JP6833436B2 - Water-based ink composition for ballpoint pens and ballpoint pens containing them - Google Patents

Description

The present invention relates to a water-based ink composition for a ballpoint pen. Furthermore, the present invention relates to a water-based ink composition for a ballpoint pen using titanium oxide.

Conventionally, titanium oxide has been used to form a hue of white or pastel color, and when it is used as an ink for ballpoint pens, a shear thinning agent is also used to ensure dispersion stability when not in use. As a result, aggregation and sedimentation in the ink are suppressed.
Further, in addition to the above configuration, a technique of using a phosphoric acid ester type surfactant in combination has been proposed for the purpose of suppressing metal wear due to titanium oxide and improving lubricity at the time of writing (for example, Patent Document 1). reference).

Japanese Unexamined Patent Publication No. 10-330678

With water-based ink for ballpoint pens that uses titanium oxide, when the ink is ejected during writing, the tip is worn by the titanium oxide polishing the ball surface and ball seat, causing line skipping and blurring in the handwriting, and writing is impossible. However, since the wear due to the above-mentioned polishing is suppressed by using the phosphoric acid ester type surfactant in combination, a good handwriting and a smooth writing feeling can be obtained.

However, when the ink using titanium oxide is built in the ink storage cylinder, it adheres to the inner wall of the ink storage cylinder when moving forward along with the ink consumption by writing, which hinders the ink consumption or the ink. With a transparent material in which the inside of the storage cylinder can be visually recognized, problems such as the remaining amount of ink not being able to be confirmed and the appearance being impaired have occurred.

According to the present invention, even with a water-based ink for a ballpoint pen using titanium oxide, not only good handwriting and a smooth writing feeling can be obtained without causing metal wear of the tip, but also ink can be stored when moving due to ink consumption. It is an object of the present invention to provide a highly practical water-based ink composition for a ballpoint pen, which can surely suppress adhesion to the inner wall of a cylinder, and a ballpoint pen incorporating the composition.

The present invention is an aqueous ink composition containing at least titanium oxide, a phosphoric acid ester, a shear- degrading agent, and water, wherein the titanium oxide has an oil absorption amount of 12 to 25 ml / 100 g and is a phosphoric acid ester. A water-based ink composition for a ballpoint pen having an HLB value in the range of 14 to 20 is a requirement.
Further, the viscosity at 1 rpm by the rotational viscometer is in the range of 1000 to 2500 mPa · s (20 ° C.), and the titanium oxide is added in the range of 0.1 to 20% by weight in the total amount of the ink composition. It is required that the phosphoric acid ester is added in the range of 0.01 to 10% by weight based on the total amount of the ink composition, and that the shear thinning agent is succinoglycan.
Further, the water-based ink composition for a ballpoint pen according to any one of the above requires a ballpoint pen built in a transparent ink storage cylinder, the inner diameter of the ink storage cylinder is 4 mm or less, and the ink storage cylinder It is required that the material is polypropylene resin.

According to the present invention, even with a water-based ink using titanium oxide, not only good writing and smooth writing feeling can be obtained without causing metal wear of the chip, but also when moving due to ink consumption, the inner wall of the ink containing cylinder A water-based ink composition for ballpoint pens with excellent practicality that does not hinder ink consumption, make it impossible to check the remaining amount of ink, or spoil the appearance because it can suppress adhesion. It becomes a built-in ballpoint pen.

The present invention has been diligently studied to eliminate ink adhesion to the inner wall of an ink containing cylinder in an aqueous ink composition containing at least titanium oxide, a phosphoric acid ester, a shear-degrading agent and water, and as a result, the oil absorption of titanium oxide It was discovered that the amount and the HLB value of the phosphate ester contributed, and the best conditions were found.

