JP6824033B2 - Water-based ballpoint pen - Google Patents

Description

The present invention relates to an ink composition for a water-based ballpoint pen, and more particularly to an ink composition for a water-based ballpoint pen having good handwriting drying property and writing taste, and a water-based ballpoint pen using the same.

The ink composition for a water-based ballpoint pen is an ink composition in which the main solvent is water. For this reason, if the pen tip is exposed to the atmosphere for a while, water, which is the main solvent, evaporates from the pen tip, the ink viscosity becomes high, the brush strokes become faint, and the water evaporates and the ink progresses. Has been confirmed to dry and solidify, and the ink flow path of the writing instrument is clogged, making writing impossible. In particular, when it is used for a haunting type ballpoint pen, this phenomenon is remarkably likely to occur because the pen tip is always exposed to the atmosphere. Therefore, in order to suppress the evaporation of water in the ink composition, it is common practice to add a polyhydric alcohol solvent such as glycerin or ethylene glycol as a moisturizer. However, although it tends to suppress the evaporation of water from the ink, the obtained handwriting requires time to completely dry, so if you touch the undried handwriting, the writing surface may become dirty. It has problems such as the handwriting itself becoming dirty.
In order to solve these problems, Patent Document 1 discloses an ink composition containing 1,4-cyclohexanedimethanol and one or more of ethyl alcohol, n-propyl alcohol and isopropyl alcohol. Patent Document 2 discloses an ink composition containing dioctyl sulfosuccinate, and Patent Document 3 discloses an ink composition containing a fluorine-based surfactant. Many ink compositions have been proposed in which the surface tension of the composition is lowered to improve the permeability to the paper surface.

However, although the ink composition of Patent Document 1 improves the drying property of handwriting, it has a problem of stability over time because it has a peculiar offensive odor of an alcohol solvent and is highly volatile. Further, in the ink composition of Patent Document 2, although the dryness of the handwriting tends to be improved, it cannot be said that it is sufficient, and it is difficult to obtain a good handwriting.

Further, when an ink composition such as Patent Documents 2 and 3 is used for a ballpoint pen, the permeability to the paper surface is improved to some extent, but further improvement in handwriting drying property and improvement in lubricity are desired. Further, the wettability to the ballpoint pen tip is also improved, and the ink easily leaks from the pen tip, so that the ink composition for a water-based ballpoint pen is not sufficiently satisfactory.

In addition, recently, ballpoint pens are often arranged in a display case, and in the case of a ballpoint pen in a cap-off state such as a haunting ballpoint pen, when the ballpoint pen tip is returned to the display case with the ballpoint pen protruding, the ball and tip A gap is created between the tip and the inner wall, ink drips from the gap, ink leaks, and the display case is soiled, and other ballpoint pens inside the case are also prone to becoming dirty. Is desired at the same time.

Japanese Unexamined Patent Publication No. 2000-319570 Japanese Unexamined Patent Publication No. 2005-238672 Japanese Unexamined Patent Publication No. 2004-224892

The present invention is to obtain an ink composition for a water-based ballpoint pen that improves handwriting drying property and further improves writing quality, and a water-based ballpoint pen using the same.

In order to solve the above problems, the present invention
"1. An ink composition for an aqueous ballpoint pen containing water, a colorant, and a silicone-based surfactant, wherein the silicone-based surfactant has the following general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula). An ink composition for a water-based ballpoint pen, characterized in that one or more of them are selected from 3).

2. 2. The ink composition for an aqueous ballpoint pen according to Item 1, wherein the silicone-based surfactant has a weight average molecular weight of 500 to 3000.
3. 3. The ink composition for an aqueous ballpoint pen according to item (1) or item (2), wherein the colorant is a pigment.
4. The water-based ballpoint pen ink composition according to any one of items 1 to 3, wherein the water-based ballpoint pen ink composition contains organic resin particles.
5. The ink composition for an aqueous ballpoint pen according to Item 4, wherein the organic resin particles are an olefin resin.
6. The ink composition for an aqueous ballpoint pen according to Item 4, wherein the organic resin particles are an olefin resin. ".

The present invention provides an ink composition for a water-based ballpoint pen that improves handwriting drying property by improving the permeability to a paper surface and further improves the writing quality by improving lubricity, and a water-based ballpoint pen using the same. I was able to get it.

The feature of the present invention is that one or more silicone-based surfactants represented by structural formulas such as the following general formulas (Chemical Formula 1), (Chemical Formula 2), and (Chemical Formula 3) are selected as specific silicone-based surfactants. An ink composition for a water-based ballpoint pen, which is characterized in that it is used, and a water-based ballpoint pen using the same.

<Silicone-based surfactant>
As the silicone-based surfactant used in the present invention, one or more of the structural formulas of the general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3) can be selected and used to obtain the ink for the written paper surface. By improving the permeability, the dryness of handwriting can be improved. Further, by improving the lubricity, the writing quality can be improved.

