Water-based ballpoint pen

Abstract

The objective of this invention is to provide a water-based ballpoint pen that produces a rich and varied handwriting with varying shades, similar to that of a fountain pen, without smudging or bleeding, and that can suppress air bubbles in the water-based ink. [Solution] The present invention relates to a water-based ballpoint pen having a ballpoint pen tip at the end of an ink reservoir, and containing a water-based ballpoint pen ink composition comprising water, a colorant, a polyhydric alcohol, and a bubble absorbent in the ink reservoir, wherein the ball diameter of the water-based ballpoint pen is 0.7 mm or more and 2.0 mm or less, and when the ink consumption per 100 m of the water-based ballpoint pen is A (mg) and the ball diameter is B (mm), the relationship 200 ≤ A / B ≤ 450 is satisfied, and the ink viscosity of the water-based ballpoint pen ink composition is 384 sec at 20°C. -1 A water-based ballpoint pen characterized by having a pressure of 40 mPa·s or less, and a polyhydric alcohol content of 0.1% by mass or more and 10% by mass or less, relative to the total amount of the ink composition.

Description

[Technical Field]

[0001] This invention relates to a water-based ballpoint pen. More specifically, it relates to a water-based ballpoint pen that produces a varied and nuanced handwriting similar to that of a fountain pen, without smudging or bleeding, and that can suppress air bubbles in the water-based ink. [Background technology]

[0002] Conventionally, as an ink composition for ballpoint pens that utilizes the properties of ink with shear-reducing viscosity, for example, an aqueous ballpoint pen ink composition characterized by containing 0.20 to 0.45% by weight of xanthan gum has been developed, which has an appropriate viscosity or fluidity that enables smooth writing with a uniform thickness for various balls, does not cause ink skipping even at high writing speeds, and does not leave ink residue at the tip of the ballpoint pen after writing (see Patent Document 1), and Water-based ballpoint pen ink compositions containing various lubricants to improve writing feel and prevent skipping or smudging of the ink, etc. (see Patent Documents 2 and 3), Furthermore, a water-based ballpoint pen ink composition (see Patent Document 4) has been proposed that contains polyvinyl alcohol and / or polysaccharides, boric acid and its salts, and has dilatant fluid properties, resulting in a smooth writing experience that is less prone to skipping at the beginning of writing, and producing sharp, clean lines with clear stops, hooks, and sweeps, resulting in beautiful characters. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] "Unexamined Japanese Patent Publication No. 59-74175" [Patent Document 2] "Japanese Patent Publication No. 2006-282870" [Patent Document 3] "Unexamined Japanese Patent Publication No. 7-62288" [Patent Document 4] "Japanese Patent Publication No. 2014-95070" [Overview of the project] [Problems that the invention aims to solve]

[0004] Patent documents 1 to 3 describe technologies that allow for writing with a relatively light feel and have the effect of suppressing line breaks and smudging in the handwriting. Furthermore, Patent Document 4 describes a technology that provides a smooth writing feel, good handwriting, and sharp, clean lines.

[0005] However, while Patent Documents 1-4 allow for reasonably neat handwriting during normal writing, many users still felt something was lacking, and there was a desire for more varied handwriting. Furthermore, with water-based ballpoint pen inks, low viscosity inks tend to trap air, leading to residual air bubbles in the ink, which is a common problem and has necessitated improvement.

[0006] The objective of the present invention is to solve the above-mentioned problems and, as a result of diligent research into water-based ballpoint pens, to provide a water-based ballpoint pen that produces a varied handwriting style different from conventional gel inks, resulting in a good handwriting experience. [Means for solving the problem]

[0007] To solve the above problems, the present invention "1. A water-based ballpoint pen having a ballpoint pen tip at the front of an ink reservoir, and containing a water-based ballpoint pen ink composition comprising water, a colorant, a polyhydric alcohol, and a bubble absorbent inside the ink reservoir, The ball diameter of the water-based ballpoint pen is 0.7 mm or more and 2.0 mm or less. If the ink consumption per 100m of a water-based ballpoint pen is A (mg) and the ball diameter is B (mm), then the relationship is 200 ≤ A / B ≤ 450. The ink viscosity of the water-based ballpoint pen ink composition was determined at 20°C and a shear rate of 384 sec. -1 In that case, it is 40 mPa·s or less, An aqueous ballpoint pen characterized in that the content of the polyhydric alcohol is 0.1% by mass or more and 10% by mass or less based on the total amount of the ink composition. 2. The aqueous ballpoint pen according to claim 1, wherein the ink composition for the aqueous ballpoint pen contains a phosphate ester surfactant or a fatty acid, and the content of the surfactant is 0.1 mass or more and 3 mass% or less based on the total amount of the ink composition. 3. The aqueous ballpoint pen according to claim 1 or 2, wherein the colorant is a dye, and the content of the dye is 0.1 mass or more and 4 mass% or less based on the total amount of the ink composition. 4. The aqueous ballpoint pen according to claim 1 or 2, wherein the antifoaming agent is selected from hydroxylamines, ascorbic acids, and erythorbic acids. 5. The aqueous ballpoint pen according to claim 1 or 2, wherein the amount of movement of the ball in the longitudinal axis direction of the ballpoint pen tip is 15 nm or more and 45 μm or less.

Advantages of the Invention

[0008] The present invention provides an aqueous ballpoint pen that can provide a handwriting rich in shades like a fountain pen in an aqueous ballpoint pen, has no streaks or bleeding in the handwriting, and can further suppress bubbles in the aqueous ink.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the ballpoint pen of the present embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing an example of the ballpoint pen tip of the present embodiment.

