JP2021006626A - Aqueous ink composition for writing instruments, and writing instrument including the same - Google Patents

Abstract

To provide an aqueous ink composition for writing instruments having excellent handwriting water resistance and also excellent writing performance, and a writing instrument including the same.SOLUTION: There is provided an aqueous ink composition for writing instruments containing MQ resin, a colorant, and water. There is also provided a writing instrument including the same.SELECTED DRAWING: None

Description

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

Since the ink composition for writing instruments is used in a normal living environment, the obtained handwriting is likely to come into contact with water droplets or sweat. For this reason, the handwriting may be blurred or thinned by water droplets or sweat, or may disappear if it becomes worse, and the improvement of the water resistance of the handwriting should be solved in the ink composition for writing instruments. It is an issue.
In particular, the handwriting obtained by the water-based ink composition using water as the solvent is easily affected by water droplets and sweat, and the improvement of the water resistance of the handwriting is improved in the oil-based ink composition using an organic solvent as the solvent. In comparison, it is more strongly sought after.
Therefore, in order to solve the above problems, it has been proposed to use polymer dyes and pigments as colorants and to add various resin agents such as acrylic resins and urethane resins as water resistance imparting agents. (Patent Documents 1, 2, etc.)
The ink composition described in Patent Document 1 uses a polymer dye, and although the water resistance of the handwriting is improved to some extent, it is not sufficiently satisfactory and the color development of the handwriting is inferior. Occurs.
The ink composition described in Patent Document 2 contains a pigment and an acrylic resin, and although the water resistance of the brush stroke can be improved, the pigment may aggregate depending on the type of the pigment. Poor ink tracking causes the strokes to be faint or hollow, and the strokes cannot be obtained due to the inability to write. Also, the colorant discolors and the strokes develop in the desired color. It was sometimes difficult to obtain satisfactory writing performance, such as not being able to obtain it.
In particular, when colored resin particles obtained by coloring resin particles with a coloring material such as a dye are used, if the water resistance is improved, the writing performance tends to be defective as described above due to the influence of the additives used. It is in. However, the colored resin particles can express various colors such as general colors and fluorescent colors with good color development, and are effectively used. Therefore, in a water-based ink composition for writing instruments using colored resin particles, improving the water resistance of handwriting while having excellent writing performance is a major problem to be solved.

Patent No. 2043996 Japanese Unexamined Patent Publication No. 58-080368

An object of the present invention is to solve the above-mentioned problems, to provide a water-based ink composition for a writing instrument having excellent handwriting water resistance and excellent writing performance, and to provide a writing instrument using the same. Is to provide.

In order to solve the above problems, the present invention
"1. A water-based ink composition for writing instruments, which comprises MQ resin, a colorant, and water.
2. 2. The water-based ink composition for writing instruments according to item 1, wherein the content of the MQ resin is 0.01% by mass to 30% by mass based on the total mass of the water-based ink composition for writing instruments.
3. 3. The water-based ink composition for writing instruments according to item 1 or 2, further comprising a polyalkylene oxide adduct of an aliphatic alcohol.
4. A writing instrument comprising the water-based ink composition for a writing instrument according to any one of paragraphs 1 to 3.
5. The writing instrument according to item 4, which is a marking pen. ".

According to the present invention, even if water droplets adhere to the obtained handwriting or the handwriting is immersed in water, the handwriting does not bleed, become thin, or disappear, and excellent handwriting water resistance is obtained. We provide a water-based ink composition for writing instruments that also exhibits excellent writing performance, such as obtaining handwriting with excellent color development clarity in the desired color without blurring or hollowing out, and writing instruments using it. can do.

Hereinafter, embodiments of the present invention will be described in detail. In addition, in this specification, "part", "%", "ratio", etc. indicating a composition are based on mass unless otherwise specified, and the content rate is a configuration based on the mass of the ink composition. It is the mass% of the component.

<Aqueous ink composition for writing instruments>
The water-based ink composition for writing tools (hereinafter, sometimes referred to as an ink composition) according to the present invention is characterized by containing an MQ resin, a colorant, and water.
Hereinafter, the constituent components of the ink composition of the present invention will be described in detail.

<MQ resin>
The ink composition of the present invention comprises an MQ resin.
The MQ resin is a silicone resin containing a siloxane unit (M unit) represented by the general formula (1) and a siloxane unit (Q unit) represented by the general formula (2) as main constituents.

Ｒは１価の炭化水素基を表す。

R represents a monovalent hydrocarbon group.

The M unit may be expressed as [R ₃ SiO _1/2 (R represents a monovalent hydrocarbon group)], and the Q unit may be expressed as [SiO _4/2 ].

Further, the M unit may be represented by the formula (3), and the Q unit may be represented by the formula (4).