Among the silicone-based surfactants, it is preferable to use the general formulas (Chemical Formula 1) and (Chemical Formula 2), in which the ethylene oxide group or the propylene oxide group in the structure of the silicone-based surfactant is hydrophilic. This is to make the balance of hydrophobicity suitable. Here, if the hydrophilicity of the silicone-based surfactant is too high, the solubility in the ink becomes too high, and it is difficult to quickly arrange the surfactant molecules with respect to the gas-liquid interface, and the permeability tends to be difficult to improve. If the hydrophobicity of the silicone-based surfactant is too high, the solubility in the ink becomes too low, the permeability is difficult to improve, and the stability to the ink tends to be inferior due to separation or the like.
Since the silicone-based surfactants of the general formulas (Chemical formula 1) and (Chemical formula 2) have an ethylene oxide group or a propylene oxide group in the structure, the balance between hydrophilicity and hydrophobicity is suitable, and the surfactant is stable in the ink. However, since the activator molecules are easily arranged at the gas-liquid interface, the surface tension of the ink is quickly controlled during writing to improve the permeability, and the ink is excellent in both dryness and stability over time. It is preferable because it is easy to obtain new ink. Therefore, considering the dryness of handwriting, it is preferable to use the general formula (Chemical Formula 1).

Among the silicone-based surfactants, the weight average molecular weight is preferably 500 to 3000. This is because when the weight average molecular weight of the above-mentioned surfactant exceeds 3000, the molecules of the silicone-based surfactant tend to become too large and the arrangement at the gas-liquid interface tends to be delayed. Therefore, the dryness of the brush stroke may not be sufficient. On the other hand, when the weight average molecular weight is 3000 or less, the molecules of the silicone-based surfactant tend to be relatively small, so that the activator molecules tend to be rapidly arranged at the gas-liquid interface, and the handwriting is dry. Easy to improve. Further, when the weight average molecular weight is less than 500, it is difficult to obtain the desired handwriting drying property. Considering the above effects, the weight average molecular weight is preferably 500 to 3000, more preferably the weight average molecular weight is 500 to 2000, and further considering, the weight average molecular weight is 1000 to 2000. Is preferable. Further, regarding x and y of the general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3), considering that the weight average molecular weight is not increased and the handwriting drying property is more easily improved. The range of x, y = 0 to 1 is preferable.

Regarding the solubility parameter (hereinafter referred to as SP value) of the silicone-based surfactant, the SP value is preferably 8 to 13 in consideration of handwriting drying property, and further considered, the SP value is 9 to 12. It is preferable that the SP value is 10 to 11, and the SP value is particularly preferable. The SP value of water, which is the main component of the solvent, is 23.4, and if the SP value of the silicone-based surfactant is too close, it stabilizes in the dissolved state, so that the activator molecules are quickly arranged at the gas-liquid interface. It tends to be difficult to achieve. When the SP value is in the above range, the activator molecules can be easily arranged at the gas-liquid interface, and stability in the ink can be obtained, which is preferable.

Specifically, the silicone-based surfactants are the Silface series (manufactured by Nisshin Chemical Industry Co., Ltd.), the BYK series (manufactured by Big Chemie Co., Ltd.), the Silkof Spread series, and the Coatosil series (all of which are momentary performances). Materials Co., Ltd.) and the like. These may be used alone or in mixture of 2 or more types.

Further, the content of the silicone-based surfactant is more preferably 0.01 to 3.0% by mass with respect to the total amount of the ink composition. This is because if the content of the silicone-based surfactant is less than 0.01% by mass, it is difficult to obtain the desired handwriting drying property, and if it exceeds 3.0% by mass, the stability of the ink with time is affected. This is because it is easy. Further, more consideration is given, preferably 0.05 to 2.0% by mass, and particularly preferably 0.1 to 1.5% by mass.

<Colorant>
The colorant used in the present invention is not particularly limited, but pigments, dyes and the like used in the ink composition for water-based ballpoint pens can be used.

Examples of pigments include inorganic, organic, and processed pigments. Specifically, carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, quinophthalone, and slene. Examples thereof include based, triphenylmethane, perinone, perylene, dioxazine, microcapsules, aluminum pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, complementary color pigments and the like. As the dye, direct dyes, acid dyes, basic dyes, gold-containing dyes, various salt-forming type dyes and the like can be adopted. These pigments and dyes may be used alone or in combination of two or more.
While the dye is in a dissolved state in the ink, the pigment is dispersed in the ink in an insoluble state. Therefore, the pigment is more likely to have inferior permeability to the paper surface than the dye, and the handwriting drying property is improved. Hard to improve. However, in the present invention, it is preferable to use a silicone-based surfactant such as the general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3) because it is preferably used even when a pigment is used. Further, it is preferable to use a pigment in consideration of excellent water resistance and light resistance, good color development, and an effect of suppressing ink leakage due to insolubility of the pigment.

Among these colorants, it is preferable to use a pigment having a primary average particle size of 1 to 100 nm. By setting the above range, when the silicone-based surfactant permeates the paper surface, the pigment together with the silicone-based surfactant can easily permeate into the paper surface without being caught in the fibers of the paper surface. This is because it is easy to improve the dryness of the stroke after writing, and it is easy to obtain a synergistic effect with the silicone-based surfactant, which is effective. Considering more, it is preferable to use a pigment having a primary average particle size of 5 to 40 nm, and more considering it, it is preferable to use a pigment having a primary average particle size of 10 to 30 nm, and it is most preferable to use a pigment having a primary average particle size of 10 to 20 nm. preferable.
The average particle size of the pigment is the particle size when the cumulative volume of the particle size distribution measured by the laser diffraction method using a laser diffraction type particle size distribution measuring machine (trade name "Microtrac HRA9320-X100", Nikkiso Co., Ltd.) is 50%. It can be measured by (D50).