The oil absorption of the titanium oxide is measured by a test method specified in JIS. That is, the value measured by the method specified in JIS K 5101 is used as the oil absorption amount.
In the present invention, by selecting titanium oxide having an oil absorption amount of 10 ml / 100 g to 30 ml / 100 g, it acts with the phosphoric acid ester having the specific HLB value to suppress ink adhesion to the inner wall of the ink containing cylinder, and at the time of writing. Ink followability is high. If the oil absorption amount is less than 10 ml / 100 g, the dispersibility in the water medium is low, and if the oil absorption amount exceeds 30 ml / 100 g, the effect is low, so the above range is useful.
Further, since the titanium oxide having an oil absorption amount has high weather resistance, yellowing and browning of the handwriting with time are unlikely to occur, and a handwriting having excellent hue stability can be formed. In particular, those having an oil absorption amount of 12 ml / 100 g to 25 ml / 100 g have the above-mentioned effects and are more useful.

Specifically, as titanium oxide that can be used, Titone SR-1 (oil absorption amount 19 to 21), R-650 (oil absorption amount 20 to 22), R-3L (oil absorption amount 21 to 24), R-5N. (19-21) [above, manufactured by Sakai Chemical Industry Co., Ltd.], Typake R-580 (oil absorption amount 19), R-550 (oil absorption amount 23), R-690 (oil absorption amount 16), R- 691 (oil absorption amount 15), R-711 (oil absorption amount 19), R-736 (oil absorption amount 15), R-739 (oil absorption amount 14), R-930 (oil absorption amount 19), A- 100 (oil absorption amount 22), A-220 (oil absorption amount 21), CR-50 (oil absorption amount 18), CR-50-2 (oil absorption amount 17), CR-58 (oil absorption amount 19), same CR-60-2 (oil absorption 14), CR-63 (oil absorption 14), CR-Super70 (oil absorption 16), CR-85 (oil absorption 30) [above, manufactured by Ishihara Sangyo Co., Ltd.] , Kronos KR-310 (oil absorption 17-22), KR-380 (oil absorption 19-24), KR-480 (oil absorption 19-24) [above, manufactured by Titanium Industry Co., Ltd.], Typure R- 900 (oil absorption 14), R-902 (oil absorption 17) [above, manufactured by DuPont Japan Limited], Titanics JR-300 (oil absorption 18), JR-301 (oil absorption 18), same Examples thereof include JR-600A (oil absorption amount 18), JR-701 (oil absorption amount 20), JR-800 (oil absorption amount 29) [above, manufactured by Teika Co., Ltd.] and the like.
The titanium oxide functions as a colorant when used in the range of 0.1 to 20% by weight, more preferably 1 to 15% by weight, based on the total amount of the ink composition.

Further, by using a general-purpose coloring material together with the titanium oxide, a chromatic ink such as pastel color can be formed, and as the coloring material, dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used. Specific examples are shown below.
As the dye, acid dyes, basic dyes, direct dyes and the like can be used.
Acid dyes include ponceau (CI 16255), tartrazine (CI 19140), acid blue black 10B (CI 20470), guinea green (CI 42085), brilliant blue FCF. (CI 42090), Acid Violet 6B (CI 42640), Solve Blue (CI 42755), Naphthalene Green (CI 44025), Eosin (CI 45380), Phloxine (CI 45410), erythrosine (CI 45430), niglosin (CI 50420), acid phloxine (CI 56205) and the like are used.
As basic dyes, chrysoidin (CI 11270), methyl violet FN (CI 42535), crystal violet (CI 42555), malachite green (CI 42000), Victoria blue FB ( CI 44045), Rhodamine B (CI 45170), Acridine Orange NS (CI 46005), Methylene Blue B (CI 52015) and the like are used.
As direct dyes, Congo Red (CI 22120), Direct Sky Blue 5B (CI 24400), Violet BB (CI 27905), Direct Deep Black EX (CI 30235), Kaya Las Black G Conc (CI 35225), Direct Fast Black G (CI 35255), Phthalocyanine Blue (CI 74180) and the like are used.

