JP6796958B2 - Aqueous ink composition for writing instruments and writing instruments using it - Google Patents

Description

The present invention relates to a water-based ink composition for a writing instrument and a writing instrument using the same.

The writing instrument has a structure in which a pen tip is attached to the end of a shaft tube via an appropriate ink flow rate adjusting body for adjusting the ink flow rate, and an ink tank for accommodating the water-based ink composition is provided in the shaft cylinder. There is. In this type of writing instrument, in order to write from the horizontal state or the pen tip upward state, when the pen tip is in the downward state, the water-based ink composition contained in the ink tank travels along the inner wall of the ink tank toward the pen tip. Writing becomes possible by flowing down to. (The mobility of this water-based ink composition is referred to as ink reversibility.)
However, many parts of writing instruments, including ink tanks, are often made of resin and are hydrophobic, so if the water-based ink composition lacks wettability, the writing instrument can be turned downward. Due to the resistance due to surface tension, the water-based ink composition does not flow down and stays in its original position. In this state, the water-based ink composition is not supplied to the pen tip, and the handwriting may be faint or, in the worst case, writing may not be possible.

In order to solve the above problems, it is generally considered to reduce the surface tension of the water-based ink composition, but the surface tension plays an important role as a drag against the movement of the water-based ink composition due to gravity, atmospheric pressure, and impact. I'm playing. Therefore, when the surface tension of the water-based ink composition is lowered to improve the ink reversibility in the ink tank, the resistance is insufficient. Therefore, when the pen tip is turned downward, even when not writing, a small amount is obtained. Ink may leak out due to impact or vibration, or ink may overflow due to a change in atmospheric pressure, which may cause a new problem of ink dripping.

Therefore, an aqueous ink composition has been proposed in which an additive such as maltosyl cyclodextrin is added to improve the ink reversibility in the ink tank without lowering the surface tension. (Patent Document 1)
However, when the maltosyl cyclodextrin or the like is added to an aqueous ink composition to such an extent that good ink reversibility can be obtained, the ink viscosity increases, the ink followability decreases, and the solubility in water is low. Therefore, there are problems such as affecting the dry-up resistance of the pen tip.

As described above, in the conventional water-based ink composition, if the surface tension is lowered to improve the wettability to the ink tank made of a resin material in order to improve the ink reversibility in the ink tank, the drag force is insufficient. Ink cannot be retained, and ink drips. On the other hand, if the surface tension is raised to a certain value, the ink reversibility in the ink tank cannot be sufficiently obtained. Therefore, it has been difficult to simultaneously solve the two problems of improving the ink reversibility in the ink tank and suppressing the ink dripping.
Further, in the conventional ink composition which tried to solve the above problem without adjusting the surface tension, when it is housed in a writing instrument and used, problems occur in the writing property and the obtained handwriting, and as a water-based ink composition. I was not fully satisfied with the performance of.
In particular, a writing instrument having a structure in which a pen tip is attached to the end of a shaft tube via an appropriate ink flow rate adjusting body for adjusting the ink flow rate and an ink tank for accommodating the water-based ink composition is provided in the shaft tube. In a water-based ink composition for writing instruments having a high viscosity index n and a water-based ink composition for writing instruments having a low viscosity, which are preferably used, it is difficult to solve the above problems at the same time, which has been a big problem.

Japanese Unexamined Patent Publication No. 5-140498

The present invention uses a water-based ink composition for writing instruments, which has excellent ink reversibility in an ink tank, sufficiently suppresses the ink dripping phenomenon, and can obtain good writing performance and good handwriting, and a water-based ink composition for writing instruments. It provides the writing instruments that were used.

The water-based ink composition for writing instruments according to the present invention comprises water, a colorant, and a polyether amine having an HLB value of 10 to 20, and the surface tension of the water-based ink composition for writing instruments at 20 ° C. is high. A water-based ink composition for writing instruments, which is characterized by having a temperature of 35 to 55 mN / m.

Further, the writing instrument according to the present invention is characterized in that it contains the water-based ink composition for writing instruments.

According to the present invention, for a writing instrument that is excellent in ink reversibility in an ink tank, can sufficiently suppress the ink dripping phenomenon, and can obtain good writing performance and good handwriting. A water-based ink composition and a writing instrument using the same can be provided.

In the present specification, "parts", "%", "ratio" and the like indicating the composition are based on mass unless otherwise specified.

<Aqueous ink composition for writing instruments>
The water-based ink composition for writing instruments according to the present invention (hereinafter, sometimes referred to as a water-based ink composition) comprises water, a colorant, and a polyether amine having an HLB value of 10 to 20. The surface tension of the water-based ink composition for writing instruments at 20 ° C. is 35 to 55 mN / m. Hereinafter, the physical properties and each component constituting the water-based ink composition according to the present invention will be described.

