JP2022096633A - Ink composition for writing utensils and writing utensils therewith - Google Patents

Abstract

To provide an ink composition for writing utensils capable of obtaining a calligraphy excellent in concealment of a writing surface and color development in desired color, and, because of capable of obtaining stable ink discharging property, also capable of suppressing generation of line jumps and cassoulet and excellent in brush feeling, excellent in writing property and a writing utensil.SOLUTION: An ink composition for a writing utensil, which is made up of a plate-like titanium oxide, a colorant and a solvent, and a writing utensil using the same.SELECTED DRAWING: None

Description

The present invention relates to an ink composition for writing tools. More specifically, the present invention relates to an ink composition for a writing tool, which is excellent in concealment of a writing surface and color clarity of handwriting. The present invention also relates to a writing tool using the ink composition.

Conventionally, an ink composition for a writing instrument using a white pigment such as titanium oxide or talc has been known in order to obtain a handwriting having a concealing property. Further, it is known that by using a colorant (complementary color pigment) different from the above pigment in combination, handwriting of various colors as well as white can be obtained while having a concealing property. Ink compositions are also being actively studied.

However, when conventional titanium oxide or talc is used, it must be contained in a certain amount or more in order to obtain sufficient hiding power, and titanium oxide or talc has a larger specific gravity than general organic pigments. Therefore, it is very difficult to maintain the dispersion stability of these pigments over time, and further, if they settle, they become hard cakes and cannot be redispersed.
Therefore, attempts have been made to prevent the pigment from settling by modifying the composition with various materials or using a dispersant in combination.
However, although the conventionally reported techniques can slow down the sedimentation rate, it is inevitable that the cake will become a hard cake over a long period of time, and the actual situation is that these measures have not led to sufficient results. Is. Further, measures such as increasing the ink viscosity and developing structural viscosity by using so-called gelling agents and thickeners are being studied. However, even in an ink composition that has taken these countermeasures, the stability over time such as thickening of the ink and the ink ejection property from the pen tip such as a ballpoint pen tip are deteriorated, resulting in line skipping and blurring. In some cases, there were problems with writing performance, such as poor writing quality.

Further, as described above, when it is desired to obtain handwriting of various colors while having a concealing property by using a complementary color pigment in combination, it is necessary to contain a certain amount or more in the conventional titanium oxide or talc. Therefore, the obtained handwriting was affected by titanium oxide, talc, etc., and became a white and light color such as so-called pastel tone. Therefore, it was not possible to obtain a handwriting having a desired color tone and vivid color development. Therefore, it is a big problem to be solved to obtain a handwriting having a desired color tone and excellent color sharpness while having a concealing property.

Japanese Unexamined Patent Publication No. 11-193363 Japanese Unexamined Patent Publication No. 2000-129187

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a handwriting with excellent concealment and color sharpness of the writing surface in a desired color tone, and also to obtain stable ink ejection property, so that line skipping and blurring occur in the handwriting. It is an object of the present invention to provide an ink composition for a writing instrument and a writing instrument using the same, which are excellent in writing performance such as being suppressed and excellent in writing feeling.

The present invention
"1. An ink composition for writing tools, which comprises a plate-shaped titanium oxide, a colorant, and a solvent.
2. 2. The ink composition according to item 1, wherein the content of the plate-shaped titanium oxide is 0.001% by mass or more and 10% by mass or less based on the total mass of the ink composition.
3. 3. The ink composition according to item 1 or 2, wherein the colorant is a pigment and the solvent is water.
4. The ink composition according to any one of Items 1 to 3, further comprising a surfactant.
5. A writing instrument comprising the ink composition according to any one of paragraphs 1 to 4. ".

According to the present invention, it is possible to obtain a handwriting with excellent concealment and color sharpness of the writing surface in a desired color tone, and stable ink ejection property can be obtained. It is possible to provide an ink composition for a writing instrument having excellent writing performance, such as suppressing the occurrence of blurring and having an excellent writing feeling, and a writing instrument using the same.

Hereinafter, embodiments of the present invention will be described in detail. In the present specification, "part", "%", "ratio" and the like indicating the composition are based on mass unless otherwise specified, and the content is a constituent component based on the mass of the ink composition. Is the mass% of.

The ink composition for writing tools according to the present invention (hereinafter, may be referred to as "ink composition" or "composition" in some cases) comprises a plate-shaped titanium oxide, a colorant, and a solvent. Hereinafter, each component constituting the ink composition according to the present invention will be described.

<Plate-shaped titanium oxide>
The ink composition for writing tools according to the present invention comprises plate-shaped titanium oxide.
As the plate-shaped titanium oxide, powder or one previously dispersed in a solvent can be applied.

The plate-shaped titanium oxide of the present invention is titanium oxide having a plate shape, and is a plate-shaped titanium oxide having two main surfaces (the widest surface in the plate-shaped titanium oxide). The shape of the main surface is not particularly limited, and examples thereof include a substantially triangular shape, a substantially quadrangular shape, a substantially pentagonal shape, a substantially hexagonal shape, a substantially seven-sided shape, a substantially octagonal shape, and a substantially circular shape. Further, the plate-shaped titanium oxide includes not only a flat plate-shaped (flat and non-curved plate) but also a curved plate-shaped one and a plate-shaped one having a non-constant thickness. The plate-shaped titanium oxide of the present invention is preferably flat-shaped.

In the present invention, the plate-shaped titanium oxide has a plate-shaped shape as described above. Therefore, when writing on a penetrating surface such as paper or a non-permeable recording medium such as a film using the ink for writing tools according to the present invention, the plate-shaped titanium oxide is placed in parallel with the writing surface. Even with a small amount of addition, it is difficult to create gaps, and a dense concealing layer can be formed. be able to. Further, since the concealing property of the writing surface is excellent even in a small amount, the color tone of the obtained handwriting is not easily affected by the color of the writing surface, and therefore, a handwriting with a desired color tone and vivid color development can be obtained. Further, the plate-shaped titanium oxide tends to be superior in concealing property of the writing surface as compared with talc and kaolin other than titanium oxide which also has a plate-like shape, so that the color of the writing surface is effective. By concealing it in a realistic manner, it is possible to obtain a clear color handwriting with a desired color tone.