The pigments include inorganic pigments such as carbon black and ultramarine blue, organic pigments such as copper phthalocyanine blue and benzidine yellow, and water-dispersed pigments finely and stably dispersed in an aqueous medium using a surfactant or the like in advance. Products and the like are used, for example, C.I. I. Pigment Blue 15: 3B [Product name: S.I. S. Blue GLL, pigment content 22%, manufactured by Sanyo Dye Co., Ltd.], C.I. I. Pigment Red 146 [Product name: S.I. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Dye Co., Ltd.], C.I. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content about 30%, manufactured by Dainichiseika Kogyo Co., Ltd.], C.I. I. Pigment Red 220/166 [Product name: TC Red FG, pigment content of about 35%, manufactured by Dainichiseika Kogyo Co., Ltd.] and the like can be mentioned.
As the fluorescent pigment, a synthetic resin fine particle fluorescent pigment in which various fluorescent dyes are solid-solved in a resin matrix can be used.
In addition, pearl pigments, gold and silver metallic pigments, phosphorescent pigments, metal powders such as aluminum, and heat-discoloring compositions, photo-discoloring compositions, capsule pigments in which fragrances and the like are directly or microencapsulated are exemplified. it can.

The thermochromic composition includes (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reversible thermochromic composition comprising a reaction medium that determines the occurrence temperature of both of the color reactions. A sexual composition is suitable, which is encapsulated in microcapsules and applied as a reversible thermochromic microcapsule pigment.
The reversible thermochromic composition is described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-2398, and the like with a predetermined temperature (discoloration point) as a boundary. The color changes before and after, the color is decolorized in the temperature range above the high temperature side discoloration point, and the color is developed in the temperature range below the low temperature side discoloration point. Of the above two states, only one specific state exists in the normal temperature range. The other state is maintained as long as the heat or cold required for the state to develop is applied, but returns to the state exhibited in the normal temperature range when the heat or cold is not applied, and the hysteresis width is A heat-decoloring type microcapsule pigment in which a reversible thermochromic composition having a relatively small property (ΔH = 1 to 7 ° C.) is encapsulated in a microcapsule can be applied.
Further, relatively large hysteresis characteristics (ΔH = 8 to 50) described in JP-A-4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936 and the like. It shows a large hysteresis characteristic described in JP-A-2006-137886, JP-A-2006-188660, JP-A-2008-45062, JP-A-2008-280523, and the like. That is, the shape of the curve plotting the change in coloring density due to the temperature change is significantly different between the case where the temperature is raised from the lower temperature side than the discoloration temperature range and the case where the temperature is lowered from the higher temperature side than the discoloration temperature range. A reversible thermochromic composition that discolors by following a path and has color memory in a specific temperature range when the color is developed in a low temperature range below the complete color development temperature or in a high temperature range above the complete decolorization temperature. A heat-decoloring type microcapsule pigment can also be applied.
Specifically, as the reversible thermochromic composition having color memory, the complete color development temperature can be obtained only in a freezer, a cold region, or the like, that is, −50 to 0 ° C., preferably -40 to −. 5 ° C, more preferably -30 to -10 ° C, and the complete decolorization temperature is the frictional heat of the friction body, the temperature obtained from a familiar heating body such as a hair dryer, that is, 50 to 95 ° C, preferably 50 to 90 ° C. , More preferably, it is specified in the range of 60 to 80 ° C., and the ΔH value is specified in the range of 40 to 100 ° C., so that it can effectively function to maintain the color exhibited in the normal state (daily living temperature range).

The coloring material may be used alone or in admixture of two or more, and is used in the range of 0.1 to 30% by weight, preferably 1 to 20% by weight in the ink composition.

〔式中Ｒ_１は８〜１８のアルキル基、アルケニル基、或いはフェニル基、アルキルフェニル基を示し、Ｒ_２はＯＨ、ＯＭ、Ｒ_１−Ｏ−（ＣＨ_２ＣＨ_２Ｏ）_ｎを示し、Ｍはアルカリ金属、アルカノールアミンを示し、ｎは１〜３０の自然数を示す。〕 The phosphoric acid ester is a phosphoric acid monoester, a diester, a triester or the like composed of an aromatic or aliphatic functional group, an ethylene oxide group and a phosphoric acid group, and has an HLB value in the range of 14 to 20. When used alone, it brings about an improvement in lubrication performance, and when used in combination with the above-mentioned oil-absorbing amount of titanium oxide, it can be suppressed from adhering to the inner wall of the ink containing cylinder during movement due to ink consumption. The HLB value is a value before neutralization.
As the compound, for example, a compound given by the following general formula (1) can be applied.

