JP2021024928A - Aqueous ink composition - Google Patents

Abstract

To provide an aqueous ink composition capable of: forming a handwriting which has preferably dryness and has a sense of beauty of opaque property with preferable color development of a colorant and concealment property; suppressing blur or the like and achieving preferable writing property; achieving cap-off property which is contrary to the dryness; and achieving preferable sedimentation stability of a component in the ink and excellent in storage stability.SOLUTION: An aqueous ink composition includes titanic oxide, aluminum oxide and talc.SELECTED DRAWING: None

Description

The present invention relates to a water-based ink composition, particularly a water-based ink composition that can be suitably used as a water-based ink composition for a water-based ballpoint pen.

In recent years, water-based ballpoint pens that draw opaque handwriting that creates aesthetics with "clear", "brilliant", and "beautiful" colors on colored paper, black paper, photographs, cloth, leather, etc., as well as white paper, have been introduced. Are known. As such a water-based ball pen, a water-based ink composition containing a white pigment such as titanium oxide and having a concealing property is often used.

Patent Document 1 uses black paper by using an aqueous ink composition containing a specific amount of titanium oxide, specific hollow resin particles, an aqueous soluble organic solvent, a shear thinning agent, and a phosphoric acid ester-based activator. A water-based ballpoint pen that has visibility and does not cause blurring or line skipping is described.
Patent Document 2 discloses a ballpoint pen capable of recording clear handwriting on dark colored paper using an ink containing a specific amount of titanium oxide and specific resin particles and having a solid content adjusted to a specific range with respect to the total amount of ink. Has been done.
Patent Document 3 describes a water-based ink composition for a water-based ballpoint pen containing titanium oxide, a coloring pigment, and alumina, which does not cause ink adhesion to the inner wall of the ink storage tube and allows the remaining amount of ink to be clearly visible. There is.
Patent Document 4 contains a white pigment, a plate-shaped talc, and a water-soluble resin, has good ink ejection, prevents the white pigment from penetrating into paper, and has a high concentration of strokes, and is a water-based white for ballpoint pens. Pigment inks are listed.

When drawing a handwriting on black paper or the like, it is conceivable to increase the content of titanium oxide or aluminum oxide in the ink composition in order to improve the concealing property.
However, the specific gravities of titanium oxide and aluminum oxide are large, and if the content is increased, they will settle in the ink. Further, due to the influence of titanium oxide and aluminum oxide, it may be difficult to adjust the color to a desired color.
On the other hand, if the contents of titanium oxide and aluminum oxide in the ink are lowered, the drying property and the hiding property are deteriorated. If the drying property is improved by increasing the drying rate of the ink for a water-based ballpoint pen, it becomes impossible to secure good writing performance when the ink is left uncapped (cap-off property).

JP-A-2009-185166 Japanese Unexamined Patent Publication No. 2001-180177 JP-A-2016-124894 Japanese Patent No. 3122781

INDUSTRIAL APPLICABILITY The present invention has good drying property, good color development and hiding property of a colorant, can form a handwriting having an opaque aesthetic appearance, has good writing property without blurring, and is contrary to drying property. It is an object of the present invention to obtain an aqueous ink composition having good cap-off property, which is a characteristic of the ink, which has good sedimentation stability of components in the ink and excellent storage stability.

As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved by an aqueous ink composition containing titanium oxide, aluminum oxide, and talc, and complete the present invention. I arrived. Specifically, it is as follows.
[1] A water-based ink composition containing titanium oxide, aluminum oxide, and talc.
[2] The water-based ink composition according to [1], which is used for writing instruments.
[3] The water-based ink composition according to [1] or [2], wherein the total content of titanium oxide, aluminum oxide and talc is 10 to 40% by mass with respect to the total amount of the water-based ink composition.
[4] The water-based ink according to any one of [1] to [3], wherein the ratio (mass ratio) of the content of titanium oxide to the total content of aluminum oxide and talc satisfies the following formula (1). Composition.
Equation (1):
1/99 ≤ Titanium oxide content / (Aluminum oxide content + Talc content) ≤ 5/1
[5] The water-based ink composition according to any one of [1] to [4], wherein the content of talc is 2 to 15% by mass with respect to the total amount of the water-based ink composition.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to form a handwriting having good drying property, good color development and hiding property of a colorant, and an opaque aesthetic appearance, and good writing property without blurring, which is contrary to drying property. Provided is an aqueous ink composition having good cap-off property, which is a characteristic of the ink, good settling stability of components in the ink, and excellent storage stability.