Further, the ink composition of the present application contains a colorant together with the plate-shaped titanium oxide, but the obtained handwriting is such that the plate-shaped titanium oxide having a relatively large specific density is placed in the lower part of the handwriting and compared. Colorants with a light target density are unevenly distributed in the upper part of the handwriting. At this time, as described above, the plate-shaped titanium oxide is placed in parallel with the writing surface due to its shape, and a dense concealing layer can be formed. Therefore, the plate-shaped titanium oxide can be placed on the dense concealing layer of titanium oxide. In addition, colorants will be present. For this reason, compared to the case where conventional titanium oxide having a substantially spherical shape is used, it becomes difficult for titanium oxide and the colorant to coexist in the handwriting. Therefore, the obtained handwriting is not easily affected by the titanium oxide, the color tone becomes whiter and lighter than the original color tone of the colorant, and the dense layer of the concealing layer of the titanium oxide covers the handwriting. It is less susceptible to the influence of the color of the writing surface, and it is possible to obtain a handwriting with excellent color vividness with the original color tone of the desired colorant.

Further, since the ink composition for writing utensils according to the present invention contains plate-shaped titanium oxide, when it is used for a ballpoint pen using a ballpoint pen tip as a pen tip, it also has an effect of preventing sagging (suppressing ink leakage from the pen tip). Excellent.
The reason for this is not clear, but the plate-like titanium oxide has a plate-like particle shape, and the plate-like primary particles are oriented in parallel with each other and are overlapped with each other. By forming secondary particles (plate-shaped titanium oxide having a particle morphology of a laminated structure), and by forming tertiary aggregated particles in which the fragmentary primary particles are tertiary aggregated in the form of leaf-like secondary particles, the ball and the tip of the chip It is thought that this is to prevent ink leakage by causing a physical obstacle in the gap between the inner wall and the inner wall.
Since the leaf-like secondary particles and tertiary agglomerated particles have a structure formed by weak agglomeration, the agglomerated structure is crushed by a physical action such as rotation of a ball at the time of writing, so that the ink fluidity at the time of writing It is possible to write well without disturbing the writing, and it is possible to achieve both prevention of sagging and writing performance.

Further, since the ink composition for writing tools according to the present invention contains plate-shaped titanium oxide, as described above, when writing on a recording medium such as paper or film, titanium oxide is parallel to the writing surface. It is placed and it is difficult to create gaps even with a small amount of addition, and a dense concealing layer can be formed. Therefore, the amount of plate-shaped titanium oxide added can be extremely reduced as compared with the conventional ink for writing tools using titanium oxide which is substantially spherical. Therefore, even when the writing instrument is left unused for a long period of time, the plate-shaped titanium oxide does not easily settle on the bottom surface or the wall surface of the ink tank of the writing instrument due to its own weight, and is excellent in storage stability.
Further, even when the plate-shaped titanium oxide is settled on the bottom surface or the wall surface of the ink tank of the writing instrument, the amount of the plate-shaped titanium oxide added is extremely small, so that the amount of the plate-shaped titanium oxide is small even when the plate-shaped titanium oxide is settled or deposited. Since its own weight is light and the degree of aggregation is small, it is difficult to make a hard cake. Therefore, it is possible to obtain an ink composition having excellent redispersibility, such as being easily dispersed again by stirring the ink. When the conventional substantially spherical titanium oxide is used, it is necessary to add a certain amount or more of titanium oxide in order to obtain the required concealing property. When titanium oxide is added in the required amount in the past, the viscosity tends to increase, the ink fluidity is impaired, which reduces the writing quality, and the ink's followability is insufficient, which tends to cause line blemishes and blurring, and the pen tip. There was a tendency for problems to occur in the dry-up resistance of the ink. Further, since titanium oxide is a hard inorganic pigment, it tends to accelerate the wear of the ball seat when used in a ballpoint pen. When the plate-shaped titanium oxide of the present invention is used, the solid content can be suppressed to be extremely low as compared with the conventional one, so that various performances, which have been a problem in the past, can be improved.
From the above, the ink composition of the present application is superior in concealment as compared with the conventional ink composition using titanium oxide because the plate-shaped titanium oxide is hard to settle and has good redispersibility even when aggregated. It tends to keep the ink viscosity low while obtaining the property and color development property, and it is easy to improve the ink ejection property from the pen tip. Excellent. Further, the ink composition has excellent writeability such as dry-up resistance and abrasion resistance.

Further, as described above, the writing tool ink composition according to the present invention can significantly reduce the amount of plate-shaped titanium oxide added as compared with the conventional writing tool ink using titanium oxide. Therefore, particularly when the ballpoint pen tip is used for a ballpoint pen with a pen tip, a rough feeling is less likely to occur during writing, and wear of the ballpoint pen tip can be suppressed. Therefore, it is possible to maintain the same excellent writing feeling as in the initial stage for a long period of time.

Further, in the ink composition for a writing tool according to the present invention, when writing on paper or the like, plate-shaped titanium oxide is placed in parallel with the paper surface due to its particle shape. Therefore, since the plate-shaped titanium oxide does not scratch the paper surface even when overwriting, it is possible to write without scraping the paper surface.

