polyacetal resin. Specifically, when the chip body is molded, the ball receiving seat is integrally formed inside the chip body. can do. By holding a metal ball in the front end of the tip body, a ball-point pen tip provided with a synthetic resin ball receiving seat can be obtained.
In general, a ball-point pen tip consists of a tip body with a metal ball seat and a metal ball provided at the front end of the tip body. As a result, the paper is likely to be scraped off, which may impair the feeling of writing. In addition, there are many processing steps for metal members when manufacturing a ballpoint pen tip, and there have been problems of low productivity and high cost. However, a ball-point pen tip consisting of a tip body made of synthetic resin and having a ball receiving seat integrally formed inside the tip body, and a metal ball provided at the front end of the tip body, is different from the above-mentioned metal ball. In addition to the smooth rotation of the tip body, even if the front end of the tip body hits the paper surface during writing, it is difficult to scrape the paper, making it possible to provide a smooth writing feeling. Furthermore, since the ball receiving seat can be formed at the same time when the tip body is molded, the number of processing steps is reduced, and the productivity of the tip is excellent.
The ball-point pen containing the ink composition according to the present invention retains the ink sufficiently near the ball and provides a smooth writing feeling. Smooth writing feeling can be further improved by applying the chip integrally formed inside the ballpoint pen, and thus the ballpoint pen having the above configuration is suitably used.

A ball-point pen (cap-type ball-point pen) provided with a cap attached so as to cover the pen tip (writing tip) is also preferably used in the present invention. A ball-point pen containing a water-based ink composition tends to have a dry nib, which tends to cause poor writing. It is possible to prevent the writing tip from being contaminated and damaged.

A ball-point pen containing the ink composition according to the present invention has a ball-point pen tip consisting of a tip body and a metal ball provided at the front end of the tip body as a pen tip, and an ink filling mechanism in a barrel as an ink filling mechanism. An impregnated ink occluding body is built in, an ink guide core as an ink supply mechanism is connected to the front end of the ink occluding body and a ball receiving seat provided inside the tip body, and a cap is attached so as to cover the writing tip. A mounted ballpoint pen is a more preferred ballpoint pen. The ball-point pen having the above-described configuration easily guides the ink to the vicinity of the ball, and even after being stored for a long period of time, it has excellent initial writing performance and provides a smooth writing feeling, and the pen tip does not easily dry. It is used more preferably because it is excellent in writing performance.
In the ball-point pen having the above configuration, a ball-point pen having a tip consisting of a tip body provided with a ball receiving seat made of synthetic resin and a metal ball provided at the front end of the tip body as a ball-point pen tip is as described above. In addition to the above effects, the metal ball rotates smoothly and provides a smooth writing feeling, so it is more preferably used.

The most preferred ballpoint pen of the present invention is the ballpoint pen having the above structure, in which the ballpoint pen tip is provided at the front end of the tip body, which is made of synthetic resin and in which the ball receiving seat is integrally formed inside the tip body. A stuffed ball-point pen having a ball-point pen tip made of a metal ball and having excellent initial writing performance even after being stored for a long period of time. The metal ball rotates smoothly, and even if the front end of the tip body hits the paper surface during writing, it does not easily scrape the paper. In addition, since the ball receiving seat can be formed at the same time when the tip body is molded, the productivity of the tip is excellent.

Examples are shown below, but the present invention is not limited thereto. In addition, unless otherwise specified, "parts" in the examples indicate "mass parts".

Example 1
Preparation of water-based ink composition 5.5 parts of red dye [manufactured by Hodogaya Chemical Co., Ltd., product name: phloxine] and 1.5 parts of orange dye [manufactured by Orient Chemical Industry Co., Ltd., product name: WATER ORANGE 18] part, 0.5 part of benzotriazole [manufactured by Daiwa Kasei Co., Ltd., product name: VERZONE Crystal #120], 0.2 part of 4-hydroxy-5-aminonaphthalene-2,7-disulfonic acid, and nonionic Surfactant [manufactured by Nikko Chemicals Co., Ltd., product name: NIKKOL BC-10] 0.1 part, glycerin 20 parts, and dextrin [manufactured by Nikko Chemicals Co., Ltd., product name: Akadama Dextrin No. 102-S] 2.5 parts, triethanolamine 0.9 parts, antiseptic [Lonza Japan Co., Ltd., product name: Proxel XL-2 (S)] 0.5 parts, water 68.3 were mixed to prepare an aqueous ink composition.
Further, the content ratio (P ₁ ) of the compound represented by formula (1) with respect to the total mass of the ink composition is 0.5, and the content of the compound represented by formula (2) with respect to the total mass of the ink composition _The ratio (P2) was 0.2 and the _ratio of P1 to P2 ₍ P2 _/ P1) was 0.4.