The water-based ink composition of the present invention contains titanium oxide, aluminum oxide, talc, and an aqueous solvent, and if necessary, a colorant, a viscosity modifier (thickener), a wetting agent, and a lubricant. It may contain one or more selected from the group consisting of agents and dispersants. Further, other components other than these (one or more selected from the group consisting of pH adjusters, preservatives, fungicides, resins and the like) may be contained. Each component contained in the water-based ink composition of the present invention will be described below.

[Titanium oxide]
Titanium oxide exhibits a function as a white colorant and a function as a concealing material. The crystal structure is not particularly limited, and titanium oxide having various crystal structures such as rutile type and anatase type is used.
The average particle size of the titanium oxide ₍₅₀ value D by a laser diffraction type particle size distribution meter) is not particularly limited, masking property, preventing such clogging or settling occurs in the pen tip, in consideration of cost, etc. 0.1 The one of 5 μm is used. It is preferably 0.1 to 1 μm, and more preferably 0.3 to 0.5 μm.
As the titanium oxide, either untreated titanium oxide or surface-treated titanium oxide is used. A treatment agent surface-treated is preferably used. The treatment agent includes, for example, aluminum hydroxide (aluminum hydroxide), aluminum oxide, zirconium oxide, silicon oxide, zinc oxide, phosphoric acid (salt), fatty acid (salt), polyol compound, amine compound, silicone compound and the like. One or more compounds selected from the group can be mentioned.

As the titanium oxide, commercially available fine particles can be used. Further, in order to increase the dispersion efficiency, a commercially available aqueous dispersion can also be used.
Examples of titanium oxide include KRONOS KA-10, KA-15, KA-20, KA-30, KA-35, KA-80, KR-310, KR-380, KR-380-N, KR-460, KR-480, KR-270 (above, trade name manufactured by Titanium Industry Co., Ltd.), TITONE SR-1, R-3L, R-5N, R-7E, R-21, R-24, R-25, R-32 , R-38l, R-42, R-45M, R-61N, R-62N, R-310, R-650, D-918, R-970, FTR-700, TCR-52, GTR-100, A -110, A-150, A-190, A-197 (above, product name manufactured by Sakai Chemical Industry Co., Ltd.), TIPAQUE R-550, R-580, R-630, R-670, R-680, R-780 , R-780-2, R-820, R-830, R-930, R-980, PR-690, PF-691, PF-711, PF-736, PF-737, PF-742, PF-739 , PF-740, PC-3, S-305, CR-50, CR-50-2, CR-57, CR-58, CR-58-2, CR-Super70, CR-80, CR-85, CR -90, CR-90-2, CR-93, CR-97, A-100, A-220 (above, product name manufactured by Ishihara Sangyo Co., Ltd.), TITANIX JR-300, JR-301, JR-403, JR- 405, JR-600A, JR-600E, JR-603, JR-605, JR-701, JR-800, JR-801, JR-805, JR-806, JR-906, JR, JRNC, JA-1, JA-C, JA-3, JA-4, JA-5 (above, product name made by Teika), TA-100, TA-200, TA-300, TA-400, TR-600, TR-700, TR -840, TR-900 (above, product name manufactured by Fuji Titanium Industry Co., Ltd.), Ti-Pure R-700, R-706, R-900, R-901, R-902, R-931 (above, DuPont Japan) -One or more types selected from the group consisting of (trade name manufactured by Limited) and the like can be used.

[Aluminum oxide]
Aluminum oxide exhibits a function as a white colorant and a function as a concealing material. The crystal type is not particularly limited, and may contain crystal water or the like. Usually, α, β, γ type and the like are used. The shape of the aluminum oxide particles is not particularly limited, but may be scaly (flake-shaped) fine particles, hexagonal plate-shaped, disc-shaped, or a mixture thereof, which is caused by pulverization or the like. It does not have to have a uniform shape.
The average particle size of the aluminum oxide ₍₅₀ value D by a laser diffraction type particle size distribution meter) is not particularly limited, masking property, preventing such clogging or settling occurs in the pen tip, in consideration of cost, etc. 0.1 The one of 5 μm is used. It is preferably 0.1 to 3 μm. When scaly aluminum oxide is used, its aspect ratio (average particle size / average thickness) may be more than 1, preferably 5 or more, and more preferably 10 or more. The upper limit of the aspect ratio is not particularly limited, but is usually 80 or less, preferably 60 or less.
As the aluminum oxide, either untreated aluminum oxide or surface-treated aluminum oxide is used. An untreated one is preferably used.