The average particle size of the plate-shaped titanium oxide is preferably 1 μm to 50 μm, and more preferably 5 μm to 40 μm. If the average particle size of the plate-shaped titanium oxide is within the above numerical range, ink can be satisfactorily ejected from a pen tip such as a ballpoint pen tip, a fiber bundle, or a porous body, the writing property is good, and the concealing property is further improved. It is possible to obtain a handwriting with excellent color development. Considering the improvement of the above effect, it is particularly preferably 10 μm to 35 μm.
The average thickness of the plate-shaped titanium oxide is preferably 0.001 μm to 10 μm, and more preferably 0.005 μm to 5 μm. If the average thickness of the plate-shaped titanium oxide is within the above numerical range, the ink can be stably ejected from the pen tip such as a ballpoint pen tip, a fiber bundle, or a porous body, and the writing performance is excellent, but the handwriting is good. Can be obtained. Considering the improvement of the above effect, it is more preferably 0.005 μm to 2 μm, and particularly preferably 0.01 μm to 1 μm.
The aspect ratio (average particle size / average thickness) of the plate-shaped titanium oxide is preferably 2 or more, more preferably 10 or more, more preferably 50 or more, and more preferably 100 or more. Is even more preferable. When the aspect ratio is within the range of the above numerical values, it is easy to obtain a handwriting having excellent concealing property and color developing property while suppressing the addition amount. In addition, since the ink ejection property from the pen tip can be improved, the occurrence of line skipping and blurring in the handwriting is suppressed, and the writing feeling is also improved, so that more excellent writing property can be obtained. Further, considering the dispersion stability in the ink and the ink ejection property from the pen tip such as a ballpoint pen tip, a fiber bundle, or a porous body, the aspect ratio of the plate-shaped titanium oxide is preferably 500 or less, preferably 400 or less. Is more preferable, and 350 or less is particularly preferable.
In particular, in the present application, it is preferable to use plate-shaped titanium oxide having a specific average particle size and a specific aspect ratio (average particle size / average thickness) as described above, that is, the average particle size is 1 μm or more. It is preferable to use plate-shaped titanium oxide having an aspect ratio (average particle diameter / average thickness) of 2 or more, which is 50 μm. Thereby, the effect obtained by the titanium oxide having a plate-like shape can be sufficiently obtained, and the object of the present invention can be sufficiently achieved.
The average particle size of the plate-shaped titanium oxide means the average value of the maximum length and the minimum length of the distance between two points on the contour line of the main surface.
The average thickness of the plate-shaped titanium oxide is the average value of the thicknesses of a plurality of plate-shaped titanium oxides (the minimum distance between the two main surfaces and the thickness when the flat plate particles are viewed from the side). Say.
As a specific measurement procedure for these, for example, using a scanning electron microscope (SEM), a predetermined number (for example, at least 10 randomly extracted (preferably 20 to 100)) plate-shaped titanium oxides is used. The particle size and thickness of each plate-shaped titanium oxide are determined. Further, a value (particle diameter / thickness) obtained by dividing the particle size of each plate-shaped titanium oxide by the thickness is calculated as the aspect ratio of each plate-shaped titanium oxide. Then, by arithmetically averaging the particle diameter, thickness, and aspect ratio of the predetermined number of plate-shaped titanium oxides, the average particle diameter, average thickness, and average aspect ratio can be obtained.

Further, the plate-shaped titanium oxide used in the present invention preferably has a layered structure, and has a crystal structure in which tens to hundreds of layers of layered crystals in which a TiO ₆ octahedron shares a planar ridge are laminated with water molecules or the like sandwiched between them. It is more preferable to have.
Further, in the present invention, the plate-shaped titanium oxide having a layered structure can be confirmed by powder X-ray diffraction using Cu—Kα characteristic X-rays, and has a Bragg angle of 2θ, 10.0 ± 0.3 °. It is preferable that diffraction peaks due to the layered structure are observed at 19.7 ± 0.3 ° and 29.6 ± 0.3 °.
Since the plate-shaped titanium oxide has a layered structure as described above, when writing on a penetrating surface such as paper or a non-permeable recording medium such as a film using the ink for writing tools according to the present invention, writing is performed. It is easy to improve the hiding power of the surface and the color development of the brush strokes, and it is reduced that the color tone becomes white and lighter than the original color tone of the colorant. This is because it is easy to obtain a handwriting.
Further, the plate-shaped titanium oxide of the present invention is preferably obtained from lepidocrocite-type layered titanium acid in consideration of further improvement of the above effects.

Examples of the plate-shaped titanium oxide that can be used in the present invention include plate-shaped titanium oxide (LPT series) manufactured by Ishihara Sangyo Co., Ltd. and plate-shaped titanium oxide (luxeren silk series) manufactured by Sumitomo Chemical Co., Ltd. ) And so on.

The amount of plate-shaped titanium oxide added to the ink composition for writing tools of the present invention is preferably 0.001% by mass or more and 10% by mass or less based on the total mass of the ink composition. It is more preferably 0.005% by mass or more and 5% by mass or less, further preferably 0.01% by mass or more and less than 5% by mass, and particularly preferably 0.02% by mass or more and 4% by mass or less. Particularly preferably, it is 0.02% by mass or more and 1% by mass or less, and most preferably 0.02% by mass or more and 0.5% by mass or less. When the amount of the plate-shaped titanium oxide added is within the above numerical values, the concealing property of the writing surface and the ink dripping performance can be improved, and the dispersity of the pigment and the ink ejection property can also be improved. Further, the whiteness of titanium oxide is emphasized, and it is possible to suppress the color tone of the handwriting from being changed from the original color tone of the coloring material to a whitish and light color tone, and it is possible to improve the color hiding property of the handwriting. Further, when the amount of the plate-shaped titanium oxide added is within the range of the above numerical values, it is preferable because the concealing property of the writing surface can be sufficiently obtained and the color development property of the handwriting is not affected.

Further, the ink composition according to the present invention contains a plate-shaped titanium oxide and a colorant, and the amount of the plate-shaped titanium oxide added is 1: 0.001 to 1 in terms of mass ratio based on the colorant. It is preferably 1: 1, more preferably 1: 0.002 to 1: 0.7, and particularly preferably 1: 0.003 to 1: 0.2. Since the plate-shaped titanium oxide used in the present invention can obtain concealment with an extremely small amount of addition, the ratio of the colorant to the amount of plate-shaped titanium oxide added can be significantly increased as compared with the conventional case. Within this range, it is possible to prevent the handwriting from becoming thin due to the influence of titanium oxide, and therefore, the obtained handwriting can achieve both vivid color development with a desired color tone and excellent concealment. It also has excellent writability. Further, it is preferable because it is possible to suppress the sedimentation property of titanium oxide having a heavy specific gravity, and to obtain an ink composition having excellent dispersion retention and temporal stability of the pigment.

<Colorant>
The ink composition for writing tools according to the present invention comprises a colorant.
As the colorant, pigments and dyes usually used in ink compositions for writing tools can be used.
The colorant in the present application does not include plate-shaped titanium oxide.

The pigment is not particularly limited as long as it can be dispersed in a solvent. For example, inorganic pigments, organic pigments, processed pigments and the like can be mentioned, and specific examples thereof include carbon black, aniline black, ultramarine, yellow lead, titanium oxide (excluding plate-shaped titanium oxide), iron oxide, phthalocyanine and azo. , Kinaclidene-based, quinophthalone-based, threne-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, aluminum pigments, pearl pigments, fluorescent pigments, phosphorescent pigments and the like. In addition, colored resin particles in which resin particles are colored with a dye or the like, or a colored body in which a coloring material is dispersed in a medium are encapsulated in a shell made of a resin wall film forming substance by a known microencapsulation method or the like. A solid-solubilized microcapsule pigment may be used. Further, as the pigment, an aqueous dispersion pigment product or the like which is finely and stably dispersed in an aqueous medium by using a surfactant or a resin in advance may be used.
The dye is not particularly limited as long as it can be dissolved in a solvent. For example, direct dyes, acid dyes, basic dyes, gold-containing dyes, various salt-forming type dyes and the like can be adopted.
These pigments and dyes can be used alone or in combination of two or more.
Further, in the present application, the color of the colorant does not matter, but considering that the effect of the plate-shaped titanium oxide can be sufficiently obtained, it is preferable to use a colorant exhibiting an achromatic color (excluding white color) or a chromatic color. It is more preferable to use a colorant exhibiting a black color or a chromatic color, and in particular, it is preferable to use a colorant exhibiting a chromatic color.