The surface tension of the water-based ink composition of the present invention at 20 ° C. is 35 to 55 mN / m. The water-based ink composition of the present invention is designed so that it can flow out into the ink flow rate adjusting body of a writing instrument by a capillary phenomenon. A writing instrument containing a water-based ink composition may move ink when an external force such as kinetic energy due to gravity, atmospheric pressure, impact, or the like is applied. When the surface tension of the water-based ink composition is 35 mN / m or more, it is possible to have a sufficient drag against the external force, so that it is possible to suppress an ink dripping phenomenon such as unintended ink ejection. Further, when the surface tension of the water-based ink composition is 55 mN / m or less, the function of the capillary phenomenon can be sufficiently exerted, so that the ink ejection from the pen tip is stable, and good writing performance and good handwriting are performed. Can be obtained.
Further, the surface tension of the water-based ink composition is preferably 40 to 50 mN / m in consideration of the suppression of the ink dripping phenomenon and the ejection property of the ink.
The surface tension is measured by the vertical plate method using a surface tension measuring instrument manufactured by Kyowa Interface Science Co., Ltd. and a platinum plate in an environment of 20 ° C.

The water-based ink composition according to the present invention preferably has an ink viscosity of 1 to 3 mPa · s measured at a rotation speed of 60 rpm and 20 ° C. using a B-type rotational viscometer. When the viscosity of the water-based ink composition is within the above numerical range, when it is housed in a writing instrument and used, the ink ejection property from the pen tip and the writing property can be improved, and the ink reversibility in the ink tank can be improved. Can be improved. The ink composition of the present invention can be suitably used as an ink flow rate adjusting body for a writing instrument in which a comb-shaped ink holding member is arranged, but in this case, further considering the ink ejection property, 1 to 2 mPa. It is more preferably s. The viscosity can be measured using a B-type rotational viscometer (model: BLII, rotor: BL adapter, manufactured by Toki Sangyo Co., Ltd.).

The viscosity index n of the aqueous ink composition according to the present invention at 20 ° C. is preferably 0.9 to 1.2. Here, the viscosity index n refers to n in the viscosity formula represented by S = αD ⁿ . S is the shear stress (dyn / cm ² = 0.1 Pa), D is the shear rate (s ^-1 ), and α is the viscosity coefficient. The viscosity index n can be calculated by measuring the ink viscosity using a B-type rotational viscometer (model: BLII, rotor: BL adapter, manufactured by Toki Sangyo Co., Ltd.). The viscosity index n of the water-based ink composition is more preferably 0.95 to 1.15, and even more preferably 1.00 to 1.15. When the viscosity index n of the water-based ink composition is within the above numerical range, it is possible to improve the ink ejection property and the writing property from the pen tip when used for a writing instrument, and also improve the ink reversibility in the ink tank. Can be made to.

The pH of the aqueous ink composition of the present invention is preferably 6.0 to 10.0, more preferably 7.0 to 9.0. When the pH of the aqueous ink composition is within the above numerical range, each component in the ink composition can be stably present, which is preferable, and in particular, a poly having an HLB value of 10 to 20 which is an essential component of the present invention. It is preferable because the ether amine can be stably present and the effect of the polyether amine can be sufficiently obtained. This is because when the pH is 6.0 or more, it is possible to prevent the ethylene oxide moiety in the polyether amine from being hydrolyzed by the acid catalytic effect and the effect of the polyether amine from being lost. Further, when the pH of the water-based ink composition is within the above numerical range, it is possible to prevent corrosion of a metal portion of a writing instrument such as a pen tip that the water-based ink composition comes into contact with. 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).

<Polyether amine>
The water-based ink composition of the present invention comprises a polyether amine having an HLB value of 10 to 20. The polyether amine having an HLB value of 10 to 20 can adjust the surface tension of the aqueous ink composition within an appropriate range, and can appropriately maintain the wettability with respect to the ink tank and the ink flow rate adjusting body.
Since the polyether amine can maintain an appropriate wettability to the ink tank, the water-based ink composition can be used even when the writing instrument is placed horizontally or the pen tip is upward, and the pen tip is downward for writing. It does not stay in its original position in the ink tank, but can flow smoothly toward the pen tip. Therefore, the polyether amine can improve the ink reversibility in the ink tank of the water-based ink composition.
Further, the polyether amine can appropriately maintain not only the wettability to the ink tank but also to the ink flow rate adjusting body. Therefore, the function of the ink flow rate adjusting body can be sufficiently obtained, the ink ejection property from the pen tip can be maintained well, and as will be described later, the comb-shaped ink holding member can be used. Since excess ink can flow in smoothly, it is possible to suppress the ink dripping phenomenon.
Further, since the polyether amine can be adjusted to an appropriate range without extremely lowering the surface tension of the water-based ink composition, when the water-based ink composition of the present invention is housed in a writing instrument and written. It is possible to obtain a good handwriting without blurring or strike-through of the handwriting due to high penetration into the paper surface.

It is essential that the HLB value of polyetheramine, which is a constituent of the present invention, is 10 to 20. This is because when the HLB value of polyetheramine is 10 or more, the effect of polyetheramine can be sufficiently obtained without remaining undissolved in water as a solvent. Furthermore, it is more preferable to select a polyether amine having an HLB value of 15 to 20. This is because the polyether amine having an HLB value of 15 to 20 has particularly good solubility in water, so that the effect of the polyether amine can be obtained more effectively, and the ink reversibility in the ink tank can be obtained. In addition to being able to improve the dry-up resistance of the pen tip, it is possible to improve the writing performance such as good writing performance.