[In the formula, R ₁ represents an alkyl group, an alkenyl group, or a phenyl group, an alkylphenyl group of 8 to 18, and R ₂ represents OH, OM, R ₁ −O− (CH ₂ CH ₂ O) _n , and M Indicates an alkali metal and an alkanolamine, and n indicates a natural number of 1 to 30. ]

Specifically, Phosphanol RD-715 (HLB: 14.0), RD-720 (HLB: 14.4), CP-120 (HLB: 15.0), RS-610NA (HLB:). 16.3), RS-710M (HLB: 17.0) [above, manufactured by Toho Kagaku Co., Ltd.], Plysurf A217E (HLB: 14.9), A219B (HLB: 16.2) [above, An example is (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

The phosphoric acid ester-based surfactant can be added in an amount of 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total amount of the ink composition.
If it is 0.01% by weight or less, it is difficult to obtain the desired effect, and even if it is added in excess of 10% by weight, the above effect is not improved, so no further addition is required.

Examples of the shear-thinning agent include xanthan gum, welan gum, succinoglycan (average molecular weight of about 1 to 8 million) in which the constituent monosaccharides are organic acid-modified heteropolysaccharides of glucose and galactose, guar gum, locust bean gum and the like. Polymers with a molecular weight of 100,000 to 150,000 containing the derivatives, hydroxyethyl cellulose, alginate alkyl esters, and alkyl esters of methacrylic acid as the main components, and increased gelling ability extracted from seaweeds such as glucomannan, agar, and caragenin. Viscous polysaccharides, benzylidene sorbitol and benziliden xylitol or derivatives thereof, crosslinkable acrylic acid polymers, inorganic fine particles, polyglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether polyoxypropylene Examples thereof include nonionic surfactants having an HLB value of 8 to 12 such as alkyl ethers, polyoxyethylene alkyl phenyl ethers, and fatty acid amides, and salts of dialkyl or dialkenyl sulfosuccinic acid, which can be used alone or in combination. ..
In particular, since succinoglycan has a higher viscosity in a stationary state (at low shear) than other glucans, it is excellent in storage stability of titanium oxide having a large specific gravity. Further, since the ink followability at the time of writing (during high shear) is improved by the combined use of the titanium oxide having an oil absorption amount and the phosphoric acid ester having an HLB value, long-term ink stability can be obtained by the configuration of the present invention. , A particularly useful material.

Further, a conventional general-purpose water-soluble organic solvent compatible with water can be used. Specifically, ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol mono. Examples thereof include ethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone and the like.
The water-soluble organic solvent may be used alone or in combination of two or more, and is used in the range of 2 to 60% by weight, preferably 5 to 35% by weight.

Further, a water-soluble resin can be added in order to impart stickiness and viscosity to the paper surface. Examples of the water-soluble resin include alkyd resin, acrylic resin, styrene maleic acid copolymer, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, dextrin and the like. The water-soluble resin may be used alone or in combination of two or more, and is used in the range of 1 to 30% by weight in the ink composition.

Further, resin particles can be blended. The resin particles have the effect of lowering the average specific gravity of the solid content in the ink composition and improving the dispersion stability of titanium oxide. In particular, those having an average particle size in the range of 0.2 to 5.0 μm are highly effective, and are blended in the range of 5.0 to 20.0% by weight in the total amount of the ink composition. If it is less than 5.0% by weight, the dispersion effect is insufficient, and if it exceeds 20.0% by weight, the viscosity of the ink becomes too high, which is not preferable.
Examples of the resin particles include SX863 (A), SX864 (B), SX865 (B), SX866 (A), SX866 (B), SX8782 (D), AE8865 [all manufactured by JSR Corporation], Nipol MH5055, and the like. Examples thereof include Nipol MH505A, Nipol MH8055 [all manufactured by Nippon Zeon Co., Ltd.], Low Pay OP-84J, Low Pay Ultra E, and Low Pay HP-1055 [all manufactured by Roam and Hearth].