Among these colorants, it is preferable to use a pigment because it tends to be unevenly distributed on the plate-shaped titanium oxide and can improve the water resistance and light resistance of handwriting.
Further, when writing on a penetrating surface such as paper or a non-permeable recording medium such as a film using the ink composition for writing tools according to the present invention, plate-shaped titanium oxide is placed on the lower part of the handwriting and on the upper part of the handwriting. Since the colorant tends to be unevenly distributed, the colorant preferably has a lighter specific gravity than the plate-shaped titanium oxide, and preferably has a smaller average particle size than the plate-shaped titanium oxide. It becomes easy to obtain a handwriting with excellent color vividness in a desired color tone.
The ratio of the specific gravity of the colorant (the specific gravity of the colorant / the specific density of the plate-shaped titanium oxide) to the specific gravity of the plate-shaped titanium oxide is preferably 0.001 to 0.9, preferably 0.01 to 0.9. Is more preferable, 0.1 to 0.8 is more preferable, and 0.2 to 0.6 is more preferable.
The ratio of the average particle size of the colorant to the average particle size of the plate-shaped titanium oxide (average particle size of the colorant / average particle size of the plate-shaped titanium oxide) is 0.0005 to 5.0. It is preferably 0.001 to 2.0, more preferably 0.001 to 0.5, and even more preferably 0.002 to 0.3.

<Solvent>
As the solvent used in the present invention, the solvent used in the conventional water-based ink composition for writing tools and the oil-based ink composition for writing tools can be used.
Specific examples thereof include water, and the water is not particularly limited, and examples thereof include tap water, ion-exchanged water, ultrafiltration water, and distilled water.
Further, polyhydric alcohol solvents such as polyethylene glycol, ethylene glycol, diethylene glycol, glycerin and propylene glycol, glycol ether solvents such as ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monomethyl ether and propylene glycol monophenyl ether, and further. Also includes alcohol solvents such as methanol, ethanol, isopropyl alcohol and benzyl alcohol.
These solvents can be used alone or in combination of two or more.

Above all, in the present invention, it is preferable to use water or a mixed solvent composed of water and an organic solvent (water-soluble organic solvent) soluble in water, and the dispersion stability of the plate-shaped titanium oxide and the concealment of the writing surface are concealed. The ink composition of the present invention is preferably prepared as a water-based ink composition for writing tools, in consideration of efficiently obtaining the effect of improving the property and the effect of improving the color development of the handwriting.

<Other additives>
The ink composition according to the present invention may contain any additive, if necessary. The additives that can be preferably used are as follows.

<Surfactant>
The ink composition according to the present invention preferably contains a surfactant when prepared as a water-based ink composition for writing tools.
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, etc., and surfactants having an acetylene bond in the structure, fluorosurfactants, silicone-based surfactants, etc. Activators, phosphate ester-based surfactants, fatty acid salts and the like can also be mentioned.
As described above, the plate-shaped titanium oxide can obtain excellent hiding power and color development while suppressing the addition amount as compared with the conventional titanium oxide. Therefore, the ink composition of the present application has excellent ink ejection. The character is obtained and the writing feeling is also excellent. In particular, when it is used for a ballpoint pen, it is excellent because the plate-shaped titanium oxide is discharged in an oriented state as compared with the conventional substantially granular titanium oxide, and therefore the wear of the ball and the ball seat tends to be suppressed. You can get a good writing taste. However, on the other hand, since titanium oxide is also a hard particle, it tends to be a resistance when writing on a recording medium such as paper or a film, and may hinder the rotation of the ball when it rotates. Therefore, when the ink composition of the present application is used for a ballpoint pen, it is preferable to further use a surfactant that also has an effect as a lubricant, whereby the writing quality can be further improved.
As the surfactant, it is preferable to use a phosphate ester-based surfactant and a fatty acid salt, and in particular, it is preferable to use a phosphate ester-based surfactant. This is because the phosphoric acid group of the phosphoric acid ester-based surfactant is adsorbed on a metal such as a ball pen tip or a ball, so that it is easier to obtain lubricity. It is easy to suppress blurring even during dry-up.

Examples of the type of the phosphoric acid ester-based surfactant include styrene phenol-based, nonylphenol-based, lauryl alcohol-based, tridecyl alcohol-based, octylphenol-based, and short-chain alcohol-based. Among these, it is preferable to use a phosphate ester-based surfactant that does not have a phenyl skeleton, because having a phenyl skeleton tends to affect the lubricity due to steric damage.
These phosphoric acid ester-based surfactants can be used alone or in combination of two or more.

In the present invention, the phosphoric acid ester-based surfactant preferably has an HLB value of 5 to 15, more preferably 8 to 14, and particularly preferably 10 to 13. Further, in the present invention, the alkyl group or alkylallyl group of the phosphoric acid ester-based surfactant preferably has 6 to 30 carbon atoms, more preferably 8 to 18 carbon atoms, and more preferably 10 to 14 carbon atoms. Especially preferable. This is because a linear phosphate ester-based surfactant having a specific HLB value or carbon number has excellent writing stability such that good handwriting with improved line skipping and blurring can be stably obtained. This is because the dispersant effect can be synergistically improved together with the other dispersants used in the present invention, and at the same time, a lubricating effect can be obtained.

In the present invention, the HLB value of the phosphate ester-based surfactant means the HLB value of the raw material nonionic surfactant of the phosphate ester-based surfactant, and as a general formula, HLB = 7 + 11. It can be obtained from 7log (Mw / Mo), (Mw: molecular weight of hydrophilic group, Mo: molecular weight of lipophilic group).

Specific examples of the phosphoric acid ester-based surfactant include the Plysurf series (Daiichi Kogyo Seiyaku Co., Ltd.), and the linear alcohol-based phosphoric acid ester-based surfactants include Plysurf A212C and A208B. The same A213B, the same A208F, the same A215C, the same A219B, and the same A208N are mentioned. Examples thereof include A212E and A217E, and examples of the octylphenol system include Plysurf A210G. ..