As the aluminum oxide, a commercially available product can be used. Further, in order to increase the dispersion efficiency, a commercially available aqueous aluminum oxide dispersion can also be used.
Examples of aluminum oxide include Seraph YFA02025, YFA10030, YFA05025 (above, product name manufactured by Kinsei Matec), Terraces BMM, BMF, BMN, BMP, BMI, BMM-B, BMF-B, BMN-B, BMP-B. , BMI-B (all manufactured by Kawai Lime Industry Co., Ltd.), etc., and one or more selected from the group can be used.

[talc]
Talc exerts a function as a white colorant and a function as a concealing material. Talc is hydrous magnesium silicate and can be obtained by crushing talc or the like.
The average particle diameter of the talc ₍₅₀ value D by a laser diffraction type particle size distribution meter), but are not limited to, masking property, preventing such clogging or settling occurs in the pen tip, in consideration of cost and the like 0.1~5μm Is used. It is preferably 0.5 to 4 μm, and more preferably 1 to 3 μm.
Talc is usually a particle having a plate-like shape, and its aspect ratio (average particle diameter / average thickness) may be 1 or more, preferably 5 or more, and more preferably 10 or more. The upper limit of the aspect ratio is not particularly limited, but is usually 10,000 or less, preferably 8,000 or less.
As talc, either untreated talc or surface-treated with a treating agent is used. An untreated one is preferably used.

As the talc, a commercially available product can be used. For example, MAICRO ACE SG-95, SG-2000, P-2, P-3, P-4, P-6, P-8, NANO ACE D-1000, D-800, D-600 (above, Japan Talc) (Product name), P talc, PH talc, PS talc, TTK talc, TT talc, T talc, ST talc, Hirac, Microlite, Himicron HE5 (above, Takehara Chemical Industry Co., Ltd. product name), LMS- 100, LMS-200, LMS-300, LMS-3500, LMS-400, LMP-100, PKP-53, PKP-80, PKP-81 (above, product name manufactured by Fuji Talc Industry Co., Ltd.), JM-209, JM One or more selected from the group consisting of -309 (above, trade name manufactured by Asada Flour Milling Co., Ltd.) and the like can be used.

[Contents of titanium oxide, aluminum oxide and talc]
The contents of titanium oxide, aluminum oxide and talc can be appropriately set according to the type, shape, size and the like of each, and according to the desired characteristics.
The content of titanium oxide is not particularly limited, but can be, for example, in the range of 0.1 to 30% by mass, preferably 1 to 20% by mass, based on the total amount of the aqueous ink composition. If the content is less than 0.1% by mass, there may be a problem in terms of background hiding property and color development property when writing on dark colored paper such as black paper. If the content exceeds 30% by mass, there is a risk of problems in terms of sedimentation of titanium oxide over time and blurring of handwriting.
The content of aluminum oxide is not particularly limited, but can be, for example, in the range of 0.1 to 30% by mass, preferably 1 to 20% by mass, based on the total amount of the aqueous ink composition. If the content is less than 0.1% by mass, there is a possibility that problems may occur in terms of background hiding property, color development property, ink fluidity, ink handling property, etc. when writing on dark colored paper. If the content exceeds 30% by mass, problems may occur in terms of precipitation of aluminum oxide with time, blurring of handwriting, difference in whiteness before and after drying, ink fluidity, ink handling, and the like. The present inventors have found that the above effect can be obtained by including aluminum oxide particles in the water-based ink composition, and the above effect cannot be obtained by aluminum oxide coating the surface of titanium oxide or the like. It was.
The content of talc is not particularly limited, but can be, for example, in the range of 1 to 30% by mass, preferably 1 to 20% by mass, and more preferably 3 to 15% by mass with respect to the total amount of the aqueous ink composition. If the content is less than 1% by mass, problems may occur in terms of drying speed, background hiding property when writing on dark colored paper, color development, handwriting visibility, ink fluidity, ink handling property, cap-off property, etc. There is. If the content exceeds 30% by mass, problems may occur in terms of talc sedimentation over time, handwriting blurring, ink fluidity, ink handling, and the like.
The total content of titanium oxide, aluminum oxide, and talc is not particularly limited, but is, for example, 5 to 50% by mass, preferably 10 to 40% by mass, more preferably, based on the total amount of the aqueous ink composition. Can be in the range of 15 to 35% by mass. If it is out of the range of 5 to 50% by mass, problems may occur in terms of drying speed, color development, sedimentation stability, handwriting blurring, ink fluidity / outflow property, and the like.