In addition, if necessary, inorganic salts such as sodium carbonate, sodium phosphate, sodium acetate, pH adjusters such as organic basic compounds such as water-soluble amine compounds, benzotriazole, tolyltriazole, 2,5-dimercapto- Rust preventives such as 1,3,4-thiazidol, saponin, coal acid, sodium salt of 1,2-benzthiazolin 3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3 , Preservatives or antifungal agents such as 5,6-tetrachloro-4- (methylsulfonyl) pyridine, ureas, sorbits, mannittes, sucrose, glucose, reduced starch hydrolysates, wetting agents such as sodium acetate, A defoaming agent, a fluorine-based surfactant or a nonionic surfactant that improves the permeability of the ink may be used.
In addition, ascorbic acids, erythorbic acids, α-tocopherols, catechins, synthetic polyphenols, kodiic acid, alkylhydroxylamines, oxime derivatives, α-glucosylrutin, α-lipoic acid, phosphonates, phosphinates, sulfates, sulfoxyls Bubbles can also be chemically removed by adding acid salt, phosphite, thiosulfate, thiourea dioxide and the like.
In addition, N-vinyl-2-pyrrolidone oligomer, N-vinyl-2-piperidone oligomer, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, N-vinyl-ε-caprolactam By adding a thickening inhibitor such as an oligomer, the function in the infested form can be enhanced.
Further, a general-purpose lubricant can be used in combination, for example, metal soap, polyalkylene glycol fatty acid ester, ethylene oxide-added cationic surfactant, β-alanine type surfactant, N-acylamino acid, N-acylmethyl taurine. , 2,5-Dimercapto-1,3,4-Thiasiazol and its salts and oligomers, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate, α-lipoic acid , A condensate of N-acyl-L-glutamic acid and L-lysine, a salt thereof, or the like is used.

As the viscosity of the water-based ink having the above composition, it is preferable that the value measured by an E-type viscometer at 20 ° C. and 1 rpm is in the range of 500 to 3000 mPa · s, preferably 1000 to 2500 mPa · s.
When the viscosity exceeds 3000 mPa · s, it is effective from the viewpoint of suppressing the sedimentation of titanium oxide, but the writing feeling becomes heavy, and the ink followability at the time of writing and the dry-up property of the pen tip deteriorate, and the handwriting blurring. Is likely to occur. Further, if it is lower than 500 mPa · s, it is disadvantageous in terms of suppressing the sedimentation of titanium oxide, and the dryness of the handwriting is further lowered.
By satisfying the above-mentioned viscosity range, in addition to satisfying ink stability, writing performance, that is, writing feeling, initial writing, dryness of handwriting, and formation of good handwriting can be satisfied.
In addition, as the viscosity characteristic of the ink, the experimental formula (T = Kjn: where K is calculated, which is derived by the hydrodynamic measurement of the shear stress value (T) and the shear rate (j) value by the shear viscosity index [a viscometer]. The ink composition of the present invention is used in an ink in which the n value calculated by applying) is in the range of 0.4 to 0.9, preferably 0.5 to 0.8. It works more effectively.

The water-based ink composition is filled in a ballpoint pen having a ballpoint pen tip attached to a writing tip.
The structure and shape of the ballpoint pen itself are not particularly limited, and conventional general-purpose ones can be applied. For example, an ink container having an ink composition filled in a shaft tube is provided, and the ink container has a ball. An example is a ballpoint pen that communicates with a chip attached to the tip portion and has an ink backflow preventive body for preventing backflow in close contact with the end face of the ink.

The ballpoint pen tip will be described in more detail. A tip formed by holding a ball in a ball-holding portion in which the vicinity of the tip of a metal pipe is pressed and deformed inward from an outer surface, or a metal material is cut by a drill or the like. A tip formed by holding a ball in a ball holding portion formed by, or a ball held by a chip formed by cutting a metal pipe or a metal material and urged forward by a spring body, etc. Can be applied.
Further, cemented carbide, stainless steel, ruby, ceramic or the like can be applied to the ball, and those having a diameter in the range of 0.1 mm to 2.0 mm are preferably used.