The MQ resin can form a film having excellent water repellency, works effectively as a water resistance imparting agent, and can impart water resistance to the obtained handwriting.
This is because when MQ resin is added to the ink composition, a water-repellent film is formed on the surface of the obtained handwriting, and the colorant is firmly fixed to the writing surface by the film. It is presumed that this is because the contact between the colorant and water can be prevented.
Therefore, in the ink composition of the present invention containing MQ resin, even if water droplets adhere to the obtained handwriting or the handwriting is immersed in water, the outflow of the colorant is suppressed, and the handwriting becomes blurred or thin. It is possible to achieve excellent handwriting water resistance without becoming or disappearing.
In addition, the film formed by MQ resin does not easily affect the color development of handwriting. Therefore, the ink composition of the present invention can leave a clear color-developed handwriting while having excellent water resistance. In addition, the MQ resin is stable with respect to the colorant and can suppress the colorant from aggregating or discoloring. Therefore, in the ink composition of the present invention, good handwriting without blurring or hollowing out can be obtained without causing poor tracking due to agglomerates, and the obtained handwriting has a desired color and color clarity. It is also possible to achieve excellent handwriting performance, such as being in an excellent state. Furthermore, it is possible to maintain this excellent writing performance for a long period of time.

The MQ resin used in the present invention is not particularly limited as long as it is a silicone resin containing M units and Q units as main constituents as described above. The MQ resin may have a structural unit other than the M unit and the Q unit, but the number of the structural units other than the M unit and the Q unit is 30% or less based on all the structural units in the MQ resin. It is preferably present, more preferably 10% or less, and most preferably 0%, that is, the MQ resin is composed of M units and Q units.

Further, as the MQ resin, it is preferable to use an MQ resin in which the molar ratio of M units to Q units (M units / Q units) is 0.5 to 1.5.
When the molar ratio of M units to Q units is within the above numerical range, it is easy to improve handwriting water resistance while maintaining excellent stability over time and writing performance.

Further, in the formula (1) representing the above-mentioned siloxane unit (M unit), in the formula (3), R is a linear or branched alkyl group of C _1-10 or an aryl group of C _6-15 . The alkyl group and the aryl group may be substituted with an amino group, an epoxy group or a carboxy group, but are preferably unsubstituted. As R, specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isopropyl group, isobutyl group, 2-ethylhexyl group, phenyl. Examples thereof include a group, a trill group, a xsilyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group and the like, but more preferable of these is a C _1-5 linear or branched alkyl group or a phenyl group. Yes, more preferably a C _1-5 linear or branched alkyl group. In particular, a methyl group is most preferable in consideration of stable presence in water-based ink, excellent stability over time, and further improvement in writing performance and handwriting water resistance.

Furthermore, the MQ resin having the following formula (5) is also a preferable embodiment.

但し、ａ：１〜３、ｂ：０．５〜８

However, a: 1 to 3, b: 0.5 to 8

Moreover, it is preferable that the MQ resin used in the present invention is uniformly dispersed in the composition. In this case, the MQ resin exists in the form of particles without being dissolved in the composition, and at the time of writing, water evaporates and the particles bind to each other to form a film.
The average particle size of the MQ resin in this case is preferably 0.01 μm to 2.0 μm, and more preferably 0.05 μm to 1.5 μm.
Here, in the present invention, the average particle size of MQ resin is a volume-based average particle size measured by a laser diffraction method. The average particle size of the MQ resin can be measured by the same method as the average particle size of the above-mentioned contents.

Further, when producing the ink composition according to the present invention, the MQ resin may be added in the form of a dispersion dispersed in water (using a dispersant if necessary), for example, an emulsion. .. Then, it is also a preferable form that the MQ resin is added to the ink composition in a state of being emulsified and dispersed in an aqueous medium (in an emulsion state) in advance. This is because the MQ resin tends to be stably and uniformly present in the water-based ink, and a film having excellent water repellency can be uniformly formed on the handwriting surface. For this reason, it is possible to leave a handwriting with excellent water resistance while having excellent color vividness without color unevenness. In addition, the stability over time can be improved.

Further, in the present invention, the MQ resin is preferably emulsified and dispersed in an aqueous medium using a dispersant. As a result, the MQ resin can be more stably and uniformly present in the ink, and the film formation can be improved.
As the dispersant, an anionic surfactant and a nonionic surfactant are preferably used. It is particularly preferable to use a nonionic surfactant, which tends to have little adverse effect on other additives and also has a tendency to have little influence on the formation of a water-repellent film of MQ resin. Therefore, in the present invention, it is preferable to use an emulsified dispersion of nonionic MQ resin.
As the anionic surfactant, a sodium sulfonic acid salt compound or the like can be preferably used, and as the nonionic surfactant, a polyoxyalkylene alkyl ether or the like is preferably used.

Further, in the present invention, it is preferable that the silicone oil is further contained. Although the reason is not clear, the inclusion of silicone oil makes it easier for the MQ resin to exist more stably in the water-based ink, and makes it possible to form the MQ resin film thinner and more uniformly on the brush stroke surface. This is because it is possible to obtain a brush stroke having excellent water resistance and color clarity.
The silicone oil preferably has a kinematic viscosity of 1 cSt to 1000 cSt, and more preferably 1 cSt to 100 cSt.
Further, in the present invention, it is particularly effective to use the MQ resin in a state of being dissolved in the silicone oil and then emulsified and dispersed in water to improve stability over time, water resistance and color clarity. You can get a particularly good handwriting.