Best Mode for Carrying Out the Invention

[0010] The feature of the present invention is an aqueous ballpoint pen having a ballpoint pen tip at the tip of an ink storage cylinder, and containing an ink composition for an aqueous ballpoint pen containing water, a colorant, a polyhydric alcohol, and a bubble absorbent in the ink storage cylinder, The ball diameter of the water-based ballpoint pen is 0.7 mm or more and 2.0 mm or less, When the ink consumption per 100 m of the water-based ballpoint pen is A (mg) and the ball diameter is B (mm), the relationship is 200 ≦ A / B ≦ 450, The ink viscosity of the ink composition for the water-based ballpoint pen is 40 mPa·s or less at 20°C and a shear rate of 384 sec -1 In this case, The water-based ballpoint pen is characterized in that the content of the polyhydric alcohol is 0.1% by mass or more and 10% by mass or less based on the total amount of the ink composition. The explanations of these components are as follows.

[0011] In the present invention, in order to make the handwriting of the water-based ballpoint pen rich in shades like that of a fountain pen and solve the problems of no streaks and no bleeding in the handwriting, when the ball diameter of the water-based ballpoint pen is 0.7 mm or more and 2.0 mm or less, When the ink consumption per 100 m is A (mg) and the ball diameter is B (mm), the relationship is 200 ≦ A / B ≦ 450, The ink viscosity of the ink composition for the water-based ballpoint pen is -1 Set to 40 mPa·s or less at 20°C and a shear rate of 384 sec, By setting the content of the polyhydric alcohol to 0.1% by mass or more and 10% by mass or less based on the total amount of the ink composition, it becomes possible to achieve the problems.

[0012] On the other hand, as described above, when the ink viscosity is set to a low viscosity and the ink consumption per 100 m is increased, air is likely to be entrapped (sucked in) from the tip of the ballpoint pen tip during writing, or air is entrapped during ink production, so bubbles tend to remain in the ink. Therefore, it is necessary to contain a bubble absorbent.

[0013] (Relationship between ink consumption per 100 m A (mg) and ball diameter B (mm)) In the present invention, if the ink consumption per 100m of a water-based ballpoint pen is A (mg) and the ball diameter is B (mm), then, considering that the writing of the water-based ballpoint pen can be varied in shade and intensity, like that of a fountain pen, unlike that of a normal ballpoint pen, and that the writing should not be smudged or blurred, it is necessary that the ratio of A / B be 200 ≤ A / B ≤ 450. More preferably, the ratio is 220 ≤ A / B ≤ 420, and more preferably 230 ≤ A / B ≤ 400. Furthermore, considering that the writing should be varied in shade and intensity, and that smudging and blurring should be suppressed, the ratio is 230 ≤ A / B ≤ 350. In particular, a ball diameter of 0.9 (mm) or more is preferable because it can produce writing that is varied in shade and intensity, and even more preferably 0.9 (mm) or more and 1.6 (mm) or less. In this invention, a spiral writing test is conducted using five test samples at a writing speed of 4 m / min on writing paper A conforming to the old JIS P3201, at a writing angle of 65° and a writing load of 100 g, at a writing speed of 4 m / min, at a temperature of 20°C. The average value of the ink consumption per 100 m from the initial writing stage (0 m to 100 m) is defined as the ink consumption per 100 m.

[0014] (Ink viscosity) Regarding ink viscosity, to achieve a rich, varied handwriting with varying shades, similar to that of a fountain pen, and to solve the problem of preventing smudging, the following conditions were met: under a temperature of 20°C, the shear rate was 384 seconds. -1 When writing, the ink viscosity should be 40 mPa·s or less. More preferably, the ink viscosity should be 30 mPa·s or less, and even more preferably 25 mPa·s or less if the goal is to create a varied handwriting with varying shades. Furthermore, within the above range, the writing feel and initial writing performance tend to improve, which is also preferable. On the other hand, considering the suppression of ink bleeding and leakage from the tip of the ballpoint pen, a shear rate of 384 sec in a 20°C environment is required. -1 The ink viscosity is preferably 5 mPa·s or higher, and more preferably 8 mPa·s or higher.

[0015] Also, at 20°C environment and a shear rate of 3.84 sec -1 (when stationary), the ink viscosity is preferably 200 mPa·s or more and 1000 mPa·s or less. This is because it is preferable for the ink to have good followability, making it easier to form a handwriting with rich light and shade variations, and furthermore, it is easier to suppress streaks and bleeding in the handwriting. More preferably, the ink viscosity is 200 mPa·s or more and 800 mPa·s or less, and even more preferably 250 mPa·s or more and 600 mPa·s or less.

[0016] Furthermore, considering forming a handwriting with rich light and shade variations like that of a fountain pen and suppressing streaks in the handwriting, it is preferable that the viscosity gradient of the ink composition during flow is a certain value or more, that is, the viscosity ratio of the ink composition at high shear and low shear is a certain value or more. Therefore, the viscosity ratio of the ink composition at high shear (during writing) and low shear (when stationary) (viscosity at a shear rate of 3.84 sec -1 / viscosity at a shear rate of 384 sec -1 is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. On the other hand, considering suppressing bleeding of the handwriting and ink leakage from the tip of the ball pen tip, the viscosity ratio of the ink composition at high shear (during writing) and low shear (when stationary) (viscosity at a shear rate of 3.84 sec -1 / viscosity at a shear rate of 384 sec -1 is preferably 60 or less, more preferably 50 or less, and even more preferably 40 or less.

[0017] (polyhydric alcohol) Furthermore, regarding the solvent, it is necessary to include a polyhydric alcohol, while considering solubility in water, to create a varied and nuanced handwriting similar to that of a fountain pen, suppressing smudging and bleeding of the ink, and ensuring that the polyhydric alcohol content is between 0.1% and 10% by mass of the total ink composition. This is because allowing the ink to slowly penetrate the paper surface makes it possible to create a varied and nuanced handwriting, and by controlling the ink's penetration and allowing it to gradually penetrate the paper surface, it is possible to create a handwriting with varying shades similar to that of a fountain pen.