When a phosphoric acid ester-based surfactant is added, the content thereof is preferably 0.1% by mass to 2.0% by mass, preferably 0.5% by mass to 1.5% by mass, based on the total mass of the ink composition. % Is more preferable.

Specific examples of the fatty acid include linoleic acid and oleic acid, and specific examples include OS soap, NS soap, FR-14, FR-25 (Kao Corporation) and the like.

<Dextrin>
Further, the ink composition according to the present invention preferably contains dextrin when prepared as a water-based ink composition for writing tools.
Dextrin has the effect of forming a film on the pen tip and preventing the evaporation of water in the ink by the film.
Since the ink composition of the present invention contains plate-shaped titanium oxide and the plate-shaped titanium oxide is in a dispersed state without being dissolved in a solvent, the writing tool containing the ink composition of the present invention is for writing. If the tip is left in contact with the atmosphere, the solvent will continue to dry from the gap at the tip of the writing (the gap where the ink is ejected), and the ink inside the tip of the writing will dry and solidify, which is extremely difficult for writing during dry-up. In addition, there was a risk that writing would not be possible again, although there was a remaining amount of ink due to the occurrence of brush stroke blurring and the clogging of the ink flow path.
In particular, when the ink composition according to the present invention is used for a ballpoint pen, when the tip of the writing is dried, titanium oxide is a hard particle, so that the rotation of the ball is likely to be hindered and the ball is difficult to rotate. Writing also tends to be inferior. Therefore, it is preferable that the ink composition of the present application has improved dry-up resistance in order to obtain excellent handwriting. As described above, dextrin forms a film on the pen tip and has the effect of preventing evaporation of the solvent in the ink by the film. Therefore, it is very effective to use dextrin in the ink composition of the present invention. be. In particular, in the ink composition of the present invention, the amount of titanium oxide added can be extremely reduced as compared with the conventional substantially spherical titanium oxide by using plate-shaped titanium oxide, and excellent dry resistance can be achieved by further combining dextrin. It is possible to obtain an up property.
Dextrin is a general term for substances in which several α-glucoses are polymerized by glycosidic bonds, and is a kind of dietary fiber, which is obtained by hydrolysis of starch.

Further, dextrin tends to be soluble and stable by using a glycol solvent. Therefore, when dextrin is used, it is preferable to use a glycol-based solvent as the water-soluble organic solvent. In addition, since the glycol-based solvent also has a hygroscopic effect, by containing it, the ink at the tip of writing can soften the solidification of the film formed by dextrin during drying and improve the writing performance at the time of writing. ,preferable.

The content of dextrin is preferably 0.1 to 5.0% by mass with respect to the total amount of the ink composition. This is because if it is less than 0.1% by mass, the effect of dry-up resistance tends not to be sufficiently obtained, and if it exceeds 5.0% by mass, it tends to be difficult to dissolve in the ink. Considering more solubility in the ink, 0.1 to 3.0% by mass is preferable, and more considering dry-up performance, 1.0 to 3.0% by mass is most preferable.

The weight average molecular weight of dextrin is more preferably 5000 to 100,000. When the weight average molecular weight exceeds 100,000, the film formed on the tip of the chip is hard, and the handwriting tends to be easily blurred during writing during dry-up. On the other hand, when the weight average molecular weight is less than 5,000, the moisture absorption is high. 5000 to 100,000 is more preferable because the coating tends to be soft at the tip of the chip, evaporation of the solvent cannot be sufficiently suppressed, and the ink dries and solidifies, causing inability to write. Further, when the weight average molecular weight is smaller than 20000, the film tends to be thin, and therefore, the weight average molecular weight is most preferably 20000 to 100,000.

<Ink viscosity modifier>
Further, when the ink composition according to the present invention is prepared as a water-based ink composition for writing tools, it is preferable that the ink composition contains an ink viscosity adjusting agent.
This is because when the ink composition according to the present invention is used for a writing tool, it can be expected to have an effect of preventing sedimentation of plate-shaped titanium oxide particles and facilitating maintaining a uniform and good dispersed state. When used in a ballpoint pen, it is preferable to use a shear thinning agent as the ink viscosity adjusting agent. By using a shear-reducing viscosity-imparting agent, the viscosity of the ink composition when standing is kept high, it is easy to maintain a uniform and good dispersed state, and while preventing the settling of plate-shaped titanium oxide particles and the like, At the time of writing, the shearing force due to the rotation of the ball at the tip of the tip is applied to the ink composition, the viscosity of the ink composition is lowered, good ink ejection property is brought about, and it is possible to obtain a brush with good color development without bleeding. Is. In particular, the plate-shaped titanium oxide of the present invention has a plate-like shape unlike the conventional titanium oxide having a substantially spherical shape, so that it efficiently receives the viscous resistance of the ink and tends to have a more excellent effect of suppressing sedimentation. Therefore, in the ink composition of the present invention, it is preferable to use a shear-reducing viscosity-imparting agent together with the plate-shaped titanium oxide.

Examples of the shear thinning agent include cross-linked acrylic acid polymers, polysaccharides such as xanthan gum, welan gum, succinoglycan, guar gum, locust bean gum, λ-carrageenan, cellulose derivatives, and daiyutan gum, and associated thickening. Agents are mentioned. Of these, considering the dispersion stability of plate-shaped titanium oxide, it is preferable to use a polysaccharide, and further, when the ink composition according to the present invention is used with a ballpoint pen, excellent dispersion stability and good handwriting are used. It is preferable to use xanthan gum or succinoglycan, which is easy to obtain, and it is particularly preferable to use xanthan gum.
These shear thinning agents can be used alone or in combination of two or more.

In the present invention, when the ink viscosity adjusting agent is contained, the ink viscosity of the ink composition of the present invention is preferably 100 to 5000 mPa · s at a shear rate of 1.92 sec ^-1 in an environment of 20 ° C. When the ink viscosity is within the above numerical range, the ink fluidity and dispersion stability are excellent, the ink ejection property is good, and a good ink stroke without blurring or bleeding can be obtained.