In particular, when carbon black is used, it is preferable to use a carbon black 10% by mass aqueous dispersion having a pH value in the range of 5 to 10. This is because when the pH value is less than 5, many acidic groups are present on the surface of the carbon black, so that the carbon black exhibits hydrophilicity and dispersibility in water becomes high. In order to improve the handwriting drying property, it is preferable to obtain a certain level of fixability on the paper surface after writing, thereby improving the scratch resistance and easily improving the handwriting drying property. If it is less than 5, if the hydrophilicity is too high, it tends to take time to obtain the fixability due to the influence of the moisture of the ink transferred on the paper surface, and the handwriting drying property tends to be inferior. On the other hand, when the pH value is 5 or more, fixing to the paper surface can be obtained in a relatively short time due to a synergistic effect with the surfactant, the abrasion resistance is improved, and the handwriting drying property is easily improved. The value is preferably 5 or more. Further, when the pH value exceeds 10, the strong basic group on the surface of carbon black may affect the balls of the metal material or hinder the orientation of the surfactant, and the writing quality tends to be inferior. The pH value is preferably 10 or more because it is easy to wear. Therefore, when the pH value of the carbon black 10% by mass aqueous dispersion is in the range of 5 to 10, the fixability is improved, the handwriting drying property is improved, and the effect of the surfactant is not hindered, and the balls are formed. It is preferable because the receiving seat is not worn and the writing quality is smooth. For further consideration, it is preferable that the pH value of the carbon black 10% by mass aqueous dispersion is in the range of 6 to 10.
As the pH value of the aqueous dispersion of 10% by mass of carbon black, the value obtained by measuring the aqueous dispersion of carbon black when the concentration of carbon black is 10% by mass is used.
The 10% by mass of carbon black aqueous dispersion can be adjusted by dispersing the carbon black in water while stirring or by diluting a commercially available carbon black aqueous dispersion.

In the present invention, when a pigment is used as the colorant, an aqueous dispersion pigment product or the like finely and stably dispersed in an aqueous medium using a pigment dispersant may be used in advance. Examples of the pigment dispersant include water-soluble resins, nonionic surfactants, anionic surfactants, and cationic surfactants.

The content of the colorant is preferably 1.0 to 20.0% by mass with respect to the total amount of the ink composition. If it is less than 1.0% by mass, it tends to be difficult to obtain a handwriting with good color development, and if it exceeds 20.0% by mass, the solubility in ink and the stability over time due to aggregation tend to be affected. This is because, considering the tendency, 3.0 to 10.0% by mass is most preferable.

<Water>
The water is not particularly limited, and for example, ion-exchanged water, ultrafiltered water, distilled water, or the like can be used.

<Organic resin particles>
Further, it is preferable to use organic resin particles in the ink composition of the present invention.
The ink composition of the present invention is obtained by selecting one or more of the silicone-based surfactants represented by the structural formulas such as (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3). Since the wettability to the paper surface is improved, the permeability to the paper is improved, and good handwriting drying property and good writing quality can be obtained. On the other hand, the wettability with the ball or the ballpoint pen tip is increased, and there is a possibility that the ink leaks from the gap between the ball and the inner wall of the tip of the ballpoint pen tip. In particular, when the ink composition of the present invention is used for a ballpoint pen such as a haunting ballpoint pen whose pen tip is exposed and can be in a cap-off state at all times, there is a very high possibility that ink leakage may occur. It is conceivable to prevent this problem of ink leakage by increasing the ink viscosity of the ink composition, but in this case, the time until the obtained handwriting is completely dried increases, and the handwriting drying performance is inferior. Furthermore, the amount of ink consumed decreases, and the writing quality tends to be inferior.
However, the organic resin particles can effectively suppress the problem of ink leakage from the pen tip as described above, and at the same time, excellent handwriting drying property and good handwriting can be obtained. Therefore, in the present invention, it is particularly preferable to use organic resin particles. The organic resin particles can cause a physical obstacle in the gap between the ball and the inner wall of the tip of the ballpoint pen tip to suppress ink leakage, but the organic resin particles are harder than the inorganic particles. The ink leakage suppression effect is high because the particles are partially deformed and adhere to each other to form a weak agglomerated structure.
Further, the organic resin particles not only suppress ink leakage as described above, but also can enter between the ball and the ball seat to make it difficult to make direct contact with the ball, so that the rotational resistance of the ball is relaxed and the ball is formed. It is possible to suppress the wear of the seat and improve the writing quality.