Examples of commercially available products containing MQ resin include KM-9717 (nonvolatile content 60% by mass, anionic, low-viscosity silicone content, manufactured by Shin-Etsu Chemical Co., Ltd.), X-52-8005 (nonvolatile content 58 mass). %, Nonionic, low-viscosity silicone-containing, manufactured by Shin-Etsu Chemical Co., Ltd.), R-2701 (active ingredient 40% by mass, anionic, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) and the like.

The content of MQ resin in the ink composition of the present invention is preferably 0.01% by mass to 30% by mass based on the total mass of the ink composition, and exhibits better handwriting water resistance and writing performance. be able to. In addition, excellent stability over time can be obtained.
If it is 0.01% by mass or more, the effect of the MQ resin as a water resistance imparting agent can be sufficiently obtained, and if it is 30% by mass or less, the MQ resin is stably present in the ink. In addition to being easy to obtain and excellent stability over time, the thickness of the film formed by the MQ resin can be maintained at an appropriate level, and a handwriting with excellent color development and sharpness can be obtained.
Considering further improvement of handwriting water resistance, it is more preferably 0.02% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 1% by mass or more.
Further, considering that the viscosity of the ink composition is kept low, excellent ink ejection property is maintained and good handwriting is left, it is more preferably 25% by mass or less, and more preferably 20% by mass or less. Is more preferable, 15% by mass or less is particularly preferable, 10% by mass or less is most preferable, and 6% by mass or less is particularly preferable.
The MQ resin can also be used as one kind or a mixture of two or more kinds.

When silicone oil is further contained, the total content of MQ resin and silicone oil is 0.05% by mass based on the total mass of the ink composition, considering the improvement of writing water resistance and writing performance. It is preferably ~ 25% by mass, more preferably 0.1% by mass to 20% by mass, and most preferably 0.2% by mass to 15% by mass.

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

The pigment is not particularly limited as long as it can be dispersed in a solvent. For example, inorganic pigments, organic pigments, processed pigments, etc. are mentioned, and specific examples thereof include carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, quinophthalone, and slene. Examples thereof include system, triphenylmethane type, perinone type, perylene type, dioxazine type, aluminum pigment, pearl pigment, fluorescent pigment, phosphorescent pigment and the like. In addition, colored resin particles in which resin particles are colored with a dye or the like, or a colored body in which a coloring material is dispersed in a medium are encapsulated in a shell made of a resin wall film forming substance by a known microencapsulation method or the like. A solid-solubilized microcapsule pigment may be used.
As the pigment, an aqueous dispersion pigment product or the like finely and stably dispersed in an aqueous medium using a pigment dispersant may be used. Examples of the pigment dispersant include water-soluble resins, nonionic surfactants, anionic surfactants, and cationic surfactants.

The dye is not particularly limited as long as it can be dissolved in a solvent. For example, direct dyes, acid dyes, basic dyes, gold-containing dyes, various salt-forming type dyes, and the like can be adopted.
These pigments and dyes may be used as one or a mixture of two or more.

In the present invention, it is preferable to use a pigment. By using a pigment, it is possible to leave a handwriting with better water resistance and color development.
This is because the film formed by the MQ resin firmly fixes the pigment on the writing surface, and the film can prevent the pigment from coming into contact with water and sufficiently prevent the pigment from flowing out from the handwriting. Infer.

Further, among the pigments, it is effective to use colored resin particles obtained by coloring the resin particles with a coloring material such as a dye because it is easy to obtain a handwriting capable of expressing various colors with good color development.
However, on the other hand, the colored resin particles are affected by other additives and agglomerate or discolor and cannot express the desired color, resulting in excellent handwriting performance and stability over time. It is also difficult to obtain sex.
However, the MQ resin used in the present invention is stable with respect to the colored resin particles, and can impart excellent water resistance to the handwriting without the colored resin particles agglomerating and discoloring. Therefore, in the present invention containing MQ resin, the use of colored resin particles can express various colors with good color development while having good stability over time, and has good handwriting without blurring or hollowing out. Is effective because it can be left as having excellent water resistance.
Further, the colored resin particles are spherical particles, and the aggregate thereof is a homogeneous aggregate as compared with a general pigment. For this reason, the MQ resin film tends to be more uniformly formed on the handwriting surface formed by the colored resin particles. Therefore, when the colored resin particles are used, it is easy to impart water resistance to the handwriting without impairing the color clarity of the handwriting, and from this viewpoint, it is preferable to use the colored resin particles in the present invention. ..
Further, among the colored resin particles, the colored resin particles (fluorescent colored resin particles) colored with a fluorescent dye can leave a brush stroke having fluorescence that does not hide the base with good coloring. Therefore, it can be suitably used as a colorant for an ink composition for a marking pen and is useful. However, the fluorescent colored resin particles are further affected by the additive and tend to be easily aggregated or discolored. However, since MQ resin is stable even in these fluorescent colored resin particles, it is difficult for the fluorescent colored resin particles to aggregate or discolor, and a good water-repellent coating is obtained without impairing the fluorescent color development property. It can be formed on the surface of the handwriting. Therefore, in the present invention, the use of fluorescent colored resin particles is effective because excellent handwriting water resistance and writing performance can be obtained.