The content ratio (mass ratio) of titanium oxide and aluminum oxide is not particularly limited, but as titanium oxide / aluminum oxide, for example, 5/95 to 95/5, preferably 10/90 to 90/10, more preferably 30 It can be in the range of / 70 to 90/10.
The ratio (mass ratio) of the titanium oxide content to the total amount of the aluminum oxide content and the talc content is not particularly limited, but the titanium oxide content / (aluminum oxide content + talc content) is defined as For example, it can be in the range of 1/99 to 5/1, preferably 1/9 to 2/1, and more preferably 1/5 to 1/1.
The present inventors presume that the balance between the drying property, the precipitation stability and the color developing property of the water-based ink composition is good due to the whiteness, particle shape and specific gravity of talc.

[Aqueous solvent]
As the aqueous solvent used in the aqueous ink composition of the present invention, water or a mixed solvent of water and a water-soluble organic solvent is used. When a resin emulsion or an aqueous dispersion is blended in the water-based ink composition, the water-based solvent derived from these is also blended in the water-based ink composition as a water-based solvent as a result.
Water is not particularly limited as long as it is used as an aqueous solvent for the aqueous ink composition. For example, water that does not contain a large amount of impurities such as ion-exchanged water, distilled water, pure water, and tap water is used.
The water-soluble organic solvent is not particularly limited as long as it is used as the water-soluble organic solvent of the water-based ink composition. For example, lower alcohols such as ethanol, isopropanol and butanol, polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, glycerin and trimethylolpropane, and monoalkyl ethers of these polyhydric alcohols. At least one selected from the group consisting of monoalkyl ether acetates of these polyhydric alcohols is used. Preferably, ethylene glycol, propylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol mono n-propyl ether. One or more selected from the group consisting of is used.

The content of the aqueous solvent may be appropriately set, for example, in the range of 10 to 90% by mass, preferably 20 to 80% by mass, and more preferably 30 to 70% by mass with respect to the total amount of the aqueous ink composition. it can. If the content is less than 10% by mass, sedimentation of components and blurring of handwriting are likely to occur with time, and fluidity may be poor, and handleability and ink outflow may be deteriorated. If the content exceeds 90% by mass, the viscosity of the water-based ink composition becomes too low, making it difficult to control the water-based ink composition that flows out when used as a writing instrument, and the handwriting becomes too thin, resulting in good background hiding property. There is a risk that the color development will not be obtained and the aesthetics will deteriorate.

[Colorant]
The colorant is used to give the handwriting of the water-based ink composition of the present invention a aesthetic effect and a desired color tone. The colorant has properties such as good writing property without blurring, good drying property and cap-off property, good sedimentation stability of components in ink, and excellent storage stability. Can be incorporated into an aqueous ink composition.
The colorant is not limited as long as it is used in a water-based ink composition, particularly a water-based ink composition for a water-based ballpoint pen. One or more selected from the group consisting of inorganic pigments, organic pigments, dyes, colored resin balls, etc. that exhibit an arbitrary color tone can be used.
As the inorganic pigment, for example, one selected from the group consisting of metal powders such as carbon black, red iron oxide, yellow iron oxide, ultramarine, dark blue, aluminum powder and bronze powder, fluorescent pigments, pearl pigments, and bright pigments. The above can be used.
Known organic pigments and dyes include, for example, known coloring pigments such as phthalocyanine, azo, quinacdrine, anthraquinone, dioxane, indigo, thioindigo, perinone, perylene, indolenone, and azomethine. One or more selected from the group consisting of colored dyes and fluorescent dyes such as fluorescent pigments, anthraquinone-based, methine-based, carbonium-based, and metal complex salt-based dyes can be used.
As the colored resin sphere, a spherical, irregular, hollow, flat or the like resin sphere is colored with one or more of an inorganic pigment, an organic pigment or a dye exhibiting an arbitrary color tone. Examples of the resin material for forming the colored resin sphere include polyethylene, polypropylene, vinyl chloride, polymethacrylate, benzoguanamine, melamine resin, nylon and the like.

The content of the colorant may be appropriately set so that the water-based ink composition has a desired color tone, for example, 0 to 40% by mass, preferably 0 to 30% by mass, more preferably with respect to the total amount of the water-based ink composition. Can be in the range of 0 to 15% by mass. If the content exceeds 40% by mass, the viscosity becomes too high, and in terms of ink flowability from the tip of the writing instrument (ink does not flow out), ink handleability, settling stability, handwriting blurring, manufacturing cost, etc. It can be a problem.