Based on the above, in the present invention, the water-based ink composition for writing instruments containing the polyether amine and having a surface tension at 20 ° C. of 35 to 55 mN / m is provided, whereby the ink reversibility in the ink tank is excellent. In addition, the ink dripping can be sufficiently suppressed, and good writeability and good handwriting can be obtained.

In the present invention, polyetheramine is the main additive for adjusting surface tension. Therefore, among the polyether amines, it is preferable to select one having a surface tension of 35 to 55 mN / m in an environment of 20 ° C. when made into a 1% aqueous solution. This is because when the water-based ink composition contains polyether amine in which the surface tension of the 1% aqueous solution is within the above numerical range, the water-based ink composition has kinetic energy due to gravity, atmospheric pressure, impact, etc. This is because it is possible to obtain a surface tension that can act as an appropriate drag against an external force, and it is possible to effectively suppress the dripping of ink. Considering further suppression of ink dripping phenomenon and improvement of ink ejection property and writing property when used for writing instruments, the surface tension of 1% aqueous solution is 40 to 50 mN / m in an environment of 20 ° C. It is more preferable to select the indicated polyether amine.

Further, the polyether amine can effectively improve the wettability to a resin material such as an ink tank, as compared with a surfactant which brings about the same surface tension when added. The reason for this is presumed to be as follows.
Polyetheramine contains a nitrogen element in its molecule, and this nitrogen element moiety easily binds to hydrogen ions in water, and the complex becomes weakly positively charged. On the other hand, many resin materials are negatively charged, and charge neutralization occurs between the polyether amine and the resin material. Therefore, the aqueous ink composition containing the polyether amine can specifically obtain good wettability with respect to the resin material.
With general surfactants, it is possible to adjust the surface tension of the water-based ink composition to an appropriate range, but the wettability to the resin material is insufficient, and in the case of a resin ink tank, the ink Inversion is seen to be inferior. However, since the water-based ink composition containing the polyether amine can maintain the surface tension of the water-based ink composition within an appropriate range and also improve the wettability with respect to the resin material, the ink can be used. It is possible to improve the ink reversibility in the resin ink tank while preventing the dripping phenomenon.

The average number of moles of ethylene oxide added (the number of EOs) of the polyether amine is preferably 10 to 35, and preferably 13 to 30. When the average number of moles of ethylene oxide added (number of EOs) of the polyether amine is within the above numerical range, the solubility in water is high, so that the effect of the polyether amine can be stably obtained.
Further, in the study process of the present invention, it was confirmed that ethylene oxide in the polyether amine contributes to the bubble stability (foaming property) of the aqueous solution. When the average number of moles of ethylene oxide added (number of EOs) of the polyether amine is within the above numerical range, the bubbles generated in the aqueous ink composition disappear quickly. Therefore, the water-based ink composition can flow smoothly without being hindered by the generated bubbles, and the ink reversibility in the ink tank can be improved. In addition, since the ink ejection property from the pen tip can be improved without being hindered by air bubbles, good writing property and its handwriting can be obtained when used in a writing instrument. In particular, when the ink viscosity of the water-based ink composition of the present invention is measured with a BL adapter, a rotation speed of 60 rpm, and 20 ° C. using a B-type rotational viscometer and is 1 to 3 mPa · s, the ink fluidity is good. Therefore, it is likely to move frequently in the ink tank and bubbles are likely to be generated. Since these generated bubbles cause problems such as ink reversibility in the ink tank, ink ejection property from the pen tip, and confirmation of the remaining amount of ink, it is desirable that the bubbles disappear quickly. Therefore, if the polyether amine having an average number of moles of ethylene oxide added (EO number) within the above numerical range is contained, the rate of disappearance of bubbles can be improved and the above-mentioned problems can be solved, which is particularly effective.

The relationship between ethylene oxide in polyether amine and defoaming property is estimated as follows. Polyetheramine has a structure in which ethylene oxide exists diagonally around the nitrogen atom. Bubbles are stabilized by the coordination of a surfactant at the gas-liquid interface, but due to the V-shaped or Y-shaped structure in which ethylene oxide is present at an angle, the ethylene oxide sites become steric hindrances and normal straight lines. Unlike the state-like surfactant, a sufficient amount cannot be coordinated with respect to the gas-liquid interface on the bubble surface. Therefore, it is considered that the polyether amine causes less bubbles to be generated, and even if they are generated, the bubbles disappear in a good state.
As described above, the property of reducing the generation of bubbles and, even if they are generated, brings about a good state of bubble disappearance depends on the steric hindrance of ethylene oxide. Therefore, it is considered that those having a certain amount of average ethylene oxide addition moles (EO number) of polyether amine are excellent in foam breaking property.