<Organic resin particles>
Further, the ink composition according to the present invention preferably contains organic resin particles.
By using the organic resin particles, the organic resin particles enter between the ball and the ball seat, and not only the writing quality is improved by the cushioning effect, but also the effect of suppressing the wear of the ball seat and the effect of suppressing ink leakage from the pen tip are achieved. Can be granted. In particular, when the ink composition according to the present invention is used for a ballpoint pen, as described above, the plate-shaped titanium oxide is ejected in an oriented state, so that the ink composition is more like a ball than the conventional titanium oxide having a substantially spherical shape. It tends to suppress the wear of the ball seat, but on the other hand, since titanium oxide is a hard particle, it may hinder the ball rotation during writing. Therefore, by further containing the organic resin particles, the interaction of the cushioning effect of the organic resin particles works, the wear suppression of the ball seat is improved, and there is a tendency that a better writing taste can be continuously obtained. be. Therefore, it is effective and preferable to further use the organic resin particles in the ink composition according to the present invention.
Further, in the ink composition according to the present invention, as described above, the plate-shaped titanium oxide forms aggregated particles, which causes a physical obstacle in the gap between the ball and the inner wall of the tip of the chip, resulting in ink leakage. However, by further using the organic resin particles, the organic resin particles can fill the gaps of the aggregates formed due to the plate-like titanium oxide having a plate-like shape. Therefore, by using the plate-shaped titanium oxide and the organic resin particles, the two interactions work, and the ink leakage suppressing effect can be further obtained. Therefore, also in this respect, it is effective and preferable that the ink composition according to the present invention further contains organic resin particles.
Specifically, the organic resin particles include olefin resin particles such as polyethylene resin and polypropylene resin, and chemical structures such as melamine / formaldehyde resin, benzoguanamine / formaldehyde resin, benzoguanamine / melamine / formaldehyde resin, urea formaldehyde resin, and nylon resin. Examples thereof include nitrogen-containing resin particles containing a nitrogen atom, acrylic resin particles, styrene resin particles, epoxy resin particles, urethane resin particles, cellulose resin particles and the like. Among them, it is preferable to use olefin-based resin particles and nitrogen-containing resin particles in consideration of the fact that the ink leakage suppressing effect can be easily obtained by the interaction with the plate-shaped titanium oxide. Particles are preferred.
These organic resin particles can be used alone or in combination of two or more.

Examples of the material of the olefin resin particles include polyolefins such as polyethylene, polypropylene and polybutene, and mixtures thereof. Among these, polyethylene is preferably used in consideration of the improvement of writing quality and the effect of suppressing ink leakage from the pen tip. Specifically, low-density polyethylene, high-density polyethylene, low-molecular-weight polyethylene, modified polyethylene, and modified polyethylene are used. Examples include high-density polyethylene. Among them, low-density polyethylene, low-molecular-weight polyethylene, and modified polyethylene are preferable in consideration of the effect of suppressing ink leakage. In particular, low-density polyethylene has a lower melting point than other types of polyethylene and has a soft property, so that polyethylene particles adhere to it. Low-density polyethylene is preferable because it is easy to make, gaps between particles are hard to occur, and ink is hard to leak. Further, low-density polyethylene is soft and can be suitably used for improving writing quality. The olefin-based resin particles may contain a material other than the polyolefin, if necessary.

Further, the ink composition according to the present invention is a preservative, a wetting agent, an antifoaming agent, a rust preventive agent, a pH adjuster, a bubble suppressant, and a bubble absorber, if necessary, as long as the effects of the present invention are not impaired. , Various additives such as fixing agents can be contained.

Examples of the pH adjuster 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, and inks. Considering the stability over time of the composition, it is preferable to use a basic organic compound, and more considering it, it is preferable to use a weakly basic triethanolamine. These pH regulators may be used as one type or a mixture of two or more types.

Examples of the rust preventive include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, saponin, dialkylthiourea and the like.

Preservatives include phenol, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, 2-pyridinethiol-1-. Examples thereof include sodium oxide, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one and the like.

Examples of the chelating agent include ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), glycol etherdiaminetetraacetic acid (GEDTA), nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), and dihydroxyethylglycine (DHEG). ), Diethylenetriaminetetraacetic acid (DTPA), triethylenetetraminehexacetic acid (TTHA) and alkali metal salts thereof, ammonium salts or amine salts thereof.

Further, in the present invention, in order to further improve the effect of suppressing water evaporation from the pen tip, a moisturizer such as N, N, N-trialkyl amino acids such as urea, sorbitol and trimethylglycine, and hyaluronic acids may be used. do not have.

Further, as the fixing agent, an acrylic resin, a urethane resin, a styrene-butadiene resin, a polyester resin, a vinyl acetate resin, or the like can be added.

The viscosity of the ink composition according to the present invention can be set to an appropriate viscosity for the writing tool used.
When the ink composition of the present invention is used for a ballpoint pen or the like using a shear thinning agent, the viscosity of the ink composition is preferably 100 mPa · s to 5000 mPa · s, and 1000 mPa · s to 3500 mPa · s. -S is more preferable, and 1500 mPa · s to 3000 mPa · s is even more preferable. When the viscosity of the ink composition is within the above numerical range, the dispersion stability of the plate-shaped titanium oxide is easily maintained over time, the ink dispersion stability is excellent, and the ink ejection property from the ballpoint pen tip is good. It is possible to obtain excellent handwriting, and further, it is possible to obtain a handwriting having excellent handwriting concealment and color development.
The ink viscosity in this case can be measured at a shear rate of 1.92 (sec ^-1 ) in a 20 ° C. environment using a DV-II viscometer (CPE-42 rotor) manufactured by Brookfield.
When the ink composition of the present invention is used for a marking pen or the like, the viscosity is preferably 1 mPa · s to 50 mPa · s, more preferably 1 mPa · s to 20 mPa · s, and 2 mPa · s. -It is more preferably s to 10 mPa · s. Since the ink composition of the present invention uses plate-shaped titanium oxide, it is possible to suppress the amount of the titanium oxide added to obtain a brush with excellent hiding power and color vividness, and to obtain plate-shaped titanium oxide. The ink composition of the present invention used can be easily adjusted to a low-viscosity ink having a viscosity range as described above.
The ink viscosity in this case can be measured using a B-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd., using a BL adapter) under a condition of 20 ° C. and a rotation speed of 30 rpm.

The pH of the ink composition according to the present invention is preferably pH 6 to pH 10, and more preferably pH 7 to pH 9. When the pH of the ink composition is within the above numerical range, the ink is not discolored or the ink viscosity is not increased, and the ink can be used without any influence. In the present invention, the pH value can be measured at 20 ° C. by, for example, an IM-40S type pH meter (manufactured by DKK-TOA CORPORATION).