Manufacture of ball-point pen The rear of the ball-point pen tip has a carbide ball with a diameter of 0.8 mm held at the front end of a synthetic resin tip body in which a ball seat is integrally formed by injection molding of polyacetal resin. From the end, an ink guide wick made of polyester fiber was inserted to connect the ball seat and the front end of the ink guide wick. Then, the ball-point pen tip to which the ink guide core was connected was connected to the front end opening of the barrel via a holder. Next, an ink occluding body made of polyester fibers is impregnated with the above ink composition, and this ink occluding body is accommodated in the barrel from the rear end opening of the barrel, and the rear end of the ink guide core and the front end of the ink occlusion body are separated. were connected, and the breech plug was fitted to the rear end opening of the barrel. Furthermore, a cap was attached so as to cover the writing tip, and a ballpoint pen (filled ballpoint pen) was produced.

Using the above ballpoint pen, in a room temperature (20 ° C) environment, 12 elliptical circles (major diameter 15 mm, minor diameter 8 mm) was handwritten in a spiral so that the circles touched each other, and two lines were continuously written. was gotten. Writing paper A conforming to old JIS P3201 was used as the test paper.

Examples 2-11 and Comparative Examples 1-3
A water-based ink composition was prepared in the same manner as in Example 1, except that the types and amounts of the materials to be blended were changed to those shown in Table 1 below. In addition, P ₁ , P ₂ and P ₂ /P ₁ in each water-based ink composition are as shown in Table 1.

A ball-point pen was produced in the same manner as in Example 1. Using each ballpoint pen, in a room temperature (20 ° C) environment, 12 elliptical circles (major diameter 15 mm, minor diameter 8 mm) per line in the direction parallel to the short direction of an A4 size test paper (portrait) degree) was written in a spiral so that the circles touched each other, and two lines were continuously written. , good handwriting was obtained. Writing paper A conforming to old JIS P3201 was used as the test paper.

The contents of the materials in Table 1 are explained along with the note numbers.
(1) Red dye [manufactured by Hodogaya Chemical Industry Co., Ltd., product name: phloxine]
(2) Orange dye [manufactured by Orient Chemical Industry Co., Ltd., product name: WATER ORANGE 18]
(3) Black dye solution [manufactured by Orient Chemical Industry Co., Ltd., product name: WATER BLACK 191-L (solid content: 20%)]
(4) Yellow dye [manufactured by Sumitomo Chemical Co., Ltd., product name: WATER YELLOW 6C]
(5) Benzotriazole [manufactured by Daiwa Kasei Co., Ltd., product name: VERZONE Crystal #120]
(6) Tolyltriazole [manufactured by Daiwa Kasei Co., Ltd., product name: VERZONE TTA]
(7) 4-hydroxy-5-aminonaphthalene-2,7-disulfonic acid (8) 4,5-dihydroxynaphthalene-2,7-disulfonic acid (9) 4-hydroxynaphthalene-2,7-disulfonic acid (10 ) Nonionic surfactant [manufactured by Nikko Chemicals Co., Ltd., product name: NIKKOL BC-10]
(11) Dextrin [manufactured by Nichiden Chemical Co., Ltd., product name: Akadama Dextrin No. 102-S]
(12) Preservative [manufactured by Lonza Japan Co., Ltd., product name: Proxel XL-2 (S)]