Further, in consideration of improving the ink reversibility in the ink tank and suppressing the ink dripping phenomenon, the cloud point indicated by the 1% aqueous solution of the polyether amine is preferably 50 ° C. or higher. This is because when the cloud point of the polyether amine is 50 ° C. or higher, the solubility in water is stable, so that separation from water does not occur, and the effect of the polyether amine can be sufficiently obtained. Because.

Examples of the polyether amine include polyoxyethylene-stearylamine, polyoxyethylene (20) alkyl (C14-C18) amine, polyoxyethylene-beef alkylamine, polyoxyethylene alkylamine ether, polyoxyethylene laurylamine, and poly. Oxyethylene-alkyl (palm) amine and the like can be mentioned, but moreover, the ink reversibility in the ink tank is improved, the ink dripping phenomenon is suppressed, the writing property when used in a writing tool, and the resulting writing stroke. In consideration of, polyoxyethylene (20) alkyl (C14-C18) amine, polyoxyethylene-alkyl (palm) amine, polyoxyethylene-stearyl amine, and polyoxyethylene-beef alkyl amine are preferable.

The content of the polyether amine in the water-based ink composition is preferably 0.1 to 2.0% by mass, preferably 0.5 to 1.0% by mass, based on the total mass of the water-based ink composition. It is more preferable to have. When the content of the polyether amine is within the above numerical range, it is possible to maintain an appropriate wettability between the ink tank and the ink flow rate regulator without extremely lowering the surface tension of the ink composition. It is possible to improve the ink reversibility in the ink tank and suppress the ink dripping phenomenon.

The water-based ink composition of the present invention can be particularly preferably used as an ink flow rate regulator for a writing instrument on which a comb-shaped ink holding member is arranged.
A writing instrument provided with the ink flow rate adjusting body as described above basically discharges ink by utilizing the capillary phenomenon. When the internal pressure of the ink tank rises, excess ink may be blown out from the pen tip, and the ink may drop out. However, when the comb-shaped ink holding member is arranged, this excess ink is taken into the comb-shaped structure and the ink dripping can be suppressed.
However, in order to effectively use this comb-shaped ink holding member, the water-based ink composition used needs to have a certain degree of wettability with respect to the ink holding member. If the surface tension of the ink composition is simply lowered, the drag force of the ink due to the surface tension becomes insufficient against external forces other than internal pressure changes such as gravity and kinetic energy, and the ink may be held in the ink holding member. become unable. On the contrary, when the surface tension of the ink is extremely high, the ink does not flow smoothly mainly into the ink passage, and the ink ejection property from the pen tip deteriorates.
Since the water-based ink composition of the present invention contains the polyether amine, it not only adjusts the surface tension of the water-based ink composition to an appropriate range, but also an ink flow rate regulator (comb-shaped ink holding member). It becomes possible to maintain an appropriate wettability to the ink. Therefore, the function of the comb-shaped ink holding member can be effectively used, and the ink composition of the present invention can be applied to a writing instrument in which the comb-shaped ink holding member is arranged as the ink flow rate adjusting body as described above. A material can be preferably used, the ink dripping phenomenon can be sufficiently suppressed, and good writeability and handwriting can be obtained.

Further, as described above, the water-based ink composition of the present invention tends to quickly eliminate the generated bubbles, and therefore can be suitably used for a writing instrument in which a comb-shaped ink holding member is arranged. This is because by using the water-based ink composition for writing instruments of the present invention, air bubbles generated in the water-based ink composition block the comb teeth of the ink holding member, and excess ink due to an increase in the internal pressure of the ink tank is removed. This is because it is possible to solve the problem that the ink cannot be held and the ink drops.

For the ink tank and the ink flow rate adjusting body provided in the writing instrument, it is necessary to use a material that does not react with the contained water-based ink composition and does not easily impair the performance of the ink composition itself. For this reason, resin is often used as the material for the ink tank and the ink flow rate regulator. However, the surface of such a resin is often hydrophobic, and the wettability with the water-based ink composition tends to be poor. Therefore, when using a resin ink tank or an ink flow rate regulator, it is necessary to particularly consider the ink reversibility in the ink tank and the ink dripping performance. As described above, the ink composition of the present invention containing the polyether amine can maintain an appropriate wettability even in an ink tank or an ink flow rate adjusting body made of a resin. Therefore, the water-based ink composition of the present invention can also be suitably used for a writing instrument provided with a resin ink tank and an ink flow rate regulator. In particular, it is more effective to use an aqueous ink composition containing the polyether amine having a surface tension of a 1% aqueous solution of polyether amine of 35 to 55 mN / m in an environment of 20 ° C. is there. As the resin used as the material of the ink tank and the ink flow rate regulator, polyethylene, polypropylene, polyethylene terephthalate, ABS, polycarbonate, polyimide, polyamide and the like are preferably used.

The ink tank of a writing instrument in which the water-based ink composition for a writing instrument of the present invention is used is directly inside the ink tank from an ink tank (ink cartridge) that can be detachably attached to the writing instrument body or an ink container such as an ink bottle. Examples thereof include an ink tank (converter) having a function of sucking ink.