Conventionally known colored resin particles can be used. Specifically, resin particles such as amino resin, acrylic resin, styrene resin, polyester resin, and polyamide resin are used as a coloring material such as a dye. Examples include colored ones. Among them, those obtained by coloring styrene resin particles with a coloring material, which are compatible with MQ resin and easily obtain excellent stability over time, are preferable, and further, styrene-acrylonitrile resin particles are colored with a coloring material. It is more preferably used.
Further, the coloring material used for the colored resin particles is not limited as long as the resin particles can be colored. Conventionally known dyes and pigments can be appropriately used depending on the resin particles of the base material, but it is preferable to use dyes that can easily obtain better color development, and basic dyes, acid dyes, direct dyes, and dispersions are preferable. Dyes, solvent dyes and the like can be used.
As described above, in the present invention, the fluorescent colored resin particles can be preferably used, but in this case, it is preferable to use a fluorescent dye as the coloring material for coloring the resin particles. Specific examples thereof include a basic dye having a xanthene skeleton, a triaryl skeleton, or an azo skeleton, or a disperse dye. Of these, a basic dye having a xanthene skeleton or an azo skeleton is preferable because the handwriting is more visible. Examples of such fluorescent dyes include Direct Yellow 85, Basic Yellow 1, 40, Basic Red 1, 1: 1, Basic Violet 10, 11: 1, Acid Yellow 7, Acid Red 92, Acid Blue 9, and Dis. Perth Yellow 82, 121 and the like can be mentioned.

Specific examples of commercially available products containing colored resin particles include Shinroihi color series (manufactured by Shinroihi Co., Ltd.), Lumicol series (manufactured by Nippon Fluorescent Chemical Co., Ltd.), and LM series (Fuji dye (Fuji dye). Co., Ltd.), Epocolor series (manufactured by Nippon Catalyst Co., Ltd.), etc.

The average particle size of the colored resin particles is preferably 0.01 μm to 5 μm, and more preferably 0.05 μm to 1 μm. This is because when the average particle size of the pigment is within the above numerical range, it is easy to obtain a handwriting with clear color development, and it is easy to improve the dispersion stability of the pigment. The average particle size of the colored resin particles is standardized using, for example, a dynamic light scattering type (DLS) particle size distribution measuring device (trade name: Nanotrack NANO-flex, manufactured by Microtrack Bell Co., Ltd.). It can be measured by the particle size (D50) when the volume cumulative of the particle size distribution measured by the dynamic light scattering method is 50%, based on the numerical value calibrated using the sample or another measuring method.
In the present specification, the "average particle size" of the colored resin particles refers to the volume-based average particle size unless otherwise specified.

The content of the colorant in the ink composition of the present invention is preferably 0.1% by mass to 50% by mass, and preferably 1% by mass to 30% by mass, based on the total mass of the ink composition. More preferably, it is 5% by mass to 20% by mass. When the content of the colorant is within the above numerical range, the color clarity of the ink composition and the handwriting formed by using the ink composition can be well maintained without deteriorating the ink ejection property.

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

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

In the present invention, it is preferable that the water-soluble organic solvent is further contained. As the water-soluble organic solvent, those used in conventional water-based ink compositions for writing instruments can be used.
For example, (i) glycols such as ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, or glycerin, (ii) methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol. , Propagil alcohol, allyl alcohol, 3-methyl-1-butin-3-ol, alcohols such as ethylene glycol monomethyl ether acetate and other higher alcohols, and (iii) ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Examples thereof include glycol ethers such as 3-methoxybutanol or 3-methoxy-3-methylbutanol. These can be used as one kind or a mixture of two or more kinds.

In the present invention, it is preferable to use a polyhydric alcohol solvent among the water-soluble organic solvents. This can impart the hygroscopic effect of the polyhydric alcohol solvent to the ink composition without impairing the water-repellent film forming ability of the MQ resin, and can effectively suppress the evaporation of water in the ink from the pen tip. Because.
Therefore, even if the pen tip is exposed to the atmosphere for a while, the ink is discharged smoothly from the writing, and a uniform handwriting can be left, and the writing performance is also excellent.

In the present invention, it is preferable to select and use one or more of ethylene glycol, diethylene glycol, butylene glycol, and glycerin among the polyhydric alcohol solvents, and improve the writing performance while maintaining excellent handwriting water resistance. In consideration of the above, it is more preferable to use glycerin.