As the ink storage cylinder, a metal processed body or a molded body made of a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate is preferably used in terms of low evaporation property and productivity of the ink. In particular, in a resin molded product, by using a transparent, colored transparent, or semi-transparent molded product, the ink can be visually recognized from the outside, giving a unique design effect, and the hue, remaining amount, etc. of the ink. Can be confirmed. Therefore, the effect of the ink composition of the present invention becomes more remarkable. In particular, the ink composition of the present invention is more useful because the ink composition made of polypropylene is remarkably adhered to the inner wall surface.
Further, when the inner diameter of the ink storage cylinder is small (specifically, 4 mm or less and particularly 3 mm or less), the ink moves faster during writing, so that the ink adheres to the inner wall surface significantly. Therefore, the ink composition of the present invention is more useful.
In addition to directly connecting the chip to the ink storage cylinder, the ink storage cylinder and the chip may be connected via a connecting member. The ink storage cylinder may be a ballpoint pen refill in which the refill is housed in a shaft cylinder made of resin or metal, or the shaft cylinder is used as an ink storage cylinder and directly in the shaft cylinder. Ink may be filled.

Further, an ink backflow preventive body (liquid plug) can be filled in the rear end portion of the ink composition filled in the ink containing cylinder.
As the ink backflow preventive body, either a liquid or a solid can be used, and examples of the liquid ink backflow preventive body include non-volatile media such as polybutene, α-olefinco oligomer, silicone oil, and refined mineral oil. If desired, silica, aluminum silicate, swellable mica, fatty acid amide and the like can be added to the medium. Further, as a solid ink backflow preventive body, a resin molded product can be mentioned. The liquid and solid ink backflow preventives can also be used in combination.

The ballpoint pen may be in either a cap type or a haunting type, and as a haunting type ballpoint pen, the writing tip portion provided on the ballpoint pen refill is exposed to the outside air inside the shaft tube (outer shaft). Any structure can be used as long as it is housed and the writing tip protrudes from the opening of the barrel by the operation of the retracting mechanism.
Examples of the operation method of the haunting mechanism include a knock type, a rotary type, and a slide type.
The knock type has a knock portion at the rear end of the barrel and the side surface of the barrel, and by pressing the knock portion, the writing tip of the ballpoint pen refill is made to appear and disappear from the opening at the front end of the barrel, or the barrel. By pressing the provided clip portion, a configuration can be exemplified in which the writing tip portion of the ballpoint pen refill is made to appear and disappear from the opening at the front end end of the barrel.
In the rotary type, a configuration in which a rotating portion is provided at the rear portion of the barrel and the writing tip portion of the ballpoint pen refill is retracted from the opening at the front end of the barrel can be exemplified by rotating the rotating portion.
The slide type has a slide portion on the side surface of the barrel, and by operating the slide, the writing tip of the ballpoint pen refill is made to appear and disappear from the front end opening of the barrel, or the clip portion provided on the barrel is slid. By doing so, it is possible to exemplify a configuration in which the writing tip of the ballpoint pen refill is made to appear and disappear from the opening at the front end of the barrel.
The infestation type ballpoint pen may be a composite type infestation type ballpoint pen (refill exchange type) in which a plurality of ballpoint pen refills are housed in a barrel.

Examples will be described below, but the present invention is not limited to these examples.
The table below shows the composition of the water-based inks for ballpoint pens of Examples and Comparative Examples. The numerical values of the compositions in the table indicate parts by weight. The ink viscosity is a value measured at 1 rpm with a rotational viscometer [RE80 manufactured by Toki Sangyo Co., Ltd.] at 20 ° C.

The contents of the raw materials in the table will be explained according to the note numbers.
(1) Made by Ishihara Sangyo Co., Ltd., Product name: Typake CR-50 (oil absorption 18)
(2) Made by Ishihara Sangyo Co., Ltd., Product name: Typake PF-739 (oil absorption 14)
(3) Made by Ishihara Sangyo Co., Ltd., Product name: Typake PF-736 (oil absorption 15)
(4) Made by TAYCA CORPORATION, Product name: Titanics JR-800 (oil absorption 29)
(5) Made by Ishihara Sangyo Co., Ltd., Product name: Typake R-780 (oil absorption 33)
(6) Manufactured by Sanyo Pigment Co., Ltd., trade name: S.A. S. Blue GLL
(7) Manufactured by Dainichiseika Co., Ltd., Product name: TC Red FG
(8) Made by Big Chemie Japan Co., Ltd., Product name: DISPER BYK-191
(9) Made by Big Chemie Japan Co., Ltd., Product name: DISPER BYK-2015
(10) Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf A217E (HLB: 14.9)
(11) Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf A219B (HLB: 16.2)
(12) Made by Toho Chemical Industry Co., Ltd., Product name: Phosphanol RD-715 (HLB: 14.0)
(13) Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf AL (HLB: 5.6)
(14) Made by Arch Chemicals Japan, trade name: Proxel XL-2
(15) Made by Roam and Hearth Co., Ltd., Product name: Lowpaque Ultra E (solid content 30%)
(16) Succinoglycan (17) Xanthan gum