[0018] Polyhydric alcohols are solvents in which two or more hydroxyl groups are bonded to opposite carbon atoms of an aliphatic or alicyclic compound. Specifically, examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, and glycerin. Among these, polyhydric alcohols having divalent or trivalent hydroxyl groups are preferred for creating ink lines with varying shades, such as those made with a fountain pen. More specifically, polyhydric alcohols having divalent hydroxyl groups are preferred, and ethylene glycol, diethylene glycol, and glycerin are preferred, with ethylene glycol and diethylene glycol being preferred. These may be used individually or in combination of two or more.

[0019] Regarding the polyhydric alcohol content, considering the ability to produce varied and nuanced handwriting and the stability of solubility in water, it is preferable that the content be between 0.1% and 8% by mass, preferably between 1% and 8% by mass, and more preferably between 3% and 7% by mass, based on the total amount of the ink composition.

[0020] (bubble absorbent) Examples of bubble absorbers include hydroxylamines, ascorbic acids, erythorbic acids, and polyphenols. These bubble absorbers are reducing compounds that absorb oxygen in the ink, thereby achieving a bubble-absorbing effect. Specifically, examples of hydroxylamines, ascorbic acids, erythorbic acids, and polyphenols include hydroxylamines, hydroxylamine derivatives, polyphenols, polyphenol derivatives, ascorbic acid, ascorbic acid derivatives, erythorbic acid, erythorbic acid derivatives, and their salts. Furthermore, considering the bubble-absorbing effect, it is preferable to select from among hydroxylamines, ascorbic acids, and erythorbic acids.

[0021] Regarding bubble absorbers, some ascorbic acids are highly acidic (pH value = 2) and can easily affect the ink's stability over time by reacting with components in the ink. Furthermore, ascorbic acids and polyphenols tend to affect the color tone, so it is preferable to use hydroxylamines or erythorbic acids. Also, since erythorbic acids may corrode ballpoint pen tips, it is preferable to use hydroxylamines. With regard to hydroxylamines, N,N-diethylhydroxylamine, N-methylhydroxylamine, N-(tert-butyl)hydroxylamine and / or their salts are preferred if the bubble absorption effect is given greater consideration, and N,N-diethylhydroxylamine is preferred if given greater consideration.

[0022] The content of the bubble absorbent is preferably 0.01% by mass or more and 2% by mass or less, relative to the total amount of the ink composition. This is because if it is 0.01% by mass or less, it is difficult to sufficiently absorb oxygen in the ink, and if it exceeds 2% by mass, it is likely to affect the ink's stability over time. More preferably, it is 0.1% by mass or more and 1% by mass or less, and even more preferably, it is 0.1% by mass or more and 0.5% by mass or less.

[0023] The colorants used in the aqueous ballpoint pen ink composition used in the present invention are not particularly limited and can be selected and used as appropriate, such as dyes and pigments. Dyes and pigments may be used in combination. Possible dyes include direct dyes, acid dyes, basic dyes, metal-containing dyes, and various salt-forming type dyes. These may be used individually or in combination of two or more.

[0024] Among colorants, it is preferable that the colorant contains a dye from the viewpoint of suppressing bubbles in the ink. This is because, although the reason is not entirely clear, it is expected that the inclusion of a dye will have an effect of suppressing bubble generation. Among dyes, it is preferable that the colorant contains a direct dye or an acid dye, considering the suppression of bubble generation, solubility with polyhydric alcohols, and color development. If further consideration is given, it is preferable that the colorant contains an acid dye, and if further consideration is given to suppressing bubble generation, a triphenylmethane-based acid dye is preferable. Furthermore, in order to easily obtain the characteristic handwriting and bubble-suppressing effect of the present invention, it is preferable to use a blue dye to create a blue water-based ballpoint pen ink composition.

[0025] The colorant content is preferably 4% by mass or less of the total ink composition, as this provides a bubble-suppressing effect. More preferably, it is 3% by mass or less, and even more preferably 2% by mass or less. Furthermore, from the viewpoint of bubble-suppressing effect, it is preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more.

[0026] When the content of the colorant in the total ink composition is X by mass and the content of the bubble absorber in the total ink composition is Y by mass, the relationship between X and Y is preferably 0.1 ≤ X / Y ≤ 40 if bubble suppression is considered more, preferably 0.2 ≤ X / Y ≤ 30 if further consideration is given, and even more preferably 0.5 ≤ X / Y ≤ 20.

[0027] Regarding dyes, various types are commercially available, and you can choose and use any of them as you like. (a) Direct dyes include Direct Black 17, 19, 22, 32, 38, 51, 71, 154, 168, 195; Direct Blue 1, 3, 15, 41, 71, 86, 87, 106, 119; Direct Yellow 4, 26, 44, 50, 85; Direct Red 1, 2, 4, 23, 31, 37, 39, 75, 80, 81 (b) Acid dyes include Acid Black 1, 2, 24, 26, 31, 52, 107, Acid Orange 56, Acid Yellow 3, 7, 17, 19, 23, 42, 49, 61, 92, Acid Red 8, 9, 14, 18, 51, 52, 73, 87, 92, 94, 28 (c) Basic dyes include CI Basic Yellow-1, CI Basic Yellow-2

[0028] Pigments include inorganic, organic, and processed pigments, but specifically include carbon black, aniline black, ultramarine, lead yellow, titanium dioxide, iron oxide, phthalocyanine, azo, quinacridone, diketopyrrolopyrrole, quinophthalone, surene, triphenylmethane, perinone, perylene, dioxazine, metallic pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, and microcapsule pigments.