For writing instruments equipped with a removable ink tank (ink cartridge) on the writing instrument body, the ink cartridge is discarded after using the contained water-based ink composition, so in consideration of economic efficiency, etc. Resin is often used, and as described above, the wettability with the water-based ink composition tends to deteriorate. Further, since the ink cartridge is provided in the barrel of the writing instrument and may be restricted by the size of the inner diameter due to the relationship with the diameter of the barrel, the fluidity of the ink in the ink cartridge tends to deteriorate. It is in. For this reason, in a writing instrument provided with an ink cartridge, it is necessary to particularly consider the ink reversibility in the ink cartridge. Since the ink composition of the present invention can maintain an appropriate wettability of a resin ink tank and has excellent ink reversibility in the ink tank, it can be used as a writing instrument provided with an ink cartridge as described above. Can also be preferably used.

Further, in a writing tool equipped with an ink tank (converter) having a function of directly sucking ink into the ink tank from an ink container such as an ink bottle, the ink in the ink tank is the same as the above ink cartridge. In addition to the problem of reversibility, with the conventional water-based ink composition, the ink foams when inhaled, and it is difficult to fill the entire inside of the converter with the water-based ink composition. However, as described above, since the aqueous ink composition containing the polyether amine is excellent in foam breaking property, the ink can be sucked into the converter to the end. Therefore, the water-based ink composition of the present invention can also be suitably used for a writing instrument provided with a converter.

Based on the above, the ink composition of the present invention containing the polyether amine is a writing instrument in which a comb-shaped ink holding member is arranged and a writing instrument provided with an ink tank (cartridge or converter) as an ink flow control body. Can be suitably used for.

<Colorant>
Examples of the colorant that can be used in the present invention include dyes and pigments that are usually used in water-based ink compositions for writing instruments.

The dye that can be used in the present invention is not particularly limited as long as it can be dissolved or dispersed in an aqueous medium. For example, various dyes such as acid dyes, basic dyes, reactive dyes, direct dyes, disperse dyes and food dyes can be mentioned, and these can be used alone or in combination of two or more.

Specifically, as the acid dye, C.I. I. Acid Red 18, C.I. I. Acid Red 51, C.I. I. Acid Red 52, C.I. I. Acid Red 87, C.I. I. Acid Red 92, C.I. I. Acid Red 289, C.I. I. Acid Orange 10, C.I. I. Acid Yellow 3, C.I. I. Acid Yellow 7, C.I. I. Acid Yellow 23, C.I. I. Acid Yellow 42, C.I. I. Acid Green 3, C.I. I. Acid Green 16, C.I. I. Acid Blue 1, C.I. I. Acid Blue 9, C.I. I. Acid Blue 22, C.I. I. Acid Blue 90, C.I. I. Acid Blue 239, C.I. I. Acid Blue 248, C.I. I. Acid Violet 15, C.I. I. Acid Violet 49, C.I. I. Acid Black 1, C.I. I. Acid Black 2, as a basic dye, C.I. I. Basic Orange 2, C.I. I. Basic Orange 14, C.I. I. Basic Green 4, C.I. I. Basic Blue 9, C.I. I. Basic Blue 26, C.I. I. Basic Violet 1, C.I. I. Basic Violet 3, C.I. I. Basic Violet 10, as a direct dye, C.I. I. Direct Red 28, C.I. I. Direct Yellow 44, C.I. I. Direct Blue 86, C.I. I. Direct Blue 87, C.I. I. Direct Violet 51, C.I. I. Direct Black 19, as an food coloring, C.I. I. Hood Yellow 3, C.I. I. Food black 2 and the like can be mentioned.

Further, the pigment that can be used in the present invention is not particularly limited as long as it can be dissolved or dispersed in an aqueous medium. Examples thereof include inorganic, organic, and processed pigments. Specific examples thereof include carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, quinophthalone, and slene. Examples thereof include triphenylmethane-based, perinone-based, perylene-based, gyoxazine-based, aluminum pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, and complementary color pigments. In addition, even if a microcapsule pigment obtained by encapsulating or solidifying a colored body in which a pigment is dispersed in a medium as a colored resin particle body in a shell made of a resin wall film forming substance by a known microencapsulation method or the like is used. good.

Further, as the colorant, the above pigments and dyes may be used alone or in combination of two or more. The content of the colorant in the water-based ink composition is preferably 0.1 to 8.0% by mass based on the total mass of the water-based ink composition. When the content of the colorant is within the above numerical range, deterioration of the ejection property of the water-based ink can be prevented, and when the water-based ink composition is used, good handwriting can be obtained.

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

<Others>
The water-based ink composition according to the present invention may contain various additives such as a water-soluble organic solvent, a pH adjuster, a moisturizer, a rust preventive, a preservative, and a chelating agent for the purpose of improving the physical properties and functions of the ink. Good.