The ink composition according to the present invention can be produced by any conventionally known method. Specifically, each of the above components can be blended in a required amount and mixed with various stirrers such as propeller stirring, homodisper, or homomixer, and various dispersers such as bead mills to produce the product.

<Stationery>
The ink composition according to the present invention can be used for writing tools such as marking pens and ballpoint pens using a pen nib such as a fiber tip, felt tip, plastic tip or a ballpoint pen tip, and a fountain pen using a metal pen tip. can.

The writing tool on which the ink composition of the present invention can be used may be one that is directly filled with the ink composition, and includes an ink container or an ink occlusion body that can be filled with the ink composition. It may be a thing. Further, in order to redistribute the plate-shaped titanium oxide particles and the like, the ink container may include a stirring body such as a stirring ball for stirring the ink.

Further, the infestation mechanism of the pen tip in a writing tool to which the ink composition of the present invention can be used is not particularly limited, and a cap type having a cap covering the pen tip, a knock type, a rotary type, a slide type, or the like is used. There is a haunting type that can accommodate the pen tip in the cylinder. As described above, when the plate-shaped titanium oxide is used for a ballpoint pen using a ballpoint pen tip as a pen tip, it has excellent ink ejection properties, but also has an effect of preventing dripping (suppressing ink leakage from the pen tip). The ink composition according to the present invention can be effectively used for a haunting writing tool that needs to be considered for suppression, particularly a haunting ballpoint pen.

Further, the ink supply mechanism in the writing tool is not particularly limited, and for example, (1) a mechanism in which an ink guide core made of a fiber bundle or the like is provided as an ink flow rate adjusting member and the ink composition is supplied to the pen tip. 2) A flow control member having a comb groove-shaped ink holding portion is provided, and a mechanism for supplying the ink composition to the pen tip by interposing the flow control member is provided. Examples thereof include a mechanism for supplying the pen tip, and (4) a mechanism for directly supplying the ink composition to the pen tip from an ink container or a shaft tube provided with the pen tip.

In one embodiment, the writing tool is a ballpoint pen, preferably a ballpoint pen provided with an ink backflow preventive body.

The structure and shape of the ballpoint pen itself are not particularly limited as the ballpoint pen. It has a ballpoint pen having a structure in which an ink flow rate adjusting member and a chip are connected to each other, and an ink storage tube filled with ink in a barrel, and the ink storage tube communicates with a chip having a ball attached to the tip. Further, a ballpoint pen in which a liquid stopper for preventing backflow is in close contact with the end face of the ink can be exemplified.

Generally, the ball is made of cemented carbide, stainless steel, ruby, ceramic, resin, rubber or the like. Further, a ball diameter of generally 0.2 to 3.0 mm, preferably 0.25 to 1.5 mm, and more preferably 0.25 to 1.0 mm can be applied.

When the ink composition according to the present invention is used for a ballpoint pen, it is preferable that the ball diameter and the ink consumption satisfy a specific relationship, and the ink consumption per 100 m of the ballpoint pen is A (mg) and the ball diameter is B. When (mm) is set, the relationship of 100 ≦ A / B ≦ 800 is preferable, and the relationship of 200 ≦ A / B ≦ 700 is preferable.
In the ink composition of the present application using the plate-shaped titanium oxide, it is easy to set a specific relationship between the ball diameter and the ink consumption within the above range, thereby improving the ink fluidity and the ink from an excellent pen tip. Dischargeability is obtained, and it becomes possible to obtain more handwriting with excellent color development and concealment properties.

Regarding the amount of ink consumed, spiral using 5 test samples at a writing speed of 4 m / min under the conditions of 20 ° C, writing paper JIS P3201 writing angle 70 °, and writing load 100 g. A written test is performed, and the average value of the ink consumption per 100 m is defined as the ink consumption per 100 m.

The movable amount (clearance) of the ball in the ballpoint pen tip in the vertical axis direction is preferably 20 to 60 μm, preferably 30 to 50 μm at the time of manufacturing or starting the use of the ballpoint pen. Within the above range, the ejection property of the plate-shaped titanium oxide from the pen tip can be improved, good ink ejection property can be obtained, and handwriting with sufficient hiding property can be easily obtained. Further, the effect of preventing the plate-shaped titanium oxide from dripping (suppressing ink leakage from the pen tip) can be sufficiently achieved. Further, if the clearance is within the above range, the above ratio A / B can be easily adjusted.

The movable amount (clearance) of the ball of the ballpoint pen tip in the vertical axis direction indicates the distance that the ball can move in the vertical axis direction of the ballpoint pen tip body. Here, the movable amount generally tends to increase with use because the ball and the ball seat are worn by use. The movable amount is related to the ink ejection amount. Therefore, in general, the movable amount at the time of manufacturing or the start of use of the ballpoint pen is set within the above range, and therefore, in order to achieve stable writing characteristics, until the end of use of the ballpoint pen, within the above range. It is preferable to have.

In one embodiment, the writing instrument is a marking pen, and the pen tip is not particularly limited, and may be, for example, a fiber tip, a felt tip, a plastic tip, or the like, and the shape thereof may be bullet-shaped, chisel-shaped, or the like. It may be a brush pen type or the like.

An ink composition for writing tools was obtained by the following compounding composition and method.
(Example 1)
・ Plate-shaped titanium oxide 0.5% by mass
(Manufactured by Ishihara Sangyo Co., Ltd., trade name: LPT-106, average particle diameter 10 to 35 μm, average thickness 0.1 μm, average aspect ratio 100 to 350)
-Colorant 6.5% by mass
(Magenta color pigment dispersion (containing 20% pigment, 4% water-soluble acrylic resin), magenta color pigment: Pigment Red 122, average particle size 0.12 μm, specific gravity 1.5 g / cm ³ )
-Colorant 23.5% by mass
(Yellow pigment pigment dispersion (containing 20% pigment, 4% water-soluble acrylic resin), yellow pigment: Pigment Yellow 110, average particle size 0.16 μm, specific gravity 1.8 g / cm ³ )
・ Phosphoric acid ester-based surfactant 1.0% by mass
(Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Product name: Prisurf A215C)
・ Dextrin 1.5% by mass
(Made by Sanwa Cornstarch Co., Ltd., Product name: Sandeck # 70FN)
・ Shear thinning agent 18.5% by mass
(Xanthan gum, trade name: Keldent, solid content 2.6%)
-Organic resin particles 0.25% by mass
(Low density polyethylene resin particles, manufactured by Mitsui Chemicals, Inc., trade name: Chemipearl M200, solid content 40%, average particle diameter: 6 μm)
・ Ion-exchanged water balance