The content of the water-soluble organic solvent is preferably 0.1% by mass to 40% by mass based on the total mass of the ink composition.
Considering that the writing performance and the handwriting drying property are improved in a well-balanced manner while maintaining excellent handwriting water resistance, the content is preferably 0.5% by mass to 40% by mass, preferably 0.5% by mass to 15% by mass. Is more preferable.

Further, the ink composition of the present invention preferably contains a polyalkylene oxide adduct of an aliphatic alcohol.
By using a polyalkylene oxide adduct of an aliphatic alcohol, the paper permeability of the ink composition is improved without inhibiting the formation of a water-repellent film of MQ resin, and the dryness of the handwriting formed on the paper surface is improved. it can.
Therefore, in the present invention, by further containing the polyalkylene oxide adduct of the aliphatic alcohol, the handwriting water resistance and the handwriting drying property are excellent, and further, the polyalkylene oxide adduct of the aliphatic alcohol is an ink. Since it is possible to suppress the agglomeration of the colorants by adsorbing to the colorants contained in the composition, the stability over time can be improved and stable ink fluidity can be achieved.

As described above, the polyalkylene oxide adduct of the aliphatic alcohol used in the ink composition of the present invention has good handwriting drying property and stability of the colorant. However, as the polyalkylene oxide, ethylene is used. Examples thereof include substances formed from oxides, propylene oxides, butylene oxides and the like, which may be formed from a single type of alkylene oxide group or may be formed from a plurality of types of alkylene oxide groups, depending on the degree of polymerization. There is no limit.
Furthermore, when the polyalkylene oxide is formed from a plurality of types of alkylene oxide groups, the polyalkylene oxide may be a random polymer, an alternating polymer, or a block polymer.

Further, as the aliphatic alcohol, substances having various structures can be mentioned. For example, an alcohol having a linear structure or a branched structure, a saturated alcohol or an unsaturated alcohol may be used, and a unit price alcohol or a polyvalent alcohol may be used. Alcohol may be used, but as the aliphatic alcohol, an aliphatic alcohol having 8 to 15 carbon atoms is particularly preferable.
Further, the polyalkylene oxide adduct of the aliphatic alcohol is more preferably a polyalkylene oxide adduct of the aliphatic alcohol having an HLB value of 10 to 16.
Particularly preferably, it is a polyalkylene oxide adduct of the aliphatic alcohol having the carbon number, and among the substances having the HLB value, the substance having the structure represented by the following formula (6) or formula (7). is there.

ここで、Ｒ^１はアルキレン基を示し、Ｒ^２は脂肪族炭化水素基を示す。ｎは２以上の整数である。Ｒ^２の脂肪族炭化水素基が有する炭素数は８〜１５である。

Here, R ¹ represents an alkylene group and R ² represents an aliphatic hydrocarbon group. n is an integer of 2 or more. The number of carbon atoms included in the aliphatic hydrocarbon group R ² is 8-15.

ここで、Ｒ^３〜Ｒ^６は脂肪族炭化水素基を示し、Ｒ^７〜Ｒ^８はアルキレン基を示す。ｍ、ｐは０以上の整数を示し、ｍ、ｐの双方が０の場合を含まない。Ｒ^３〜Ｒ^６の脂肪族炭化水素基に含まれる炭素数の総和は４〜１１である。

Here, R ^{3 to} R ⁶ represent an aliphatic hydrocarbon group, and R ^{7 to} R ⁸ represent an alkylene group. m and p indicate integers of 0 or more, and do not include the case where both m and p are 0. The total number of carbon atoms contained in the aliphatic hydrocarbon groups of R ^{3 to} R ⁶ is 4 to 11.

By setting the carbon number of the aliphatic alcohol in the above range, the paper permeability of the ink composition can be further improved, it becomes easy to suppress ink bleeding during writing, and the poly of the aliphatic alcohol is further improved. By setting the HLB value of the alkylene oxide adduct in the range of 10 to 16, it becomes easy to improve the dissolution stability of the polyalkylene oxide adduct of the aliphatic alcohol.
Among such substances, the substances having the structures of the formulas (6) and (7) have good compatibility with the MQ resin, and improve the paper permeability of the ink composition while imparting water resistance to the handwriting. Further, it is preferably used because it is excellent in suppressing ink bleeding. Further, since the substance having the structure of the formula (6) is particularly excellent in dissolution stability, it is more preferably used in the ink composition of the present invention.
The HLB value is a numerical value based on the Griffin method, and refers to a value calculated by the following formula (8). The HLB value by the Griffin method shows a value in the range of 0 to 20, and the larger the value, the more hydrophilic the compound is.
HLB value = 20 x (mass% of hydrophilic groups) = 20 x (sum of formulas of hydrophilic groups / molecular weight of surfactant) ... (8)