[Viscosity adjuster (thickener)]
A viscosity modifier (thickener) may be included for adjusting the viscosity. The viscosity modifier (thickener) is not limited as long as it is used in a water-based ink composition, particularly a water-based ink composition for a water-based ballpoint pen. For example, polysaccharides and derivatives such as xanthan gum, welan gum, succinoglycan (leozane), daiyutan gum, guar gum, locust bean gum and derivatives thereof, cellulosic polymers, crosslinkable acrylic acid polymers, alkaline thickening acrylics. One or more selected from the group consisting of based resins, urethane-associated thickeners, N-vinylacetamide-based resins, inorganic fine particles, and the like can be used.
The content of the viscosity modifier (thickener) is appropriately set so that the aqueous ink composition has an appropriate viscosity according to the application. For example, it can be in the range of 0 to 20% by mass, preferably 0.1 to 10% by mass, based on the total amount of the water-based ink composition.

[Wetting agent]
A wetting agent may be included for adjusting the dryness and the like. The wetting agent is not limited as long as it is used in a water-based ink composition, particularly a water-based ink composition for a water-based ballpoint pen. For example, from glycols such as glycerin, diglycerin, triglycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, sugars, ureas, derivatives thereof and the like. One or more selected from the group can be used.
The content of the wetting agent in the water-based ink composition is appropriately set so that characteristics such as dryness of the ink are desired. For example, it can be in the range of 0.1 to 30% by mass, preferably 1 to 20% by mass, based on the total amount of the water-based ink composition.

[lubricant]
A lubricant may be included to improve the slip of the water-based ballpoint pen. The lubricant is not limited as long as it is used for a water-based ink composition, particularly a water-based ink composition for a water-based ballpoint pen, and a commercially available lubricant can be used. For example, Phosphanol series such as Phosphanol PE-510, ML-220, ML-200, RL-310 (above, trade name manufactured by Toho Chemical Industry Co., Ltd.), Nikkor series such as Nikkor DDP-2 (Nikko Chemicals Co., Ltd.) (Product name), Prysurf series (trade name manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) such as POE alkyl ether phosphate, and one or more selected from the group consisting of fatty acids such as sodium oleate can be used.
The content of the lubricant in the water-based ink composition is not particularly limited, but can be, for example, in the range of 0.1 to 10% by mass, preferably 0.1 to 5% by mass, based on the total amount of the water-based ink composition. ..

[Dispersant]
A dispersant may be contained for the purpose of stabilizing the dispersion of the contained titanium oxide, aluminum oxide, talc and the pigment contained as a colorant. The dispersant has an effect of preventing the pigment from settling by stabilizing the pigment after dispersion, and at the same time, also functions as a vehicle / binder for forming a coating film of the aqueous ink composition. The dispersant is not limited as long as it is used in a water-based ink composition, particularly a water-based ink composition for a water-based ballpoint pen, and a commercially available one can be used. For example, styrene- (meth) acrylic resin (emulsion), styrene-maleic acid resin (emulsion), styrene-maleic acid ester resin (emulsion), (meth) acrylic resin (emulsion), (meth) acrylic acid. One or more selected from the group consisting of ester resins (emulsions), cellulosic compounds such as sodium carboxymethyl cellulose and the like can be used.
The content of the dispersant in the water-based ink composition is not particularly limited, but can be, for example, in the range of 0.1 to 30% by mass, preferably 1 to 10% by mass, based on the total amount of the water-based ink composition. If the content exceeds 30% by mass, the dispersant acts as a coagulant and may cause pigment agglomeration. If the content is less than 0.1% by mass, the pigment may not be sufficiently dispersed and pigment aggregation may occur. When pigment aggregation is caused, pigment settling occurs in the ink, which may deteriorate the ink outflow property from the writing instrument.

[Other additives]
Other additives may be added to the water-based ink composition of the present invention, if necessary. The other additives are not limited as long as they are used in a water-based ink composition, particularly a water-based ink composition for a water-based ballpoint pen.
For example, pH adjusters (hydroxides (aqueous solutions) of alkali metals such as sodium hydroxide, potassium hydroxide and lithium hydroxide), amine compounds such as triethanolamine, diethanolamine, monoethanolamine, dimethylethanolamine, morpholine and triethylamine. , Ammonia (water), etc.), Antiseptic fungicides (benzoisothiazolin-based fungicides, pentachlorophenol-based fungicides, cresol-based fungicides, propylene glycol-based fungicides, iodine-based fungicides Antiseptic agents such as agents), rust preventives (benzotriazole, tolyltriazole, dicyclohexylammonium hydroxide, etc.), surfactants, defoaming agents, leveling agents, anti-aggregation agents, ultraviolet absorbers, infrared absorbers, Antioxidants, non-thermally discoloring pigments, non-thermally discoloring dyes, fluorescent whitening agents and the like can be used in appropriate amounts.