Regarding the organic resin particles, olefin resin particles such as polyethylene resin and polypropylene resin, and organic resin particles having hydrogen-bonding functional groups such as sulfonic acid group, phosphoric acid group, amino group, imino group, hydroxyl group and carboxyl group are used. It is preferable to use it.
Recently, in the case of a ballpoint pen in a cap-off state such as a haunting ballpoint pen, when the ballpoint pen tip is returned to the display case with the tip protruding, the ballpoint pen with test writing etc. is returned to the display case. As you repeat this process, you may find that many ballpoint pens are piled up on top of the first ballpoint pen you put back. As a result, due to the weight of the plurality of ballpoint pens stacked, the ball at the tip of the ballpoint pen tip moves in the vertical direction, and a gap may be widened between the ball and the inner wall of the tip of the tip to cause ink leakage. Assuming that the occurrence of ink leakage as described above is suppressed, it is preferable to use olefin resin particles having a remarkably high ink leakage suppressing effect.

This is optimized so that olefin-based resin particles, which are non-polar, tend to aggregate in water, suppress ink leakage, and do not cause problems such as insufficient ink amount. It is presumed that the effect of suppressing ink leakage can be obtained because the aggregated structure is easily formed. Furthermore, since the olefin-based resin particles have a high melting temperature, they are likely to exist stably even in a high-temperature environment, and are easily deformed and difficult to be modified in a high-pressure environment. Since it is stable even if it is sandwiched between the ball and the ball seat, a cushioning effect can be obtained, the writing quality can be improved, and the wear of the ball seat can be suppressed, so that it can be used more preferably. By using it in combination with the silicone-based surfactant, it is possible to further improve the lubricity.

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 suppressing ink leakage and improving writing quality, and specifically, low-density polyethylene, high-density polyethylene, low-molecular-weight polyethylene, modified polyethylene, and modified high-density polyethylene. And so on. 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 each other. Low-density polyethylene is preferable because it is easy to make, gaps between particles are hard to occur, and ink is hard to leak. Furthermore, since low-density polyethylene is soft, it is easy to obtain a cushioning effect between the balls and the ball seat, and the writing taste is good. It can be preferably used because it improves the above and suppresses wear of the ball seat. The olefin-based resin particles may contain a material other than polyolefin, if necessary.

Based on the above, the ink composition of the present invention comprising one or more selected from the structural formulas of the general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3) as the silicone-based surfactant is used. By including the organic resin particles, it is possible to effectively prevent ink leakage from the pen tip while maintaining excellent handwriting drying property, and it is possible to further improve the writing quality.

As the shape of the organic resin particles, spherical or irregular shapes can be used, but spherical resin particles are preferable in consideration of reducing frictional resistance. The spherical resin particles referred to here are not limited to true spheres, and may be substantially spherical resin particles, substantially elliptical spherical resin particles, or the like.

When the olefin-based resin particles are used, it is preferable to use an olefin-based resin particle dispersion dispersed in water or the like in advance, but the pH value of the olefin-based resin particle dispersion is preferably 7 to 11. This is because the dispersion stability of the olefin-based resin particle dispersion and the stability to ink components such as colorants and surfactants are likely to be improved. With more consideration, pH values 7 to 10 are more preferable.

Further, the content of the organic resin particles is more preferably 0.01 to 10.0% by mass with respect to the total amount of the ink composition. This is because if the content of the organic resin particles is less than 0.01% by mass, it is difficult to suppress ink leakage, and if it exceeds 10.0% by mass, the aggregated structure tends to be strong, and the writing quality and dry-up performance are improved. This is because it is easily affected. Further, more considering it, 0.05 to 5.0% by mass is preferable, 0.1 to 3.0% by mass is particularly preferable, and 0.5 to 2.0% by mass is most preferable.

Further, it is preferable to use a water-soluble solvent in consideration of dissolution stability of water, prevention of water evaporation and drying, and the like. Polyhydric alcohol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, glycerin, methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol, allyl alcohol, 3-methyl -1-Butin-3-ol, alcoholic solvents such as ethylene glycol monomethyl ether acetate and other higher alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 3-methoxybutanol, 3-methoxy-3-methylbutanol And the like, such as glycol ether solvent. These may be used alone or in mixture of 2 or more types.

Further, as the water-soluble solvent, it is preferable to use a water-soluble solvent having an SP value different from the SP value of the silicone-based surfactant. This is because if the SP value of the water-soluble solvent and the SP value of the silicone-based surfactant are too close, they are stabilized in the dissolved state, so that it tends to be difficult to quickly arrange the activator molecules on the gas-liquid interface. It is in. Therefore, if a water-soluble solvent having an SP value different from the SP value of the silicone-based surfactant is used, the activator molecules can be easily arranged at the gas-liquid interface, and stability in the ink can be obtained. ,preferable. Therefore, considering the stability in the ink, the difference between the SP value of the silicone-based surfactant and the SP value of the water-soluble solvent is preferably 1 or more, and more considering it, 3 or more. It is preferable to have.

The content of the water-soluble solvent is preferably 0.1 to 25.0% by mass with respect to the total amount of the ink composition in consideration of solubility, ink leakage, bleeding, etc., and 7 in consideration of ink leakage. .0 to 20.0 mass or less is preferable.