Specific examples of the polyalkylene oxide adduct of the aliphatic alcohol represented by the formula (6) include a polyethylene oxide adduct of an aliphatic monohydric alcohol having 9 to 11 carbon atoms, trade name: Sannonic DE-70 (HLB value). : 13.2), ID-60 (HLB value: 12.5), ID-70 (HLB value 13.2), and the above can be mentioned by Sanyo Kasei Co., Ltd. Further, as a polyoxyethylene oxide polypropylene adduct adduct of isodecyl alcohol, trade name: Neugen LF-80X (HLB value: 13.9), manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. can also be mentioned.
The polyalkylene oxide adduct of the aliphatic alcohol represented by the formula (7), wherein the aliphatic alcohol is an aliphatic polyhydric alcohol, is, for example, composed of polyethylene oxide and acetylene glycol, trade name: Orphine E1010. (14 carbon atoms of acetylene glycol, HLB value: 13-14, manufactured by Nisshin Chemical Industry Co., Ltd.) and trade name: acetylenol E-100 (14 carbon atoms of acetylene glycol, HLB value 13-14, Kawaken Fine Chemicals) Co., Ltd.).
The polyalkylene oxide adduct of the aliphatic alcohol used in the present invention is not limited to these.

The content of the polyalkylene oxide adduct of the aliphatic alcohol in the present invention is preferably 0.1% by mass to 10% by mass, and 0.2% by mass to 5% by mass, based on the total mass of the ink composition. It is more preferable to set it to%. Particularly preferably, it is 0.25% by mass to 2% by mass.
When the content of the polyalkylene oxide adduct of the aliphatic alcohol is within the above numerical range, the dryness of the brush stroke can be improved. Further, when writing on the ink-applied portion, it becomes easy to prevent the colorant in the ink-applied portion from being released into the handwriting.

In the ink composition of the present invention, the ratio of the total mass of the MQ resin to the total mass of the polyalkylene oxide adduct of the aliphatic alcohol is preferably 0.3 to 25, preferably 0.4 to 20. It is more preferably 0.5 to 10 and even more preferably 0.5 to 10. Within the above range, the handwriting drying property can be improved.

In addition, the ink composition of the present invention may contain various additives such as a pH adjuster, a rust preventive, a preservative, and a chelating agent for the purpose of improving the physical characteristics and functions of the ink.

Examples of the pH adjuster include basic inorganic compounds such as ammonia, sodium carbonate, sodium phosphate and sodium hydroxide, basic organic compounds such as sodium acetate, triethanolamine and diethanolamine, lactic acid, acetic acid and citric acid. ..

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

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

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

Further, in the present invention, a moisturizer other than the water-soluble organic solvent may be further contained. For example, N, N, N-trialkyl amino acids such as urea, sorbitol, dextrin, and trimethylglycine, hyaluronic acids, and the like can be preferably used.

Further, a nonionic surfactant, an anionic surfactant, a cationic surfactant, a surfactant having an acetylene bond in the structure, a fluorine-based surfactant and the like can be added.
Since these improve the wettability to the ink storage body and the ink flow rate adjusting body, good handwriting can be obtained by smooth ink ejection.
It is also possible to add an antifoaming agent. Further, a lubricant such as a phosphoric acid ester-based surfactant or a fatty acid can also be added.
Further, in the present invention, a shear thinning agent can be added to impart appropriate viscosity to the ink for practical use. The shear thinning agent used can be appropriately selected from conventionally known agents. Specific examples thereof include polysaccharides such as xanthan gum, succinoglycan and carrageenan, synthetic polymer nonionic surfactants such as polyacrylic acid, crosslinked polyacrylic acid and associative urethane, and anionic surfactants. It can be used as one kind or a mixture of two or more kinds.

The pH value of the ink composition according to the present invention is preferably 10 or less. When the pH value is 10 or less, it is possible to obtain a handwriting having excellent color clarity while sufficiently obtaining the water resistance imparting effect of the MQ resin, and further to obtain excellent stability over time.
Further, when the colored resin particles are used, the pH value is preferably less than 7, because discoloration and aggregation of the colored resin particles can be easily suppressed. Further, when the fluorescent colored resin particles are used in the present invention, it is particularly preferable that the pH value is 6.5 or less because the above effect can be remarkably obtained.
Furthermore, in addition to improving handwriting water resistance, writing performance, and stability over time in a well-balanced manner, the pH value is more preferably 3.0 to 6.5, and is 4.0 to 6.5, considering the safety of ink. It is more preferable that there is, and particularly preferably 5.0 to 6.3.
In the present invention, the pH value can be measured at 20 ° C. by, for example, a D-51 type pH meter (manufactured by HORIBA, Ltd.).

The viscosity of the ink composition according to the present invention can be set to an appropriate viscosity for the writing instrument used, but when the ink composition of the present invention is used for a marking pen, the viscosity is 1 mPa · s to 20 mPa. The ink composition of the present invention preferably contains MQ resin, preferably 2 mPa · s to 10 mPa · s, even for low-viscosity inks having a viscosity range as described above. It is easily adjustable.
When the viscosity of the ink composition is within the above numerical range, the ink ejection property when used for a marking pen can be appropriately improved, so that the ink composition is excellent in color development, but is good without blurring or hollowing out. You can get a handwriting. Further, it becomes easy to improve the handwriting drying property, and it becomes easy to suppress the strike-through of the paper surface.
The viscosity of the ink composition can be measured using a B-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd., using a BL adapter) under the conditions of 20 ° C. and a rotation speed of 30 rpm.