[Viscosity of water-based ink composition]
The viscosity of the water-based ink composition may be appropriately set, for example, 1 to 100,000 mPa · s, preferably 100 to 20,000 mPa · s, more preferably 1,000 to 10,000 mPa · s (E-type rotational viscosity). It can be in the range of a meter (for example, TVE type viscometer manufactured by Toki Sangyo Co., Ltd., 3 ° R14 cone, 0.5 rpm). When the viscosity of the water-based ink composition is less than 100 mPa · s, the ink flows out from the tip of the writing instrument (the water-based ink composition flows out excessively during writing and it is not possible to form a handwriting accurately), and the sedimentation stability and the like. It can be a problem. If the viscosity of the water-based ink composition exceeds 50,000 mPa · s, the viscosity becomes too high, and the ink flowability from the tip of the writing instrument (ink does not flow out), ink handleability, sedimentation stability, handwriting blurring, etc. There is a risk of problems in terms of manufacturing costs and the like.

[Use]
The water-based ink composition of the present invention can be used for both writing instruments and printing. As a writing instrument, the pen tip is a ball or a fiber bundle, and the ink accommodating part is a free accommodating tube or a core type writing instrument, for example, a marker, felt-tip pen, ballpoint pen, etc., regardless of valve type or non-valve type. Can also be used. In particular, it is most suitable for water-based ballpoint pens.

When a water-based ballpoint pen is constructed using the water-based ink composition of the present invention, a known ballpoint pen member may be used. For example, as the ink storage tube, a known material and size can be applied as it is. As the material of the ink storage tube, for example, a pipe made of synthetic resin such as polyethylene or polypropylene, or a metal pipe can be adopted. Further, as the ballpoint pen tip, the same material and structure as those used in known water-based ballpoint pens can be adopted.

[Method for preparing water-based ink composition]
The method for producing the water-based ink of the present invention is not particularly limited, and any known method for preparing a water-based ink composition can be used.
For example, all the components are put into a container and mixed and stirred by a device such as a ball mill, a bead mill, a roll mill, a Henschel mixer, a homomixer, a propeller stirrer, a homogenizer, a high-pressure homogenizer, a kneader, and a dissolver to disperse the ink. Can be prepared.
For example, an aqueous solvent, a dispersant, titanium oxide, aluminum oxide, talc, and a colorant are put into a container, and the dispersion is produced by mixing and stirring with the above-mentioned apparatus to disperse, and then the remaining components are added. Inks can be prepared by mixing and stirring.
For example, after producing a dispersion containing titanium oxide, a dispersion containing aluminum oxide, a dispersion containing talc, and a dispersion containing a colorant, these dispersions are mixed, and the remaining components are added. Inks can be prepared by mixing and stirring.
When preparing the water-based ink composition, coarse particles, gas, and bubbles may be removed by performing operations such as filtration, centrifugation, and defoaming. Means such as heating, cooling, pressurizing, depressurizing, and replacing the inert gas can also be adopted when preparing the water-based ink composition. Further, an aging step may be performed after the ink is prepared.

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples. Unless otherwise specified, "%" means "mass%" and "part" means parts by mass.

[Component components of water-based ink composition]
The following components were prepared as constituents of the water-based ink composition.
(Titanium oxide)
"KRONOS KR-380N (manufactured by Titan Kogyo, aluminum oxide, silicon oxide, zinc oxide treatment, average particle size 0.3 μm)
(Aluminum oxide)
"Seraph YFA02050" (manufactured by Kinsei Matek, plate-shaped, average particle size 2.0 μm, aspect ratio 45-55)
(talc)
"Talc SG-95" (manufactured by Japan Talc, average particle size 2.5 μm)

(Light calcium carbonate)
"Characteristic light calcium carbonate" (manufactured by Maruo Calcium)
(silica)
"ACEMATT (registered trademark) HK400" (manufactured by EVONIK, average particle size 6.3 μm)
(Colorant)
The following colorants were mixed to prepare a dark brown colorant.
"A3 Yellow" (manufactured by Dainichiseika Kogyo Co., Ltd.)
"HOSTAPERM (registered trademark) ORANGE GR" (manufactured by Clariant)
"CINQUASIA (registered trademark) PINK D 4450" (manufactured by BASF)
"Printex® G" (manufactured by Orion Engineered Carbons)
(Viscosity modifier)
"Primal (registered trademark) ASE-60" (manufactured by Rohm and Haas Japan)
(Wetting agent)
"Purified glycerin" (manufactured by New Japan Chemical Co., Ltd.)
(Dispersant)
"Joncryl® 683" (BASF, styrene-acrylic resin emulsion)
"Hiros-X1" (manufactured by Seiko PMC)