Further, by using a lubricant, the rotation of the ball becomes smooth and the lubricity is improved. As the lubricant, it is preferable to use a phosphoric acid ester-based surfactant and a fatty acid in order to suppress wear of the ball seat and improve the writing quality. In particular, it is preferable to use a phosphoric acid ester-based surfactant having a phosphoric acid group. This is because the phosphoric acid group adsorbs the metal to further improve the lubricity, and it is easy to suppress the wear of the ball seat and improve the writing quality. Examples of the type of phosphoric acid ester-based surfactant include styrenated phenol-based, nonylphenol-based, lauryl alcohol-based, tridecyl alcohol-based, octylphenol-based, and hexanol-based. Among these, it is preferable to use a phosphate ester-based surfactant that does not have a phenyl skeleton because the lubricity is likely to be affected by steric hindrance if it has a phenyl skeleton. Considering more lubricity, lauryl alcohol-based and tridecyl alcohol-based phosphate ester-based surfactants are preferable, and these may be used alone or in combination of two or more. In particular, by using the silicone-based surfactant and the organic resin particles in combination, it is possible to further improve the lubricity and improve the writing quality and the abrasion suppression of the ball seat, which is more effective. ..

Specific examples of the phosphate ester-based surfactant include Plysurf A212C (tridecyl alcohol type), A208B (lauryl alcohol type), and Plysurf series (Daiichi Kogyo Seiyaku Co., Ltd.). Examples thereof include A213B (lauryl alcohol type), A208F (short chain alcohol type), A215C (tridecyl alcohol type), and A219B (lauryl alcohol type). Specific examples of fatty acids include OS soap, NS soap, FR-14, FR-25 (Kao Corporation) and the like. These phosphoric acid ester-based surfactants and fatty acid salts may be used alone or in combination of two or more.

Further, in the ink composition of the present invention, it is preferable to use dextrin in order to suppress ink leakage.
This is because by using dextrin, a film is formed when the ink on the pen tip dries, so ink leakage from the gap between the ball and the inner wall of the tip tip can be suppressed, or the pen tip can be dried up. This is because it is easy to obtain the effect of improving the performance. In particular, in the present invention, the combined use of the organic resin particles and dextrin is more effective in suppressing ink leakage.

The weight average molecular weight of the dextrin is more preferably 5000 to 120,000. When the weight average molecular weight of dextrin exceeds 120,000, the film formed on the pen tip is hard, and the handwriting tends to be easily blurred when writing out during dry-up. On the other hand, when the weight average molecular weight is less than 5,000, the moisture absorption property is reduced. This is because the film tends to be high and the film formed on the pen tip tends to be soft, and it tends to be difficult to sufficiently obtain the effect of suppressing ink leakage. Further, when the weight average molecular weight is smaller than 20000, the film tends to be thin, so that the weight average molecular weight is most preferably 20000 to 120,000.

The content of the dextrin in the ink composition is preferably 0.1 to 5% by mass based on the total mass of the ink composition. If it is less than 0.1% by mass, the effect of suppressing ink leakage and improving the dry-up performance of the pen tip tends not to be sufficiently obtained, and if it exceeds 5% by mass, it tends to be difficult to dissolve in the ink. Because. Considering the solubility in ink, it is preferably 0.1 to 3% by mass, and more considering the suppression of ink leakage and the improvement of dry-up performance, it is most preferably 1 to 3% by mass. preferable.

The water-based ink composition of the present invention preferably contains an ink viscosity modifier. As the ink viscosity modifier, it is preferable to use a shear thinning agent.
Examples of the shear thinning agent include crosslinked acrylic acid polymers, polysaccharides such as xanthan gum, welan gum, succinoglycan, guar gum, locust bean gum, λ-carrageenan, cellulose derivatives, and dietangum, and association-type augmentation. A viscous agent can be mentioned. Examples of the associative thickener include associative thickeners such as polyester-based, polyether-based, urethane-modified polyether-based, and polysaccharide-based thickeners depending on the associative hydrophobic group, and alkaline swelling associative thickeners. Examples thereof include nonionic thickeners, and among these, polysaccharides and association thickeners are preferably used in consideration of the stability over time of the ink. These shear thinning agents may be used alone or in combination of two or more.

Further, the association type thickener is preferable because it has an effect of easily improving the handwriting drying property and the pigment dispersibility. The associated thickener has a hydrophilic group as a skeleton and has a hydrophobic group at a side chain or a terminal, and when a pigment is used, the hydrophobic group of the associated thickener becomes a pigment. By adsorption, a mutual structure between the pigment and the associated thickener is formed in the ink. At the time of writing, the pigment and the associative thickener that formed the mutual structure by the silicone-based surfactant quickly permeate the paper surface, and the mutual structure is three-dimensionally partially entangled with the paper fiber on the paper surface. It is estimated that it will settle in. Since each component in the ink acts as a penetrant and a fixing agent to improve the abrasion resistance, the handwriting drying property is likely to be improved. Further, it is preferable to use an associative thickener because the hydrophobic group is adsorbed on the pigment and functions as a dispersant to easily improve the pigment dispersibility. Considering that the handwriting drying property and the pigment dispersibility are further improved, it is preferable to use an alkaline swelling association type thickener.