The surface tension of the ink composition is preferably 25 mN / m to 45 mN / m in an environment of 20 ° C. When the surface tension is within the above numerical range, it is possible to improve the paper surface permeability of the ink composition, easily suppress the bleeding of the handwriting and the strike-through to the paper surface, and improve the water resistance of the handwriting. it can. Further, the writing performance can be improved by improving the wettability of the ink composition and suppressing the occurrence of blurring and hollowing out in the handwriting. The surface tension of the ink composition is preferably 30 mN / m to 40 mN / m in consideration of handwriting drying property and writing performance.
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.

<Manufacturing method of ink composition>
The ink composition according to the present invention can be produced by any conventionally known method. Specifically, the required amounts of each of the above components are blended and mixed with various stirrs such as a magnet hot stirrer, a propeller stirrer, a homogenizer stirrer, a homodisper, a homomixer, a planetary stirrer, and various dispersers such as a bead mill. , Can be manufactured.

<Writing instruments>
The structure and shape of the writing tool itself for filling the water-based ink composition for writing tools of the present invention are not particularly limited, and conventional general-purpose ones can be applied, such as fiber chips, felt chips, porous chips, and plastic chips. It can be used for various writing tools such as a marking pen (sign pen) with a pen core as a pen tip, a ball pen with a ball pen tip as a pen tip, and a perennial brush with a metal pen tip.

As the material of the pen tip of the writing tool, for ballpoint pens and fountain pens, metals such as superhard alloys, stainless steel and gold, and ceramics such as silicon carbide can be exemplified, and for marking pens (sign-tip pens), polyester, nylon, polyurethane, polyethylene and polypropylene can be exemplified. , Synthetic resin such as acrylic can be exemplified.

The ink composition of the present invention containing MQ resin is particularly preferably used for a marking pen (sign pen). Since marking pens are likely to be used to mark important points, it is a problem that their handwriting is smeared, thinned, or lost due to water droplets or the like. Therefore, the ink composition of the present invention having excellent handwriting water resistance can be effectively used for a marking pen. Furthermore, since the marking pen using the fluorescent ink is more likely to be used as described above, excellent water resistance is particularly required. Therefore, in the present invention, it is particularly effective to use fluorescent colored resin particles to prepare fluorescent ink and use it for a marking pen.
When used for a marking pen, the pen tip may be a pen core such as a fiber tip, a felt tip, a porous tip, or a plastic tip as described above. Among them, a fiber bundle is bound with a resin. It is preferable to use a pen core of a fiber tip or a porous tip obtained by fusing resin particles such as polypropylene. The shape of the pen core may be a cannonball type, a chisel type, a brush pen type, or the like.

The pen core contains voids composed of pores, but the pore diameter can be arbitrarily set as long as the pore diameter is such that the colorant can pass through, and the porosity is in the case of a fiber chip. Is preferably 55% to 75%, and in the case of a porous chip, it is preferably 30% to 50%. Considering the ejection property of the ink composition, the void ratio of the pen core is more preferably 60% to 70% in the case of a fiber chip, and 40% to 50% in the case of a porous chip. Is more preferable. When the porosity of the pen core is within the above numerical range, the pigment is not clogged and an appropriate ink ejection amount can be maintained.

Further, the writing instrument on which the ink composition of the present invention can be used may have a structure in which the ink composition is directly filled, and an ink container or an ink occlusion capable of filling the ink composition. It may have a body. Further, the ink container or the ink storage body may be an ink cartridge type writing instrument and a converter type writing instrument having a structure that can be detachably replaced with the writing instrument main body.
Further, in a writing instrument having a structure in which the ink composition is directly filled or a writing instrument provided with an ink container, when a pigment is used as a colorant of the ink composition, the ink container is used to redistribute the pigment. It is preferable to incorporate a stirrer such as a stirrer ball for stirring the ink. Examples of the shape of the stirrer include a spherical body and a rod-shaped body. The material of the agitator is not particularly limited, and specific examples thereof include metal, ceramic, resin, and glass.
Further, when the ink storage body is provided with an ink storage body capable of filling the ink composition, the ink storage body is preferably a fiber bundle made of twisted fibers.

Like the pen core, the fiber focusing body contains voids composed of pores, and the pore diameter thereof can be arbitrarily set as long as the pore diameter is such that the colorant can pass through. On the other hand, the porosity of the fiber bundle is preferably 85% to 95%, more preferably 87% to 92%, in consideration of the ink supply property to the pen tip.