Examples of the water-soluble organic solvent include (i) glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, or glycerin, and (ii) methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t. -Alcohols such as butanol, propanol alcohol, allyl alcohol, 3-methyl-1-butin-3-ol, ethylene glycol monomethyl ether acetate and other higher alcohols, and (iii) ethylene glycol monomethyl ether, ethylene glycol mono Examples thereof include glycol ethers such as ethyl ether, 3-methoxybutanol, or 3-methoxy-3-methylbutanol.
Among them, it is preferable to use diethylene glycol, ethylene glycol, glycerin or the like, which can efficiently obtain the effect of polyetheramine because it has good compatibility with polyetheramine and can exist stably.
The content of the water-soluble organic solvent in the water-based ink composition is preferably 0.1 to 10% by mass based on the total mass of the water-based ink composition.

Examples of the pH adjuster include inorganic salts such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide and sodium acetate, organic basic compounds such as alkanolamines such as triethanolamine and diethanolamine, lactic acid and citric acid. In consideration of the stability with the polyether amine, it is preferable to use an alkanolamine, and more carefully, it is preferable to use a weakly basic triethanolamine. These neutralizers may be used alone or in combination of two or more. The content of the pH adjuster is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of the aqueous ink composition.

Examples of the moisturizer include urea, sorbitol, and the like in addition to the water-soluble organic solvent. The content of the moisturizer is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of the water-based ink composition. Examples of the rust preventive include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrate, diisopropylammonium nitrate, sodium thiosulfate, ethylenediamine tetraacetate, saponin, and dialkylthiourea. Further, as the water-soluble resin, acrylic resin, alkyd resin, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol and the like can be used. Further, as the resin emulsion, an emulsion containing an acrylic resin, a urethane resin, a styrene-butadiene resin, a polyester resin, a vinyl acetate resin or the like can be added.

Further, a surfactant other than the polyether amine may be contained. Specific examples thereof include fluorine-based surfactants, nonions, anions, cationic surfactants, and silicone-based surfactants.

<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, for production.

<Writing instruments>
The water-based ink composition of the present invention can be used for writing instruments such as marking pens and ballpoint pens with fiber chips, felt-tips, plastic chips or ballpoint pens as writing tips, and fountain pens with metal writing tips.

Further, the writing instrument that can be used with the water-based ink composition of the present invention may be one that is directly filled with the ink composition, and is provided with an ink tank that can be filled with the ink composition. It may be.

Above all, the water-based ink composition for writing instruments of the present invention can be suitably used for writing instruments provided with an ink tank. In particular, the ink tank has a function of being able to directly suck ink into the ink tank from an ink tank (ink cartridge) in which the ink tank can be detachably attached to the writing instrument body and an ink container such as an ink bottle. It can be suitably used for a writing instrument equipped with an ink tank (converter) having an ink tank. Since the ink tank as described above may be provided in the barrel of the writing instrument, the inner diameter of the ink tank is likely to be restricted. Therefore, the water-based ink composition does not easily flow in the ink tank, and it is necessary to pay particular attention to the ink reversibility in the ink tank. Since the water-based ink composition of the present invention is excellent in ink reversibility in the ink tank, it can be suitably used for a writing instrument provided with the above-mentioned ink tank, and good writing property and handwriting can be obtained. Can be done.
Further, when the material of the ink tank is a resin, the ink tank tends to have poor wettability with the water-based ink composition, so that it is necessary to further consider the ink reversibility in the ink tank. Even in such a case, the ink composition of the present invention can maintain an appropriate wettability in the ink tank and is excellent in ink reversibility in the ink tank. Therefore, even when the material of the ink tank is a resin, the ink composition of the present invention can be preferably used, and good writeability and handwriting can be obtained.

The writing instrument that can be used with the water-based ink composition of the present invention is a cap type having a cap covering the writing tip, a knock type, a rotary type, a sliding type, or the like, which can accommodate the writing tip in a barrel. There may be. In particular, in the infestation type writing instrument, measures against ink leakage due to the ink dripping phenomenon are more important, so that the water-based ink composition of the present invention can be preferably used.

Further, the ink supply mechanism of the writing tool that can be used by the water-based ink composition of the present invention is not particularly limited. For example, (1) an ink guide core made of a fiber bundle or the like is provided as an ink flow rate regulator. , A mechanism for supplying the water-based ink composition to the writing tip, (2) A mechanism in which a comb-shaped ink holding member is arranged as an ink flow control body, and a mechanism for supplying the water-based ink composition to the writing tip, (3) A valve mechanism A mechanism for supplying the water-based ink composition to the writing tip of the writing tip, and (4) a mechanism for directly supplying the water-based ink composition to the writing tip without the ink flow rate adjusting body can be mentioned.

Among the above, a writing instrument provided with an ink flow rate regulator in the ink supply mechanism often uses an aqueous ink composition having a high viscosity index n and a low viscosity due to the characteristics of the supply mechanism. In this case, it is necessary to keep the surface tension of the water-based ink composition within an appropriate range in order to obtain good ink ejection property and writeability from the pen tip.
For this reason, it is common to add a wettability imparting agent to the water-based ink composition, but when the wettability imparting agent is added, the permeability to the paper surface is extremely increased, and the handwriting is blurred. Problems such as strike-through will occur. The water-based ink composition of the present invention can improve the ink ejection property and the writing property from the pen tip without extremely lowering the surface tension, and can suppress the handwriting bleeding and strike-through on the paper surface. The ink composition can be suitably used for a writing instrument provided with an ink flow rate regulator in the ink supply mechanism as described above. In particular, in a writing instrument provided with a comb-tooth-shaped ink holding member arranged as an ink flow rate adjusting body and a mechanism for supplying an aqueous ink composition to the writing tip, the above-mentioned problems tend to occur. It is more effective to use the ink composition of.