Ink Preparation In Examples and Comparative Examples, components other than the shear thinning agent were added to water, mixed and stirred, then the shear thinning agent was added, and the mixture was stirred at 20 ° C. at 4000 rpm for 1 hour. Then, each ink was prepared by filtering.

Preparation of Ink Backflow Prevention Body After adding 1.5 parts of fatty acid amide as a thickener to 98.5 parts of polybutene as a base oil, the mixture was kneaded with three rolls to obtain an ink backflow prevention body.

0.15 g of the ink compositions of the above Examples and Comparative Examples are fitted to one end of a transparent polypropylene pipe (inner diameter 1.7 mm) by a stainless steel chip holding a cemented carbide ball having a diameter of 0.5 mm. A ballpoint pen refill was produced by filling the refill with the ink and arranging the ink backflow preventive body at the trailing end. Further, a sample ballpoint pen was produced by incorporating the ballpoint pen refill into a transparent shaft tube (rear end knock type).

The following test was performed using the sample ballpoint pen and the refill.
Written test (visibleness confirmation test)
A spiral writing tester adjusted to a writing load of 100 g and a writing angle of 70 degrees after each sample ballpoint pen confirmed to be writable was left to stand in an environment of 50 ° C for 30 days immediately after preparation and in a horizontal position. A writing test was carried out on JIS P3201 writing paper A at a writing speed of 4 m / min until the ink was exhausted, and the state inside the ink containing cylinder was visually confirmed from the outside.
Ink stability test The ballpoint pen refill was allowed to stand with the tip facing downward and left in an environment of 50 ° C. for 60 days. Then, the state of the ink in the refill was visually confirmed at room temperature. Furthermore, for those that were not separated into layers, a spiral circle was handwritten on the paper.
The results of each of the above tests are shown in the table below.

The evaluation of the test results is as follows.
Written test ◯: As the ink is consumed, the ink moves without adhering to the wall surface, and visibility can be ensured until the end.
Δ: Adhesion to the wall surface is partially observed as the ink is consumed.
X: Ink always remains attached to the wall surface until the writing is completed.
Ink stability test ◯: Titanium oxide did not settle, showing the same state as in the initial stage, and good writing was possible.
Δ: Although some ink separation is observed compared to the initial stage, it is at a practical level at the time of writing.
X: Ink is layer-separated.

Claims (8)

A water-based ink composition containing at least titanium oxide, a phosphoric acid ester, a shear- degrading agent, and water, wherein the titanium oxide has an oil absorption amount of 12 to 25 ml / 100 g and an HLB value of the phosphoric acid ester. A water-based ink composition for a ball pen in the range of 14 to 20. The water-based ink composition for a ballpoint pen according to claim 1, wherein the viscosity at 1 rpm by a rotational viscometer is in the range of 1000 to 2500 mPa · s (20 ° C.). The water-based ink composition for a ballpoint pen according to claim 1 or 2, wherein the phosphoric acid ester is added in the range of 0.01 to 10% by weight based on the total amount of the ink composition. The water-based ink composition for a ballpoint pen according to any one of claims 1 to 3, wherein the shear thinning agent is succinoglycan. The water-based ink composition for a ballpoint pen according to any one of claims 1 to 4, wherein the titanium oxide is added in the range of 0.1 to 20% by weight based on the total amount of the ink composition. A ballpoint pen in which the water-based ink composition for a ballpoint pen according to any one of claims 1 to 5 is incorporated in a transparent ink storage cylinder. The ballpoint pen according to claim 6, wherein the inner diameter of the ink containing cylinder is 4 mm or less. The ballpoint pen according to claim 6 or 7, wherein the material of the ink containing cylinder is polypropylene resin.