Further, when the pigment and the organic resin particles are used in the associative thickener, the hydrophobic group of the associative thickener is adsorbed on the pigment and the organic resin particles to form a dense three-dimensional structure. Therefore, even when the ink viscosity is low, the effect of suppressing ink leakage can be easily obtained. Further, in consideration of the above-mentioned improvement in the effect, it is preferable to use an alkaline swelling association type thickener among the association type thickeners. This is because the alkali swelling association type thickener has a high ink viscosity development efficiency among the association type thickeners, and when the pigment and the organic resin particles are used, the adsorptivity to the pigment and the organic resin particles is higher. This is because it is easy to form a crosslinked structure and a dense three-dimensional structure is formed, so that it is easy to improve ink leakage suppression.

The alkali swelling association type thickener has a polymerizable property of a monomer or a copolymer containing various polymerizable monomers having a carboxyl group such as acrylic acid, methacrylic acid, and maleic acid as a mechanism for exhibiting alkali swelling property. Examples of resins include resins, which are preferable because they have stable swelling properties for a long period of time because they can be expected to have effects of suppressing ink leakage and further improving pigment dispersibility to easily improve ink stability over time. Of these, those composed of three types of monomers, vinyl acetate, methyl methacrylate, and methacrylic acid, are particularly preferable.

The content of the ink viscosity modifier in the ink composition is more preferably 0.01 to 5% by mass based on the total mass of the ink composition. This is because if the content of the shear thinning agent is less than 0.01% by mass, the ink thickening effect is not sufficient and it is difficult to suppress ink leakage, and if it exceeds 5% by mass, the ink viscosity becomes high. This is because it is easy to suppress wear of the ball seat, ink followability at the time of writing, writing taste, and dry-up resistance are easily affected. Further, more consideration is given, preferably 0.1 to 2% by mass, and most preferably 0.1 to 1% by mass.

Further, an additive can be contained if desired, specifically, a pH adjuster, a fluorosurfactant, a surfactant having an acetylene bond, and a succinic acid in order to improve the stability of the colorant over time. Wetting agents such as surfactants, fixing agents such as acrylic resin emulsions, urethane resin emulsions and styrene-butadiene resin emulsions, antibacterial agents such as 1,2-benzoisothiazolin-3-one, and moisturizers such as urea and sorbit. Agents, rust preventives such as benzotriazole, chelating agents such as ethylenediamine tetraacetic acid and the like can be added. These can be used alone or in combination of two or more.

The pH of the aqueous ink composition of the present invention is preferably 7 to 11. This is because when the pH is within the above numerical range, each component in the ink composition can be stably present, which is preferable, and corrosion of the ballpoint pen tip can be prevented. 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).

<Aqueous ballpoint pen>
The ink composition of the present invention can be suitably used for a water-based ballpoint pen having a ballpoint pen tip that rotatably holds a ball at the tip of an ink containing cylinder.

In the present invention, it is conceivable to increase the ink consumption of the water-based ballpoint pen in consideration of obtaining a smooth writing taste and a handwriting with good color development. However, as the ink consumption increases, the drying performance of the obtained handwriting deteriorates, and it becomes difficult to obtain a good handwriting.
Therefore, as a result of further diligent studies, the present inventor has determined the relationship between the specifications of the ballpoint pen tip and the ink consumption amount when the ink consumption amount per 100 m of the ballpoint pen is A (mg) and the ball diameter is B (mm). , 110 ≦ A / B ≦ 600, it was found that the handwriting was excellent in dryness, the handwriting with good color development was obtained, and the writing taste was smoother. Further, considering that the excess ink on the paper surface is suppressed and the handwriting drying property is improved by suppressing the bottom, it is preferable to set 120 ≦ A / B ≦ 500, and further, the above effect can be further enhanced. Considering this, it is preferable that 150 ≦ A / B ≦ 450.
The amount of ink consumed per 100 m of a ballpoint pen is the amount of ink used for writing a 100 m writing line, and is subject to the conditions of 25 ° C., writing paper JIS P3201, writing angle 65 °, and writing load 100 g. Then, a spiral writing test was conducted for 25 minutes at a writing speed of 4 m / min using five test samples, and the average value of the amount of ink used (decrease) used at that time was calculated as the ink per 100 m. Defined as consumption.
The ball diameter is not particularly limited, but a ball having a diameter of about 0.1 to 2.0 mm is used.

Therefore, the ink composition of the present invention containing the silicone-based surfactant has 110 ≦ A / B ≦ when the ink consumption per 100 m is A (mg) and the ball diameter is B (mm). In the water-based ballpoint pen having a relationship of 600, it is possible to obtain a smooth writing taste at the same time as being excellent in handwriting drying performance.