Each component except the shear thinning agent was mixed and stirred with a disper to prepare a base ink. Then, while heating the base ink produced above, a shear thinning agent was added and sufficiently mixed and stirred using a homogenizer stirrer until a uniform state was obtained to obtain the ink composition of Example 1. ..
Further, as a result of measuring the pH value of the ink composition at 20 ° C. using an IM-40S type pH meter (manufactured by DKK-TOA CORPORATION), the pH value was 8.6. In addition, the viscosity of the obtained ink composition was measured by an E-type rotary viscometer (model: DV-II + Pro, rotor: CPE-42, manufactured by Brookfield) at a shear rate of 1.92 sec ^-1 in a 20 ° C environment. When the ink viscosity was measured under the condition of rotation speed 0.5 rpm), it was 2100 mPa · s.

The trade name LPT-106 used as the plate-shaped titanium oxide is obtained from the lepidoclosite-type layered titanium acid, and the layered crystals in which the TiO ₆ octahedron shares the ridge in a plane sandwiches water molecules and the like. It was a layered structure in which dozens to hundreds of layers were laminated. In addition, by powder X-ray diffraction using Cu-Kα characteristic X-ray, the layers are layered at 10.0 ± 0.3 °, 19.7 ± 0.3 °, and 29.6 ± 0.3 ° at Bragg angle 2θ. Diffraction peaks due to the structure were observed.

(Examples 2 to 9, Comparative Examples 1 to 3)
Ink compositions for writing tools of Examples 2 to 9 and Comparative Examples 1 to 3 were obtained by the same method as in Example 1 except that the ink compositions were blended as shown in Tables 1 and 2.

The details of the materials used in the comparative example are as follows.
・ Approximately spherical titanium oxide
(Manufactured by Ishihara Sangyo Co., Ltd., trade name: CR-50, rutile type, average particle size: 0.25 μm)

A ballpoint pen tip (vertical direction of the ball) in which the ink compositions (1.0 g) obtained in Examples 1 to 9 and Comparative Examples 1 to 3 are rotatably held by a cemented carbide ball having a diameter of 0.5 mm. A refill was prepared by filling the inside of an ink container having a movement amount (clearance) of 25 μm) at the tip, and this refill was attached to a gel ink ballpoint pen (trade name: JUICE) manufactured by Pilot Corporation to obtain a ballpoint pen. rice field. The obtained ballpoint pen was used as a test ballpoint pen, and the following tests were performed.
The ink consumption per 100 m of the test ballpoint pen using the ink composition of Example 1 was 140 mg.

(Evaluation of concealment of the written surface)
A part of the writing test paper was filled with the above-mentioned test ballpoint pen, and the concealing property of the obtained handwriting on the writing surface was visually observed. A film (yellow, made of polyester) was used as the writing test paper.
A: The handwriting sufficiently conceals the surface to be written, and a good handwriting is obtained.
B: The handwriting conceals the writing surface, but it is not sufficient, and the color of the writing surface is slightly transparent.
C: The handwriting is visible, but the writing surface is hardly concealed, and the color of the writing surface is transparent.
D: The handwriting cannot be visually recognized and the writing surface is not concealed at all.

(Evaluation of handwriting color sharpness)
Writing was performed on the writing test paper with the above-mentioned test ballpoint pen, and the color tone and color vividness of the obtained handwriting were visually observed. JIS P3201 and writing paper A were used as the writing test paper.
A: The handwriting has a desired color tone and is extremely vivid.
B: The handwriting is slightly whiter and lighter than the desired color tone, but the color is vivid.
C: The handwriting is slightly whiter and lighter than the desired color tone, and the color development is slightly inferior in sharpness.
D: The handwriting was whiter and lighter than the desired color tone, and was inferior in sharpness.

(Evaluation of writeability (1) (presence or absence of line tobikasure))
A spiral circle was continuously written on the writing test paper with the above-mentioned test ballpoint pen, and the state of the obtained handwriting was visually observed. JIS P3201 and writing paper A were used as the writing test paper.
A: Good handwriting was obtained with good color development and no line skipping or blurring.
B: Although slight line skipping and blurring were confirmed in the handwriting, a handwriting with good color development was obtained.
C: Line skipping and blurring were confirmed in the handwriting, but it was at a level where there was no problem in practical use.
D: Many line skips and blurs were confirmed in the handwriting, good handwriting could not be obtained, and some handwriting became impossible.

(Evaluation of writeability (2) (feeling of writing))
A spiral circle was continuously written on the writing test paper with the above-mentioned test ballpoint pen, and the state of the obtained handwriting was visually observed. JIS P3201 and writing paper A were used as the writing test paper.
A: The writing taste was extremely smooth.
B: The writing taste was smooth.
C: I felt the writing taste was a little heavy, but it was at a level where there was no problem in practical use.
D: The writing taste was heavy and slippery.

A ballpoint pen tip (vertical ball) in which the ink compositions (1.0 g) obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were rotatably held by a cemented carbide ball having a diameter of 0.5 mm. A refill filled inside an ink container having an axial movement amount (clearance) of 40 μm) is prepared, and this refill is attached to a gel ink ballpoint pen (trade name: JUICE) manufactured by Pilot Corporation. Got The obtained ballpoint pen was used as a test ballpoint pen, and the concealing property of the writing surface, the sharpness of handwriting color development, and the writing property were evaluated. As a result, the same results as in Tables 1 and 2 were obtained.

The ink composition for writing tools of the present invention can be used for various writing tools such as fountain pens, ballpoint pens, brush pens, calligraphy pens, and various markers. Further, it can be suitably used as a writing tool containing the ink composition.

Claims (5)

An ink composition for writing tools, which comprises a plate-shaped titanium oxide, a colorant, and a solvent. The ink composition according to claim 1, wherein the content of the plate-shaped titanium oxide is 0.001% by mass or more and 10% by mass or less based on the total mass of the ink composition. The ink composition according to claim 1 or 2, wherein the colorant is a pigment and the solvent is water. The ink composition according to any one of claims 1 to 3, further comprising a surfactant. A writing instrument comprising the ink composition according to any one of claims 1 to 4.