In addition, when resin is used as the material of the ink flow rate regulator, the hydrophobicity becomes too strong due to the influence of the type of resin and additives such as mold lubricant used at the time of molding, and the ink becomes wet with the water-based ink composition. There may be a lack of sex. Therefore, it is more preferable to modify the surface of the ink flow rate adjusting body with a surface modifier because stable performance of the ink flow rate adjusting body can be obtained. Examples of the surface modifier include resins and surfactants. Specific examples thereof include copolymers containing vinyl acetate and acrylic acid esters, surfactants having an acetylene bond, and succinic acid-based surfactants. It is preferable to use a surfactant such as a silicone-based surfactant. An ink flow rate regulator surface-modified with a surface modifier such as these can exhibit good wettability with respect to water, that is, an aqueous ink composition. Therefore, the water-based ink composition of the present invention can be used in a writing instrument provided with such a surface-modified ink flow rate adjuster to obtain a remarkable effect.

In a fountain pen, a comb-shaped ink holding member is arranged as an ink flow rate adjusting body, and a mechanism for supplying an aqueous ink composition to the writing tip is provided. Therefore, in order to obtain good ink ejection property, writeability, and handwriting from the pen tip, it is necessary to keep the surface tension, viscosity, and viscosity index n of the aqueous ink composition within an appropriate range.
Furthermore, the ink tank of the fountain pen can be used to suck ink directly into the ink tank from an ink tank (ink cartridge) that can be detachably attached to the writing tool body or from an ink container such as an ink bottle. There is a high possibility that an ink tank (converter) having a function capable of performing the ink tank is used, and the material of the ink tank is resin.
Based on the above, the surface tension of the water-based ink composition is properly adjusted, the wettability to the ink tank and the ink flow control body is maintained appropriately, the ink reversibility in the ink tank and the ink dripping phenomenon are suppressed. Further, the ink composition of the present invention, which is excellent in writability and can obtain a good writing stroke without bleeding or strike-through, can be suitably used as a water-based ink composition for a fountain pen.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
Raw materials other than the coloring material were mixed by propeller stirring with the following raw materials and blending amounts to obtain a base liquid. Then, a colorant was added to the base liquid and mixed by stirring with a propeller to obtain a water-based ink composition for writing instruments. The viscosity of the obtained aqueous ink composition is measured with a B-type rotational viscometer (model: BLII, rotor: BL adapter, manufactured by Toki Sangyo Co., Ltd., sample volume 20 ml), and the viscosity index n is calculated based on the viscosity. did. Specifically, the viscosity at 20 ° C. and a rotation speed of 12 rpm was 1.20 mPa · s, and the viscosity at 20 ° C. and a rotation speed of 60 rpm was 1.51 mPa · s. From these viscosities, the viscosity index n was calculated to be 1.14. The surface tension of the obtained water-based ink composition was measured by a surface tension measuring instrument (platinum plate, vertical plate method, manufactured by Kyowa Interface Science Co., Ltd. in an environment of 20 ° C.) and found to be 43.3 mN / m. It was. Further, as a result of measuring the pH of the aqueous ink composition at 20 ° C. using an IM-40S type pH meter (manufactured by DKK-TOA CORPORATION), the pH was 9.12.
・ Colorant 3.5% by mass
(Bayscript Black SP, solid content: 30%)
-Polyetheramine 1.0% by mass
(Polyoxyethylene-stearylamine, trade name: Nymine S-220, HLB value 15.4)
・ PH adjuster 1.0% by mass
(Triethanolamine)
・ Water-soluble organic solvent 3.0% by mass
(Diethylene glycol)
・ Water 91.5% by mass

<Examples 2 to 9, Comparative Examples 1 to 6>
Aqueous ink compositions of Examples 2 to 9 and Comparative Examples 1 to 6 by changing the types and amounts of the components to be blended with respect to Example 1 as shown in Tables 1 and 2. Got

<Making a test pen>
The water-based ink compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 6 were applied to a resin converter (Pilot Corporation, CON-70, ink capacity 1.1 ml) with the converter opening facing upward. 0.5 ml was injected in the state of. This converter is used as an ink flow controller on a writing instrument (Pilot Corporation, fountain pen, Kakuno) with a pen tip in the form of a fountain pen on which a comb-shaped ink holding member (surface modified) is arranged. I put it on with the tip facing up. Use this writing instrument as a test pen.