Further, in the water-based ballpoint pen of the present invention, the arithmetic mean roughness (Ra) of the surface of the ball is preferably 0.1 to 5 nm. When the arithmetic mean roughness (Ra) of the surface of the ball is 0.1 nm or more, the ink is sufficiently applied to the surface of the ball, and a handwriting with good color development can be obtained. When it is 5 nm or less, it is possible to prevent the writing quality from being deteriorated due to the unevenness of the surface of the ball and the rotational resistance between the ball and the ball seat from being increased to be deteriorated.
Further, the ink composition containing the silicone-based surfactant easily adheres to the surface of the ball whose surface arithmetic average roughness (Ra) is within the above numerical range, and is evenly applied to the paper surface. It is possible to transfer an appropriate amount of ink composition to the ink composition. Therefore, while maintaining sufficient color development, it is difficult for more ink composition than necessary to be transferred to the paper surface, so that handwriting drying property is improved.
Further, in consideration of obtaining handwriting dryness and smooth and good writing quality, the arithmetic mean roughness (Ra) of the surface of the ball is preferably 0.5 to 3 nm.
The above arithmetic average roughness (Ra) can be measured with a surface roughness measuring instrument (manufactured by Seiko Epson, model name SPI3800N), and from the measured roughness curve, the reference length is in the direction of the average line. It is the average value obtained by summing the absolute values of the deviations from the average line of the extracted portion to the measurement curve.

Further, the amount of movement (clearance) of the ball of the ballpoint pen tip of the water-based ballpoint pen of the present invention in the vertical axis direction is preferably 20 to 45 μm. This is because if the amount of movement (clearance) is within the above numerical range, an appropriate amount of ink composition is transferred to the paper surface at regular intervals to suppress stickiness, suppress excess ink on the paper surface, and handwriting. It is easy to improve the dryness, and in particular, when the silicone-based surfactant is used, it is easy to improve the handwriting dryness, which is more effective. Further, if the movement amount (clearance) is within the above numerical range, the relationship between the ink consumption amount and the ball diameter when the ink consumption amount per 100 m is A (mg) and the ball diameter is B (mm) is determined. It is easy to set 110 ≦ A / B ≦ 600, it is excellent in handwriting drying property, and it is easy to obtain a good handwriting without rubbing the paper surface or the handwriting and making it dirty. Considering the above effects and writing taste, it is preferably 30 to 45 μm, and further considering it, it is preferably 30 to 40 μm.
The amount of movement (clearance) of the ball in the ballpoint pen tip in the vertical direction indicates the distance that the ball can move in the vertical direction of the ballpoint pen tip body.

<Manufacturing method of ink composition>
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 a propeller stirrer, a homodisper, or a homomixer, or various dispersers such as a bead mill to produce the product.

Next, the present invention will be described with reference to examples.
Example 1
Pigment dispersion (pH value 9 of carbon black, 10% by mass of carbon black aqueous dispersion, primary average particle diameter 17 nm)) 20.0 parts by mass
64.1 parts by mass of water
Polyhydric alcohol (ethylene glycol: SP value 14) 10.0 parts by mass
Silicone-based surfactant (Chemical formula 1) 0.3 parts by mass
Organic resin particles (low density polyethylene dispersion, average particle diameter 6 μm, pH value 9, solid content 40%) 0.5 parts by mass
Dextrin (weight average molecular weight: 100,000) 1.0 part by mass
pH adjuster (triethanolamine) 2.0 parts by mass
Lubricant (phosphate ester-based surfactant) 1.0 part by mass
Rust inhibitor (benzotriazole) 0.5 parts by mass
Shear thinning agent (alkaline swelling association type thickener) 0.6 parts by mass

A base ink was prepared by heating and stirring a pigment dispersion, water, polyhydric alcohol, a silicone-based surfactant, organic resin particles, dextrin, a pH adjuster, a lubricant, and a rust preventive with a magnetic hot stirrer.

Then, while heating the prepared base ink, a shear thinning agent is added and sufficiently mixed and stirred using a homogenizer stirrer until a uniform state is obtained, and the ink composition for an aqueous ballpoint pen according to Example 1 is obtained. Got
The ink viscosity of Example 1 was measured using a DV-II viscometer (CPE-42 rotor) manufactured by Brookfield Co., Ltd. in an environment of 20 ° C. and a shear rate of 1.92 sec ^-1 (rotation speed 0.5 rpm). When the ink viscosity was measured under the conditions, it was 500 mPa · s.
The pH value of Example 1 was measured at 20 ° C. using an IM-40S type pH meter (manufactured by DKK-TOA CORPORATION), and the pH value was 8.8.

Examples 2-18
The ink compositions for water-based ballpoint pens of Examples 2 to 18 were obtained in the same procedure as in Example 1 except that the ink composition was changed as shown in the table. The table shows the ink formulation and evaluation results.

Comparative Examples 1-3
The ink compositions for water-based ballpoint pens of Comparative Examples 1 to 3 were obtained in the same procedure as in Example 1 except that the ink composition was changed as shown in the table. The table shows the ink formulation and evaluation results.

Tests and Evaluations The ink compositions for water-based ballpoint pens prepared in Examples 1 to 18 and Comparative Examples 1 to 3 were rotatably held by a ballpoint pen tip (ball) having a ball diameter of 0.7 mm at the tip of an ink containing cylinder. Pilot Corporation Co., Ltd. filled a refill (1.0 g) filled in an ink containing cylinder (made of polypropylene) having a diameter: 0.7 mm and an arithmetic average roughness (Ra) of the ball surface (1 nm) via a chip holder. It was mounted on a gel ink ballpoint pen (trade name: G-2) manufactured by Japan, and the following tests and evaluations were performed. The amount of movement (clearance) of the ballpoint pen tip in the vertical direction is as shown in the table. For the evaluation of writing taste and handwriting density, JIS P3201 writing paper A was used as the writing test paper, and the evaluation was performed by the following test method.
Further, when a spiral writing test is performed as a water-based ballpoint pen using the ink composition for a water-based ballpoint pen of Example 1, the ink consumption of the ballpoint pen per 100 m is A (mg), and the ball diameter is B (mm). , A = 190 (mg), the ball diameter was B = 0.7 (mm), and A / B = 271.