Evaluation of initial writing performance after aging at room temperature The ballpoint pens of Examples 1 to 11 and Comparative Examples 1 to 3 were capped and placed in a constant temperature bath set at 20 ° C for 60 days with the tip facing upward (correct standing state). After 60 days, it was removed from the constant temperature bath, and placed in a room temperature (20 ° C.) environment in parallel with the short direction of an A4 size test paper (portrait). Approximately 8 mm in short diameter) was written in two consecutive lines in a spiral shape so that the circles were in contact with each other. Writing paper A conforming to old JIS P3201 was used as the test paper.
The resulting handwriting was visually confirmed and evaluated according to the following criteria. The evaluation results are shown in Table 2 below.
as described in Note that A and B are pass levels for practical use.
A: From the start of writing to the end of writing two lines of circles (24 circles), no faint lines or skipped lines occurred in the handwriting, and good handwriting was obtained.
B: At the beginning of writing, slight fading and line skipping occurred in the handwriting, but the occurrence of fading and line skipping was resolved before the completion of writing one circle, and there was no problem in practical use.
C: Blurs and line skipping occurred in the handwriting from the start of writing, and the occurrence of blurring and line skipping was not resolved until three circles were completed.
D: Blurs and line skipping occurred in the handwriting from the start of writing, and the occurrence of blurring and line skipping was not eliminated even after finishing writing 12 circles (for one line).

Evaluation of initial writing performance after warming over time The ballpoint pens of Examples 1 to 11 and Comparative Examples 1 to 3 were capped and placed in a constant temperature bath set at 40 ° C. for 60 days with the tip facing upward ( standing upright). After 60 days, it was removed from the constant temperature bath, and placed in a room temperature (20 ° C.) environment in parallel with the short direction of an A4 size test paper (portrait). Approximately 8 mm in short diameter) was written in two consecutive lines in a spiral shape so that the circles were in contact with each other. Writing paper A conforming to old JIS P3201 was used as the test paper.
The resulting handwriting was visually confirmed and evaluated according to the following criteria. The evaluation results are shown in Table 2 below.
as described in Note that A and B are pass levels for practical use.
A: From the start of writing to the end of writing two lines of circles (24 circles), no faint lines or skipped lines occurred in the handwriting, and good handwriting was obtained.
B: At the beginning of writing, slight fading and line skipping occurred in the handwriting, but the occurrence of fading and line skipping was resolved before the completion of writing one circle, and there was no problem in practical use.
C: Blurs and line skipping occurred in the handwriting from the start of writing, and the occurrence of blurring and line skipping was not resolved until three circles were completed.
D: Blurs and line skipping occurred in the handwriting from the time of writing, and the occurrence of blurring and line skipping was not eliminated even after finishing writing 12 circles (for one line).

Claims (8)

An aqueous ink composition contained in a ball-point pen comprising, as a pen tip, a ball-point pen tip consisting of a tip body and a metal ball provided at the front end of the tip body, wherein at least a dye and the following formula (1 ), a compound represented by the following formula (2) and/or a salt thereof, and water.

(Wherein, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a carboxy group, or a nitro group)

[In the formula, Y ₁ and Y ₂ are each independently a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an amino group, or an alkyl group having 1 to 4 carbon atoms. a substituted amino group (except when both Y ₁ and Y ₂ are hydrogen atoms)] The water-based ink for a ballpoint pen according to claim 1, wherein P ₁ is 0.1 to 3% by mass, where P ₁ is the content of the compound represented by formula (1) with respect to the total mass of the ink composition. Composition. Where P2 is the content of the compound represented by formula ( ₂ ) and/or a salt thereof with respect to the total mass of the ink composition, P2 is 0.1 to ₃ % by mass, or 3. The water-based ink composition for ballpoint pens according to 2 above. Regarding P ₁ and P ₂ ,
0.5≦P ₂ /P ₁ ≦5
The water-based ink composition for a ball-point pen according to claim 3, which satisfies: X in the formula (1) is a hydrogen atom or a methyl group, and Y ₁ and Y ₂ in the formula (2) are each independently a hydrogen atom, a hydroxy group, or an amino group (provided that 5. The water-based ink composition for a ball-point pen according to any one of claims ₁ to 4, except when _both Y1 and Y2 are hydrogen atoms. A ball-point pen tip containing the ink composition according to any one of claims 1 to 5, and comprising, as a pen tip, a tip body and a metal ball provided at the front end of the tip body. A water-based ballpoint pen. The ball-point pen includes an ink occluding body made of a bundle of fibers in a barrel, the ink occluding body being impregnated with the ink composition, and the ink occluding the ink from the ink occluding body to the ball-point pen tip. 7. A water-based ball-point pen according to claim 6, which is a filling-type ball-point pen provided with an ink guiding core for guiding. 8. The water-based ball-point pen according to claim 6, wherein said tip body is made of synthetic resin, and a ball receiving seat is integrally formed inside said tip body.