[0029] (Surfactants) In this invention, it is preferable to include a surfactant in order to improve lubricity, suppress wear of the ball seat, and improve writing feel. Examples of the surfactant include silicone-based surfactants, fluorine-based surfactants, phosphate ester-based surfactants, and fatty acids. Among these, it is preferable to include a phosphate ester-based surfactant or a fatty acid. This is because those having phosphate groups or fatty acid groups have adsorption capacity to metals and, by adsorbing to the ball and tip body, provide a lubricating effect, resulting in good ink ejection, a rich and varied writing style with varying shades, and preventing smudging.

[0030] Examples of phosphate ester surfactants include styrene-phenol, nonylphenol, lauryl alcohol, tridecyl alcohol, octylphenol, and short-chain alcohol types. Among these, it is preferable to use short-chain alcohol types such as lauryl alcohol and tridecyl alcohol, as they result in good ink ejection, a rich and varied line with varying shades, and no smudging. Tridecyl alcohol is preferred. These may be used individually or in combination of two or more types.

[0031] Furthermore, considering the need to improve lubricity, ensure good ink ejection, produce varied and nuanced handwriting, and prevent smudging, the acid value of the phosphate ester surfactant is preferably 170 mgKOH / g or less, more preferably 120 mgKOH / g or less, and even more preferably 100 mgKOH / g or less. Furthermore, considering stability in the ink and lubricity, the acid value is preferably 50 mgKOH / g to 170 mgKOH / g, preferably 70 mgKOH / g to 170 mgKOH / g, and more preferably 80 mgKOH / g to 120 mgKOH / g.

[0032] Furthermore, examples of fatty acids include lauric acid, myristic acid, stearic acid, oleic acid, ricinoleic acid, linoleic acid, and their alkali metal salts, ammonium salts, and amine salts. Fatty acids preferably have 12 to 24 carbon atoms. This is because, within this range, the lubricity of the ball is easily improved, resulting in good ink ejection, creating varied and richly colored lines without smudging. More specifically, fatty acids with 16 to 20 carbon atoms are preferable.

[0033] The amount of the surfactant is preferably 3% by mass or less, and more preferably 2% by mass or less, and more preferably 1% by mass or less, relative to the total amount of the ink composition, considering the need to produce varied handwriting with varying shades and suppress ink bleeding. This is because allowing the ink to slowly penetrate the paper surface makes it possible to produce varied handwriting with varying shades, and by controlling the ink's permeability so that it gradually penetrates the paper surface, it is possible to produce handwriting with varying shades, similar to that of a fountain pen. On the other hand, to easily achieve the desired suppression of ball seat wear and improvement of writing feel, a value of 0.1% by mass or more is preferable, and if given more consideration, 0.3% by mass or more is preferable.

[0034] Furthermore, it is preferable that the ink viscosity modifier includes a shear viscosity modifier. Examples of shear viscosity modifiers include crosslinked acrylic acid polymers and polysaccharides such as xanthan gum, gellan gum, succinoglycan, guar gum, locust bean gum, λ-carrageenan, cellulose derivatives, and dieutan gum. Examples of associated thickeners include polyester-based, polyether-based, urethane-modified polyether-based, and polyaminoplast-based thickeners depending on the associated hydrophobic group, as well as alkali-swelling associated thickeners and nonionic associated thickeners. These shear viscosity modifiers may be used individually or in combination of two or more types.

[0035] Among shear viscosity reducing agents, the ink viscosity of a water-based ballpoint pen ink composition was reduced at 20°C and a shear rate of 384 sec. -1In this regard, it is preferable to use polysaccharides because it is easy to set the pressure to 40 mPa·s or less, and it is preferable to use polysaccharides because it is easy to produce a rich, varied handwriting with varying shades, like that of a fountain pen, and it is easier to suppress smudging and bleeding in the handwriting. Among polysaccharides, xanthan gum and succinoglycan are preferred, and if given further consideration, succinoglycan is preferable.

[0036] Furthermore, regarding the content of the shear viscosity reducing agent, in order to easily obtain the above-mentioned effects, it is more preferable that the content be 0.01% by mass or more and 2% by mass or less, with respect to the total amount of the ink composition, more preferably 0.1% by mass or more and 1% by mass or less, with respect to respect to 0.1% by mass or more and 0.5% by mass or less, and even more preferably 0.1% by mass or more and 0.4% by mass or less.

[0037] Furthermore, considering the inclusion (swallowing) of air from the tip of the ballpoint pen after writing, it is preferable that the ink contains dextrin. This is because the film formed by dextrin makes it easier to suppress the inclusion (swallowing) of air from the tip of the ballpoint pen, and thus easier to suppress the mixing of air bubbles into the ink. Furthermore, as in the present invention, when the polyhydric alcohol content is kept to a small amount, such as 0.1% by mass or more and 10% by mass or less, it is likely to affect moisturizing properties and thus the writing performance. Therefore, dextrin is preferable because it has the effect of easily improving the writing performance. This is because the film formed when the tip of the ballpoint pen dries does not become too hard, skipping at the start of writing is suppressed, and the formed film suppresses the evaporation of solvents in the composition, thereby preventing the film on the tip of the ballpoint pen from becoming excessively hard.

[0038] Furthermore, examples of starches used as raw materials for dextrin include cornstarch (dent cornstarch), waxy cornstarch, sweet potato starch, potato starch, tapioca (cassava starch), wheat starch, and rice starch (glutinous rice starch and non-glutinous rice starch). As a raw material for dextrin, waxy cornstarch and sweet potato starch are preferred when considering the suppression of air entrainment (swallowing) from the tip of the ballpoint pen and the effect on writing performance.