Handwriting drying performance test After writing on the paper, the handwriting was scraped with tissue paper every elapsed time, and the handwriting drying performance was evaluated according to the following criteria.
Writing is less than 3 seconds and the handwriting is dry ... ◎◎
Writing that has dried in 3 seconds or more and less than 5 seconds ... ◎
Writing that has dried in 5 seconds or more and less than 10 seconds ... ○
Writing in 10 seconds or more and less than 20 seconds, and the handwriting is dry ... △
The handwriting did not dry even after 20 seconds of writing ... ×

Writing taste: A handwritten sensory test was conducted and evaluated.
It was an extremely smooth writing taste ... ◎
It was a smooth writing ... ○
I felt a little heavy writing, but it was at a level where there was no problem in practical use ... △
It was heavy and slippery ... ×

Ink leakage test: A weight of 40 g is attached to the barrel of the water-based ballpoint pen for testing, the ballpoint pen tip is ejected and turned downward, and the ball of the ballpoint pen tip is kept in contact with the bottom of the ballpoint pen display case. The ink was left in an environment of ℃ and 65% RH for one day, and the amount of ink leaked from the tip of the ballpoint pen tip was measured.
Ink leakage amount less than 20 mg ・ ・ ・ ◎
Ink leakage amount of 20 to 50 mg ... ○
Ink leakage amount of 50 mg to 100 mg ... △
Ink leakage amount of 100 mg or more ・ ・ ・ ×

From the results in the table, in Examples 1 to 18, good levels of performance were obtained in all of the handwriting drying performance test, writing taste, and ink leakage test.

From the results in the table, in Comparative Example 1, since none of the silicone-based surfactants of the general formulas (Chemical Formula 1) to (Chemical Formula 3) was used, the level was inferior in the handwriting drying performance test.

In Comparative Examples 2 and 3, since a surfactant other than the silicone-based surfactant was used, the level was inferior in the handwriting drying performance test.

Based on the above, an ink for water-based ballpoint pens containing one or more silicone-based surfactants selected from the general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3) as silicone-based surfactants. The composition can improve the writing quality by improving the dryness of the brush stroke and the lubricity, and it was found that the water-based ballpoint pen using the ink composition is excellent as a water-based ballpoint pen. It was.

Generally, in a ballpoint pen tip of a water-based gel ballpoint pen, in order to suppress ink leakage, a ball rotatably held at the tip of the ballpoint pen tip is held directly by a repulsive member such as a coil spring or via a pressing body at the tip edge of the tip. It is preferable to provide a valve mechanism that presses against the inner wall and gives a gap between the inner wall of the tip edge of the chip and the ball to allow ink to flow out by pressing pressure at the time of writing, and closes even a minute gap at the tip of the tip when not in use.

The present invention can be used as a water-based ballpoint pen, and more specifically, can be widely used as a cap-type, haunting-type, or the like water-based ballpoint pen.

Claims (6)

A water-based ballpoint pen having a ballpoint pen tip at the tip of an ink storage cylinder, and accommodating an ink composition for a water-based ballpoint pen containing water, a colorant, and a silicone-based surfactant in the ink storage cylinder. Then, one or more of the silicone-based surfactants are selected from the following general formulas (Chemical formula 1), (Chemical formula 2), and (Chemical formula 3), and the arithmetic average roughness (Ra) of the ball surface of the water-based ballpoint pen. Is 0.1 to 5 nm, the amount of movement (clearance) of the ball of the ballpoint pen tip in the vertical axis direction is 20 to 45 μm, the ink consumption per 100 m of the water-based ballpoint pen is A (mg), and the ball diameter is set. A water-based ballpoint pen characterized in that the relationship between the amount of ink consumed and the ball diameter when B (mm) is 120 ≦ A / B ≦ 500.
The water-based ballpoint pen according to claim 1, wherein the colorant is carbon black, and the pH value of the carbon black 10% by mass aqueous dispersion is 5 to 10. The water-based ballpoint pen according to claim 1 or 2, wherein the silicone-based surfactant has a weight average molecular weight of 500 to 3000. The water-based ballpoint pen according to any one of claims 1 to 3, wherein the colorant is a pigment. The water-based ballpoint pen according to any one of claims 1 to 4, wherein the ink composition for a water-based ballpoint pen contains organic resin particles. The water-based ballpoint pen according to claim 5, wherein the organic resin particles are an olefin resin.

Commissioner of the Patent Office, Examiner of the Japan Patent Office, Kosuke Yanagimoto

Regarding this amendment ・ Regarding Japanese Patent Application No. 2016-257169, "Claim 7" was deleted because there was a deficiency in "Claim 7" of the amendment submitted on July 8, 2nd year of Reiwa.
The number of claims has changed from 7 to 6.