[Examples 1 to 7, Comparative Examples 1 to 6]
Using the above components, an aqueous ink composition having the composition shown in Table 1 was prepared by the following method.
Further, a water-based ballpoint pen was produced by the following method using the obtained water-based ink composition.
(Method for preparing water-based ink composition)
Ion-exchanged water and a colorant were added to the titanium oxide dispersant obtained by mixing water, titanium oxide and a dispersant, and the mixture was stirred with a dissolver stirrer for 5 minutes.
Then, a lubricant, aluminum oxide, and talc were added, and the mixture was stirred for 15 minutes.
After adding a pH adjuster and a dispersant and stirring for 30 minutes, an associative thickener was added and the mixture was stirred for 60 minutes.
Finally, the remaining components such as a wetting agent are added, ion-exchanged water is further added so that the amount of the water-based ink composition corresponds to 100 parts by mass, and the mixture is stirred for 10 minutes to prepare a water-based ink composition. did.
(How to make a water-based ballpoint pen)
The obtained water-based ink composition was filled in a polypropylene ink storage tube having a stainless steel ballpoint pen tip (ball: cemented carbide, diameter 1 mm) attached to one end, and an ink backflow preventer (gelled polybutene). Was filled to prepare a ballpoint pen refill. Next, a ballpoint pen refill was attached to the main body, a cap was attached, air in the tube was removed by a centrifuge, and then a breech plug was attached to obtain an aqueous ballpoint pen using each aqueous ink composition.
Using these water-based ballpoint pens, the water-based ink composition was evaluated as follows.
The following evaluation was performed using the obtained water-based ink composition or water-based ballpoint pen. The results are also shown in Table 1.

<Drying speed>
Using each water-based ballpoint pen, a V-shape with a side of 15 mm was written on a blank sheet of paper in an atmosphere of a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5% (constant temperature bath) for 36 characters (180 seconds) every 5 seconds. Five seconds after writing the last V-shape, the art side of the art paper was applied to the handwriting, and a load tool (weight) of 50φ500 g was placed on the written part and rubbed five times. After that, the art paper was released, and the time when the V-shaped transfer disappeared was defined as the drying time, and the drying rate was evaluated.

<Cap-off property>
Place each water-based ballpoint pen horizontally with the cap removed, leave it in an atmosphere of temperature 20 ± 2 ° C and humidity 65 ± 5% (constant temperature bath) for 6 hours, and then write 10 15φ circles by hand. (Evaluation method for examining the number of circles written before the blur disappeared in the handwriting and returned to normal handwriting while writing the circles 10 times) was performed and evaluated according to the following evaluation criteria.
◎: All 10 circles can be written normally ○: Normal writing is possible after 2 circles △: Normal writing is possible after 5 circles ×: All 10 circles are cassoulet

<Settlement stability>
Each water-based ballpoint pen was attached to a centrifuge so that the pen tip faced the outside of the rotation circumference, and after performing a sedimentation promotion test by rotating it, the time during which writing was not possible was determined as the number of promotion days and the sedimentation stability was evaluated. ..
The calculation of the number of promotion days is the following total,
"If the emulsion suspension-like product is allowed to stand for one year, the gravity of the earth (1 xg) is added to the product for one year. The gravity for this one year is integrated into the following equation.
1 (year) x 365 (day) x 24 (hours) x 1 (xg) = 8,760 (xg) x 1 (hours)
That is, the effect of gravity corresponding to one year can be obtained by centrifuging with a centrifugal force of 8,760 xg for 1 hour (or for 10 minutes with a centrifugal force of 52,560 xg). "
It was calculated with reference to.
When "H-38F" (manufactured by Koksan Co., Ltd .; centrifugal radius 20 mm) is used as the centrifuge, the centrifugal treatment at 2,000 rpm for 1 minute corresponds to an inverted standing for about 0.62 days.
A written test is performed after centrifugation at 2,000 rpm for an arbitrary time using a centrifuge "H-38F", and then a centrifugal treatment at an arbitrary time at 2,000 rpm, a written test, a centrifugal treatment at an arbitrary time at 2,000 rpm, and a written test. , And the centrifugation and the test were repeated.
The writing test is a ten-maru writing evaluation in which 10 15φ circles are written by hand (an evaluation method that examines the number of circles written before the handwriting disappears and the handwriting returns to normal while writing the circle 10 times. ) Was performed, and the number of conversion days after 6 circles was derived for normal writing.