[0039] Furthermore, regarding the dextrose equivalent (DE) of the dextrin, considering that it is easier to suppress air entrapment (swallowing) from the tip of the ballpoint pen and that it is easily soluble and stable in the ink, it is preferable that the dextrin has a dextrose equivalent (DE) of 2 to 25. Moreover, considering the suppression of air entrapment (swallowing) from the tip of the ballpoint pen and the effect on writing performance, it is preferable that the dextrose equivalent (DE) is 2 to 15, and if given even greater consideration, it is preferable that it is 2 to 8. Dextrose equivalent is an index that indicates the degree of decomposition when starch is broken down by acid or enzyme, and is known as a relative scale when the reducing power of dextrose (glucose) is set to 100. In this specification, dextrose equivalent will be abbreviated as "DE" (Dextrose equivalent). A DE of 0 indicates starch, and the closer to 0, the closer the material is to starch. Conversely, the closer the DE is to 100, the more advanced the hydrolysis of the starch is. The DE of dextrin can be measured using the Somogyi-Nelson method. In addition, if the manufacturer's guaranteed value or measured value of the DE of dextrin is known, for example, that value can be adopted as the DE value of the dextrin.

[0040] The dextrin content is preferably 0.1% by mass or more and 5% by mass or less of the total ink composition. This is because if it is less than 0.1% by mass, it is difficult to sufficiently suppress air entrapment (swallowing) from the tip of the ballpoint pen and improve writing performance, and if it exceeds 5% by mass, it is difficult to dissolve in the ink. Considering this further, 0.3% by mass or more and 4% by mass or less is preferable, and if considering the suppression of air entrapment (swallowing) from the tip of the ballpoint pen and the effect on writing performance even more, 0.5% by mass or more and 3% by mass or less is preferable.

[0041] Furthermore, as in the present invention, when the polyhydric alcohol content is kept to a small amount, such as 0.1% by mass or more and 10% by mass or less, it is likely to affect moisture retention and thus writing performance. Therefore, it is preferable to include urea, which has a hygroscopic effect. This is because, when the ink at the tip of the ballpoint pen dries, the solidification of the film formed by dextrin is mitigated, resulting in a greater improvement in writing performance. For this reason, in the present invention, it is preferable to use dextrin and urea in combination.

[0042] Furthermore, the urea content is preferably 0.1% by mass or more and 10% by mass or less of the total amount of ink composition. This is because if it falls outside this range, the effect of the writing performance tends not to be sufficiently obtained. Taking this tendency into consideration, 0.1% by mass or more and 5% by mass or less is preferable, and most preferably 1.0% by mass or more and 3.0% by mass or less.

[0043] pH adjusters are used to adjust pH, neutralize surfactants, and prevent corrosion of metal parts that come into contact with water-based inks. Examples of pH adjusters include basic inorganic compounds such as ammonia, sodium carbonate, sodium phosphate, and sodium hydroxide; basic organic compounds such as sodium acetate, triethanolamine, and diethanolamine; lactic acid; and citric acid. Of these, basic organic compounds are preferred, and triethanolamine, which is weakly basic, is preferred.

[0044] Examples of preservatives and rust inhibitors include phenol, sodium benzoate, potassium sorbate, propyl parahydroxybenzoate, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, sodium 2-pyridinethiol-1-oxide, 1,2-benzoisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitride, diisopropylammonium nitride, sodium thiosulfate, saponin, or dialkylthiourea.

[0045] Other additives may be included as desired. Specifically, fixatives such as acrylic resin emulsions, urethane resin emulsions, and styrene-butadiene resin emulsions, resin particles such as olefin resin particles and nitrogen-containing resin particles, humectants such as sorbitol, and chelating agents such as ethylenediaminetetraacetic acid may be added. These can be used individually or in combination of two or more.

[0046] Furthermore, the surface tension of the ink composition of the present invention at 20°C is preferably 20 mN / m or more and 55 mN / m or less. If the surface tension of the ink composition is within the above numerical range, it is easier to produce handwriting with varying shades, and more preferably 25 mN / m or more and 45 mN / m or less, and particularly preferably 27 mN / m or more and 40 mN / m or less. The surface tension is determined by measuring it using a platinum plate and the vertical plate method at a 20°C environment using a surface tension meter (DY-200) manufactured by Kyowa Interface Science Co., Ltd.

[0047] Furthermore, the pH value of the water-based ballpoint pen ink composition is preferably between 7 and 11. This is because if the pH value is below 7 and in the acidic range, it will affect the stability of the ink components and cause corrosion of the metal ballpoint pen tip and ball. Similarly, if the pH value exceeds 11 and is strongly alkaline, it will also affect the stability of the ink components. Considering this further, a pH value between 7 and 10 is even more preferable.

[0048] (Ballpoint pen tip) Furthermore, the amount of movement (clearance) of the ball in the vertical axis direction of the ballpoint pen tip used in the present invention is preferably 15 μm or more and 45 μm or less. This is because if it is less than 15 μm, it is difficult to set the relationship 200 ≤ A / B ≤ 450 as described above, making it difficult to create a rich and varied handwriting with varying shades, like a fountain pen, and making it difficult to suppress smudging and bleeding in the handwriting. If it exceeds 45 μm, it is more likely to affect the suppression of bleeding and ink leakage. Considering this further, it is preferable to set it to 20 μm or more and 40 μm or less, and if considering this even further, it is preferable to set it to 20 μm or more and 35 μm or less. The amount of movement (clearance) of the ball in the vertical axis direction of a ballpoint pen tip refers to the distance the ball can move along the vertical axis direction of the ballpoint pen tip body.