<Test 1 = Ink reversal test in ink tank>
The test pen was turned upward and all the filled water-based ink composition was dropped on the opposite side of the pen tip in the ink tank. After that, when the pen tip was gently turned downward, it was visually confirmed that the water-based ink composition flowed down to the pen tip side in the ink tank, and the ink reversal performance in the ink tank was evaluated according to the following criteria. .. The evaluation results obtained are summarized in Tables 1 and 2.
◯: Within 1 second, all the water-based ink composition flowed down to the pen tip side of the ink tank.
Δ: Most of the water-based ink composition flowed down to the pen tip side of the ink tank within 1 second, but part of it did not flow down and remained on the wall surface in the ink tank.
X: No water-based ink composition flowed down to the pen tip side of the ink tank even after 1 second had passed.

<Test 2 = Written test>
The test pen used in Test 1 was turned downward for a while, and the filled water-based ink composition was allowed to flow into the pen tip so that it could be written. In that state, 10 consecutive circles were written on an arbitrary paper surface, the handwriting was confirmed, and the writing performance was evaluated according to the following criteria. The evaluation results obtained are summarized in Tables 1 and 2. The evaluation was performed using JIS P3201 writing paper A as the writing test paper.
◯: Good handwriting was obtained with no bleeding, blurring, or strike-through.
×: Bleeding, blurring, strike-through, etc. were confirmed in the handwriting.

<Test 3 = Pressure resistance change test (ink drop resistance test)>
The test pen used in Test 2 was placed with the pen tip facing downward and allowed to stand in a decompression desiccator. In this state, the pressure inside the desiccator was reduced to 70 mmHg for 5 minutes, and then the test pen was left in the desiccator for another 5 minutes while maintaining the reduced pressure state of 70 mmHg. At this time, it was confirmed whether or not the water-based ink composition was blown out from the tip of the test pen, and the presence or absence of ink dripping was confirmed, and the ink dripping performance was evaluated according to the following criteria.
◯: The water-based ink composition did not blow out from the pen tip, and the ink did not drop.
Δ: When the pressure inside the desiccator was reduced to 70 mmHg in 5 minutes, no blowout of the water-based ink composition was observed from the pen tip and no ink dripping occurred, but the reduced pressure state of 70 mmHg was maintained for 5 minutes. During this period, a small amount of the water-based ink composition was blown out from the pen tip, and some ink dripping occurred. However, there was no problem in practical use.
X: When the pressure inside the desiccator was reduced to 70 mmHg in 5 minutes, the water-based ink composition was blown out from the pen tip, and the ink dropped.

As shown in Tables 1 and 2, the water-based ink compositions of Examples 1 to 9 have good ink reversibility in the ink tank based on the results of <ink reversal test in the ink tank>. From the result of <Writing test>, it has excellent writing performance that can obtain good writing stroke, and from the result of <Pressure resistance change test (ink drop resistance test)>, the ink of ink even in a sudden pressure change. It was confirmed that no dripping was observed and the ink had good dripping performance.
Based on the above, the water-based ink of Examples 1 to 9, which contains water, a colorant, and a polyether amine having an HLB value of 10 to 20, and has a surface tension of 35 to 55 mN / m at 20 ° C. Good results were obtained in all of the <ink reversal test in the ink tank>, <writing test>, and <pressure resistance change test (ink dripping test)>, and the ink composition was a water-based ink composition for writing instruments. It turned out to be an excellent product. Further, it was found that the writing instrument containing the water-based ink compositions of Examples 1 to 9 can obtain good writing performance and handwriting.

The ink composition of the present invention can be used as a water-based ink composition for various writing tools such as fountain pens, ballpoint pens, brush pens, calligraphy pens, and marking pens. In particular, since the ink reversibility in the ink tank and the ink dripping performance are improved, it can be suitably used for a writing instrument provided with an ink tank and an ink flow rate adjusting body in the ink supply mechanism. Further, as an ink flow rate adjusting body, it can be effectively used in a writing instrument in which a comb-shaped ink holding member is arranged.

Claims (5)

As an ink flow control body for adjusting the ink flow rate, a comb-shaped ink holding member is arranged, and a detachably replaceable ink tank or an ink tank having a function of sucking ink is provided in the barrel. A water-based ink composition for writing tools used for a perpetual brush that supplies the ink contained in the ink tank to the tip of the writing, and the water-based ink composition for writing tools has water, a colorant, and an HLB value of 10 to 20. What der average ethylene oxide addition mole number (EO number) is 13 to 30, the surface tension at the time of a 1% aqueous solution, under 20 ° C. environment, 35~55mN / m der Ru polyetheramine A water-based ink composition for writing tools, wherein the surface tension of the water-based ink composition for writing tools at 20 ° C. is 35 to 55 mN / m. Using a B-type rotational viscometer, the ink viscosity measured at a rotation speed 60 rpm, 20 ° C. is a 1 to 3 MPa · s, a writing instrument for aqueous ink composition according to claim 1. Viscosity index n at 20 ° C. is from 0.9 to 1.2, according to claim 1 or writing instrument for water-based ink composition according to 2. The water-based ink composition for writing instruments according to any one of claims 1 to 3, wherein the ink flow rate adjusting body and the ink tank are made of resin. Wherein the writing instrument for aqueous ink composition according is housed in any one of claims 1 to 4, fountain pen.