<Beauty of handwriting>
For each water-based ballpoint pen, a 20m writing test was conducted using a writing tester to continuously draw a circle on high-quality paper under the conditions of writing angle: 65 °, load: 100 gf, writing speed: 7 cm / sec, rotation: yes. , The number of inks (ink on the ball of the pen tip that was not transferred to the paper and accumulated on the pen tip adhered to the paper) was visually counted and evaluated according to the following criteria.
Evaluation 5: 5 or less bots Evaluation 4: 6 to 10 bots Evaluation 3: 11 to 15 bots Evaluation 2: 16 to 20 bots Evaluation 1: 21 or more bots

<Handwriting cassoulet / double line>
For each water-based ballpoint pen, a 20m writing test was conducted using a writing tester to continuously draw a circle on high-quality paper under the conditions of writing angle: 65 °, load: 100 gf, writing speed: 7 cm / sec, rotation: yes. , The occurrence of blurring and double lines was evaluated according to the following evaluation criteria.
Evaluation 5: No double line Evaluation 4: Fewer double lines at the end of writing and writing, double line generation on one side of the overlapping part of the circle Evaluation 3: Fewer double lines at the end of writing and writing, both sides of the overlapping part of the circle Double line generation evaluation 2: Export double line Less evaluation 1: Permanent double line

<Color measurement>
Using a bar coater, RDS No. The water-based ink composition was applied to woodfree paper under the conditions of 9 (20.6 μm) and speed 3 (2.5 ± 0.2 sec / 30 cm).
The handwriting L *, a *, b * and saturation C were measured using a colorimeter (fluorescence spectrophotometer FD-5 (manufactured by Konica Minolta Japan)), and did not contain pigments other than colorants. The color difference ΔE from the handwriting of Comparative Example 7 was obtained.

<Concealment>
Writing on black drawing paper and visually using each water-based ballpoint pen, a V-shape with a side of 15 mm was written on the black drawing paper, the color was visually observed, and the evaluation was made according to the writing evaluation criteria.
○ = Colors are not affected by black drawing paper △ = Colors are slightly affected by black drawing paper × = Colors are affected by black drawing paper

As is clear from the results of each example, the water-based ink composition of the present invention containing the three components of titanium oxide, aluminum oxide, and talc has a drying rate, cap-off property, sedimentation stability, handwriting aesthetics, and writability. Both (cassoulet / double line) and concealing properties are exhibited in a well-balanced manner.
On the other hand, the following can be seen from the results of each comparative example.
Comparative Example 1 in which talc is not used has a particular problem in terms of drying speed.
Comparative Example 2 in which light calcium carbonate is used instead of talc is particularly problematic in terms of drying rate, sedimentation stability and writability (cassoulet / double line).
Comparative Example 3 in which silica is used instead of talc is particularly problematic in terms of cap-off property, sedimentation stability, aesthetics of handwriting, and writability (cassoulet / double line).
Comparative Example 4 in which the amount of aluminum oxide was increased instead of talc is particularly problematic in terms of sedimentation stability and writability (cassoulet / double line).
Comparative Example 5 in which aluminum oxide is not used has a particular problem in terms of drying speed.
Comparative Example 6 in which titanium oxide is not used has a particular problem in terms of concealment.
Comparative Example 7 in which talc is not used is particularly problematic in terms of drying speed and concealing property.

Claims (5)

A water-based ink composition containing titanium oxide, aluminum oxide, and talc. The water-based ink composition according to claim 1, which is used for writing instruments. The water-based ink composition according to claim 1 or 2, wherein the total content of titanium oxide, aluminum oxide and talc is 10 to 40% by mass with respect to the total amount of the water-based ink composition. The water-based ink composition according to any one of claims 1 to 3, wherein the ratio (mass ratio) of the content of titanium oxide to the total content of aluminum oxide and talc satisfies the following formula (1).
Equation (1):
1/99 ≤ Titanium oxide content / (Aluminum oxide content + Talc content) ≤ 5/1 The water-based ink composition according to any one of claims 1 to 4, wherein the content of talc is 2 to 15% by mass with respect to the total amount of the water-based ink composition.