[0049] In order to produce a rich and varied writing style with varying shades, similar to that of a fountain pen, and to ensure that the writing is free from smudging and bleeding, and to improve the suppression of air entrainment from the tip of the ballpoint pen, thereby maintaining good writing performance, it is preferable to have a valve mechanism that presses a ball, which is rotatably held at the tip of the ballpoint pen, against the inner wall of the tip edge either directly or via a pressing body using an elastic member such as a coil spring, thereby creating a gap between the inner wall of the tip edge and the ball due to the pressure applied during writing, allowing ink to flow out, and to close even the minute gap at the tip of the pen when not in use. In particular, when a shear viscosity reducing agent is used, when a load is applied to the ball during writing, the elastic member inside the ballpoint pen tip vibrates, applying a shear force to the ink inside the tip. This reduces the ink viscosity, improving the writing feel and further enhancing ink ejection, resulting in a rich and varied writing style with varying shades, which is preferable. Furthermore, using an elastic member such as a coil spring to close the minute gap at the tip when not in use improves air entrainment from the tip of the ballpoint pen, which is also preferable. Furthermore, it is preferable to use resilient materials such as coil springs and rubber, and considering resilience and durability, it is preferable to use coil springs.

[0050] When using elastic members such as coil springs, if the goal is to produce a varied handwriting with varying shades, similar to that of a fountain pen, and to avoid smudging or bleeding, then the viscosity ratio of the ink composition at high shear (writing) and low shear (stationary) (viscosity at a shear rate of 3.84 sec⁻¹ / viscosity at a shear rate of 384 sec⁻¹) is preferably between 10 and 60, preferably between 15 and 50, and more preferably between 20 and 40.

[0051] Furthermore, while there are no particular limitations on the materials used for the balls, examples include cemented carbide balls with tungsten carbide as the main component, metal balls such as stainless steel, ceramic balls such as silicon carbide, silicon nitride, alumina, silica, and zirconia, and ruby ​​balls.

[0052] Furthermore, in order to produce a varied handwriting with varying shades and to avoid smudging, it is preferable that the arithmetic mean roughness (Ra) of the ball surface be between 0.1 nm and 5 nm. This is because, although the reason is unclear, if the arithmetic mean roughness (Ra) falls outside this range, the ink does not adhere sufficiently to the ball surface, making it difficult to obtain the desired handwriting. More specifically, it is preferable that the arithmetic mean roughness (Ra) of the ball surface be between 0.1 nm and 4 nm, and more preferably between 0.5 nm and 3 nm.

[0053] The arithmetic mean roughness of the ball surface is calculated by taking a sample of the roughness curve measured by a surface roughness measuring instrument (model name SPI3800N, manufactured by Seiko Epson), extracting a reference length in the direction of the mean line, summing the absolute values ​​of the deviations from the mean line to the measurement curve for this sampled portion, and then averaging the result.

[0054] Furthermore, it is preferable that the crimping angle of the ballpoint pen tip be between 50 and 90 degrees. Within this range, it is possible to maintain sufficient space for ink to accumulate between the ball 9 and the tip edge, ensuring a stable ink output, resulting in varied and nuanced handwriting, and making it easier to suppress smudging. Moreover, considering the above, it is preferable that the crimping angle be between 65 and 85 degrees.

[0055] When ink is directly contained in the ink container, it is preferable to fill the rear end of the ink with an ink backflow prevention body. The ink backflow prevention body consists of a non-volatile liquid or a low-volatility liquid. Specifically, examples include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, fatty acid-modified silicone oil, etc., and one or more of these can be used in combination. As in the present invention, while maintaining the relationship 200 ≤ A / B ≤ 450, the ink viscosity is such that at 20°C and a shear rate of 384 sec -1 In this case, even when the pressure is 40 mPa·s or less, if the goal is to produce a varied handwriting with varying shades and to prevent smudging or bleeding of the handwriting, it is preferable that the mixture contains at least polybutene.

[0056] The non-volatile liquid and / or non-volatile liquid is preferably thickened to a suitable viscosity by adding a thickening agent. Examples of the thickening agent include silica with a hydrophobic surface treatment, fine particle silica with a methylated surface treatment, aluminum silicate, swellable mica, clay-based thickening agents such as hydrophobic treated bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, tripenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, dextrin compounds such as fatty acid dextrins, and cellulose compounds. Furthermore, the liquid ink backflow prevention body and the solid ink backflow prevention body can be used in combination.

[0057] The present invention will now be explained with reference to examples. Example 1 Dye (triphenylmethane-based acid dye) 2.0 parts by mass Water 87.5 parts by mass Polyhydric alcohol (diethylene glycol) 5.0 parts by mass Bubble absorbent (hydroxylamines) 0.3 parts by mass Phosphate ester surfactant (acid value: 87 (mgKOH / g)) 0.5 parts by mass Dextrin (derived from waxy corn starch, DE: 6 to 8) 1.0 part by mass pH adjuster (triethanolamine) 2.0 parts by mass Phosphate ester surfactant 0.5 parts by mass Urea 1.0 parts by mass Rust inhibitor (benzotriazole) 0.5 parts by mass Shear viscosity reducing agent (succinoglycan) 0.20 parts by mass

[0058] The blue water-based ballpoint pen ink composition of Example 1 was prepared by heating and stirring the ink components other than the shear viscosity reducing agent using a magnetic hot stirrer to create a base ink.

[0059] Subsequently, the base ink prepared above was heated, a shear viscosity reducing agent was added, and the mixture was thoroughly mixed and stirred using a homogenizer stirrer until it became uniform, thereby obtaining the blue aqueous ballpoint pen ink composition of Example 1. The ink viscosity of Example 1 was measured using a Brookfield DV-II+Pro viscometer (CPE-42 rotor) at 20°C with a shear rate of 384 sec. -1 (Rotation speed 100 rpm) and shear rate 3.84 sec -1 When the ink viscosity was measured under the condition of a rotation speed of 1 rpm, it was found to be 16 mPa·s and 455 mPa·s, respectively. Viscosity ratio of ink composition under high shear (writing) and low shear (static) conditions (shear rate 3.84 sec -1 Viscosity / shear rate at 384 sec -1 The viscosity (at this point) was 28. Furthermore, the surface tension of Example 1 was measured using a surface tension measuring instrument DY-200 (at 20°C, using a platinum plate and the vertical plate method, manufactured by Kyowa Interface Science Co., Ltd.) and was found to be 32.9 mN / m. Furthermore, using an HM-30R pH meter (manufactured by Toa DKK Co., Ltd.), the pH of the ink composition was measured at 20°C, and the result was 8.5.

[0060] Examples 2-21, Comparative Examples 1-5 Except for changing the ink components and tip specifications as shown in the table, the blue water-based ballpoint pen ink compositions and water-based ballpoint pen refills of Examples 2 to 21 were obtained using the same procedure as in Example 1. The evaluation results are shown in the table. [Table 1] [Table 2] [Table 3]

[0061] Testing and evaluation The blue aqueous ballpoint pen ink compositions prepared in the examples and comparative examples were filled into an ink reservoir 2 (made of polypropylene) equipped with a ballpoint pen tip 4, which rotatably holds a 1.0 mm diameter ball 11 at the tip of the ink reservoir 2, and a ballpoint pen tip 4 is filled into an ink reservoir 2 (made of polypropylene) via a tip holder 3 (which has a coil spring that directly presses the ball inside the tip against the inner wall of the tip edge, the ball's vertical axial movement is 30 μm, and the arithmetic mean roughness (Ra) of the ball surface is 1 nm). An ink backflow prevention body 7 (containing polyplyden) was filled into the rear end of the ink. The following tests and evaluations were performed by attaching the refill (1.0 g) to a cap-type gel ink ballpoint pen 1 (product name: G-1) manufactured by Pilot Corporation. The following tests and evaluations were performed. For the evaluation of the ink density test, ink smudging / bleeding test, and bubble generation test, writing paper A conforming to the old JIS P3201 was used as the writing test paper, and the evaluation was performed using the following test methods. Furthermore, a spiral writing test was conducted using the water-based ballpoint pen of Example 1. When the ink consumption per 100m was A (mg) and the ball diameter was B (mm), the results were A = 290 (mg), B = 1.08 (mm), and A / B = 290.

[0062] Specifically, the ballpoint pen tip 4 is made by cutting a φ2.5 mm stainless steel wire to the desired length, creating a ball-holding chamber 13, an ink flow hole 14, and ink flow grooves 15 that radiate from the ink flow hole 14, and then forming a ball seat 16 on the bottom wall of the ball-holding chamber 13. After that, a cemented carbide ball 11 is placed on the ball seat 16, and the tip portion 12 is crimped inward.

[0063] Furthermore, the ball protrusion H from the tip of the chip when the ball 11 is placed on the ball seat 16 is set to be 30.0% of the ball diameter, the crimping angle α is set to be 75 degrees, and the amount of movement L of the ball 11 in the vertical axis direction is set to be 30 μm.

[0064] Measurement results for ink viscosity, surface tension, and pH. The ink viscosity of Examples 5, 6, 13, and 19 was measured using a Brookfield DV-II+Pro viscometer (CPE-42 rotor) at 20°C with a shear rate of 384 sec. -1(Rotation speed 100 rpm) and shear rate 3.84 sec -1 The ink viscosity was measured under the condition of a rotation speed of 1 rpm, and the viscosity ratio was calculated. Example 5: 17 mPa·s, 480 mPa·s, viscosity ratio 28 Example 6: 17 mPa·s, 473 mPa·s, viscosity ratio 28 Example 13: 16 mPa·s, 460 mPa·s, viscosity ratio 29 Example 19: 14 mPa·s, 602 mPa·s, viscosity ratio 43 Furthermore, the surface tension of Examples 5, 6, 13, and 19 was measured using a surface tension meter DY-200 (at 20°C, using a platinum plate and the vertical plate method, manufactured by Kyowa Interface Science Co., Ltd.). Example 5: 30.8 mN / m Example 6: 32.1 mN / m Example 13: 31.5 mN / m Example 19: 31.0 mN / m That was the case. Furthermore, the pH of the ink compositions in Examples 5, 6, 13, and 19 was measured at 20°C using an HM-30R pH meter (manufactured by Toa DKK Co., Ltd.). Example 5: 8.7 Example 6: 8.7 Example 13: 8.7 Example 19: 8.7

[0065] Handwriting density test: The handwriting was visually observed after writing. ◎...There were many variations in handwriting with varying shades. ○...Handwriting with varying shades and textures. ×...There was almost no variation in handwriting with varying shades.

[0066] Handwriting smudging and bleeding test: The handwritten text was visually observed after writing. ◎...The handwriting should be free from smudging or bleeding. ○...Some items may have slight smudging or bleeding in the handwriting. ×...The handwriting is smudged or blurred, making it unsuitable for practical use.

[0067] Bubble formation test: A ballpoint pen was placed upside down and left in a 50°C environment for one month, after which the number of bubbles was observed. ◎···No air bubbles ○...Some products have produced a small amount of bubbles. ×...A large number of air bubbles were generated, and as the bubbles grew, a gap was created between the ink backflow prevention element and the ink.

[0068] As shown in the table, Examples 1-21 showed good performance in all tests, including ink density test, ink smudging / bleeding test, and bubble formation test. However, in Example 7, erythorbic acid was used as the bubble absorber, resulting in corrosion of the ballpoint pen tip, and the writing quality was slightly inferior compared to Examples 1-6.

[0069] As shown in the table, Comparative Example 1 performed poorly in the bubble generation test because no bubble absorbent was used. In comparative examples 2 and 3, the high polyhydric alcohol content resulted in almost no variation in shading in the handwriting. In Comparative Example 4, the amount of ink consumed was not appropriate, resulting in almost no variation in shading in the handwriting and smudging. In Comparative Example 5, the amount of ink consumed was not appropriate, resulting in smudging of the handwriting.

[0070] The water-based ballpoint pen according to the present invention is effective because, by providing a cap that covers the tip of the ballpoint pen, it is possible to suppress air entrapment from the tip of the ballpoint pen, further suppress ink leakage from the tip of the ballpoint pen, and improve writing performance. Furthermore, the form of the writing instrument according to the present invention is not limited to the configuration described above, but may also be a compound writing instrument (double-ended writing instrument) with different shaped tips attached.

[0071] Furthermore, while Examples 1, 6, and 21 are all blue water-based ballpoint pen ink compositions, Example 6 is a reddish-blue ink, and Example 21 is a blackish-blue ink, thus creating blue inks with different shades. Furthermore, these ballpoint pen refills or ballpoint pens containing different shades of blue ink may be displayed and sold as a group of ballpoint pen refills or ballpoint pens, or the ballpoint pen refills or ballpoint pens may be placed in a case to create a ballpoint pen set.

[0072] Furthermore, in this invention, since users can enjoy writing by flexibly using different shades of blue ink depending on the application each time, it is preferable to have a group of ballpoint pen refills or ballpoint pens containing different shades of blue ink, and it is even more preferable to have a blue ballpoint pen set in which ballpoint pen refills or ballpoint pens containing different shades of blue ink are housed in a case. In the examples, blue inks of different shades were used as examples, but chromatic colors such as yellow, red, and green inks may be used, as well as achromatic colors such as black and white. However, chromatic colors are preferable because they result in more vivid colors.

[0073] Furthermore, in ballpoint pen refills or ballpoint pens containing blue inks of different shades, such as in Examples 1, 6, and 21, the appearance will be similar in color. Therefore, to prevent mixing during production and product misidentification, it is preferable to have identification members with different color shades on each ballpoint pen component, such as the barrel, cap, end cap, tip holder, and grip of each ballpoint pen refill or ballpoint pen. For example, in Example 1, at least one of the ballpoint pen components such as the blue barrel, ink reservoir, cap, end plug, tip holder, or grip has a blue identification component; in Example 6 (reddish-blue ink), at least one of the ballpoint pen components such as the red barrel, ink reservoir, cap, end plug, tip holder, or grip has a red identification component; and in Example 21 (blackish-blue ink), at least one of the ballpoint pen components such as the black barrel, ink reservoir, cap, end plug, tip holder, or grip has a black identification component. This makes it possible to prevent mixing during production and product misidentification even if there are ballpoint pen refills or ballpoint pens containing ink colors of similar shades.

[0074] In this invention, as shown in the examples, a refill containing an aqueous ballpoint pen ink composition in an ink reservoir is attached to the barrel and used as a ballpoint pen. However, the invention is not limited to this form, and the ink reservoir may be used as the barrel and filled with the aqueous ballpoint pen ink composition to use as a ballpoint pen as is. [Industrial applicability]

[0075] The present invention can be used as a water-based ballpoint pen, and more specifically, it can be widely used as a water-based ballpoint pen with a cap, retractable pen, etc.

[0076] 1 Ballpoint pen refill 2 ink cartridges 3 Chip holder 4 ballpoint pen tips 5. Tail plug 6. Ink composition for oil-based ballpoint pens 7. Ink backflow prevention element 11 balls 12 Tip end 13 Ball Holding Room 14 Ink flow holes 15 Ink flow groove 16 Ball Seat H Ball L-ball's vertical axis displacement α Crimping angle

Claims

1. A water-based ballpoint pen having a ballpoint pen tip at the front of an ink reservoir, and containing a water-based ballpoint pen ink composition comprising water, a colorant, a polyhydric alcohol, and a bubble absorbent in the ink reservoir, The ball diameter of the water-based ballpoint pen is 0.7 mm or more and 2.0 mm or less. If the ink consumption per 100m of a water-based ballpoint pen is A (mg) and the ball diameter is B (mm), then the relationship is 200 ≤ A / B ≤ 450. The ink viscosity of the water-based ballpoint pen ink composition is 384 sec at 20°C. －１ In this case, the pressure is 40 mPa·s or less. A water-based ballpoint pen characterized in that the polyhydric alcohol content is 0.1% by mass or more and 10% by mass or less of the total amount of the ink composition.

2. The aqueous ballpoint pen according to claim 1, wherein the aqueous ballpoint pen ink composition contains a phosphate ester surfactant or a fatty acid, and the amount of the surfactant is 0.1% by mass or more and 3% by mass or less with respect to the total amount of the ink composition.

3. The water-based ballpoint pen according to claim 1 or 2, characterized in that the coloring agent is a dye, and the content of the dye is 0.1% by mass or more and 4% by mass or less with respect to the total amount of the ink composition.

4. The water-based ballpoint pen according to claim 1 or 2, characterized in that the foam inhibitor is selected from hydroxylamines, ascorbic acids, and erythorbic acids.

5. The aqueous ballpoint pen according to claim 1 or 2, characterized in that the amount of movement of the ball of the ballpoint pen tip in the longitudinal axis direction is 15 nm or more and 45 μm or less.

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