The ink supply mechanism is also not particularly limited. For example, (1) a mechanism provided with an ink guide core made of a fiber bundle or the like as an ink flow rate adjusting member and supplying an ink composition to a pen tip, (2). A mechanism provided with a comb groove-shaped ink flow rate adjusting member, intervening the ink composition to be supplied to the pen tip, and (3) a mechanism provided with an ink flow rate adjusting member by a valve mechanism to supply the ink composition to the pen tip. , (4) A mechanism for directly supplying the ink composition to the pen tip from the ink container or the barrel provided with the pen tip can be mentioned.

Further, the ink composition of the present invention is also used for a cap-type writing instrument provided with a cap covering the pen tip, and a retractable writing instrument capable of accommodating the pen tip in a shaft cylinder such as a knock type, a rotary type, or a slide type. Can be done.

The writing tool accommodating the ink composition of the present invention can be configured by appropriately selecting each member from the above-mentioned pen tip, ink filling mechanism, and ink supply mechanism, but can provide a stable ink ejection amount. Considering that it can be maintained, it is provided with a pen tip using the fiber tip or the porous tip and an ink filling mechanism using the fiber focusing body as the ink storage body, and the pen tip and the ink storage body are provided with the ink storage body. A filling type marking pen is preferably connected so that the ink composition stored in the body can be supplied to the pen tip.

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>
The following raw materials and each compounding amount were stirred and mixed at room temperature for 1 hour to obtain a water-based ink composition for writing instruments.
When the viscosity of the obtained ink composition was measured with a B-type rotational viscometer (using a BL adapter, manufactured by Tokyo Keiki Co., Ltd.), the viscosity at a rotation speed of 30 rpm at 20 ° C. was 3.5 mPa · s.
Further, as a result of measuring the pH of the ink composition at 20 ° C. using a pH meter (trade name: D-51, manufactured by Horiba Seisakusho Co., Ltd.), the pH value was 5.9.

・ Colorant 50.00% by mass
(30% by mass aqueous dispersion of fluorescent colored resin particles (fluorescent yellow))
-MQ resin (1) 8.62% by mass
(MQ resin emulsion (nonvolatile content 58% by mass, nonionic, low viscosity silicone oil contained, manufactured by Shin-Etsu Chemical Co., Ltd.)
・ Water-soluble organic solvent 10.00% by mass
(Glycerin)
・ Preservative 0.10% by mass
(4-Chloro-3-methylphenol)
・ Water 31.28% by mass

<Examples 2 to 15, Comparative Examples 1 to 3>
Examples 2 to 15 and Comparative Examples 1 to 3 are the same as those of Example 1 except that the types and blending amounts of the components contained in the ink composition are changed to the compositions shown in Tables 1 and 2. A water-based ink composition for writing instruments was obtained in the same manner.
The viscosity and pH value of each ink composition were also measured by the same method as in Example 1. However, since the viscosity of the ink composition of Comparative Example 2 exceeded the upper limit of measurement in the method of Example 1, a B-type rotational viscometer (using a BL adapter, manufactured by Tokyo Keiki Co., Ltd.) was used at 20 ° C. The measurement was performed under the condition of a rotation speed of 12 rpm.

The details of the materials used in the above examples are as follows. The explanation will be given according to the note numbers in the table.

(1) 30% by mass aqueous dispersion of fluorescent colored resin particles (fluorescent yellow), average particle diameter: 0.1 μm, trade name: SF-5015, manufactured by Shinroihi Co., Ltd. (2) Fluorescent colored resin particles (fluorescence) 37% by mass aqueous dispersion of pink), fluorescent colored resin particles [styrene-acrylonitrile resin particles colored with fluorescent dye], average particle size: 0.1 μm, trade name: Lumicol NKW-3207E, Nippon Fluorescent Chemicals (Pink) (3) Aqueous dispersion of 35% by mass of polymer dye, polymer dye [Partially sulfonated linear polyester resin (molecular weight: 18,000, hydroxyl value: 4-8, acid value: <5, Tg: 65 ° C., sulfonic acid equivalent: 400-600] and fluorescent dye (Flavin CI49005) in water at a mass ratio of 1: 0.26]
(4) MQ resin emulsion, low-viscosity silicone oil content, non-volatile content 58% by mass, nonionic property, MQ resin [M unit / Q unit (molar ratio) = 0.5 to 1.5, in formula (1) R is a methyl group), poly (oxyethylene) = alkyl (12 to 15 carbon atoms) ether contained, average particle size 0.49 μm, trade name: X-52-8005, manufactured by Shin-Etsu Chemical Industry Co., Ltd. (5) MQ Resin emulsion, containing low-viscosity silicone oil, non-volatile content 60% by mass, anionic, MQ resin [M unit / Q unit (molar ratio) = 0.5 to 1.5, R in formula (1) is a methyl group ), Contains sodium sulfonic acid salt compound, contains sorbitan fatty acid ester, (MQ resin dissolved in low-viscosity silicone oil (kinematic viscosity 6 cSt) and emulsified and dispersed in water with an anionic surfactant, MQ resin content 20% by mass, low-viscosity silicone oil content 39% by mass), average particle size 1.42 μm, trade name: KM-9717, manufactured by Shin-Etsu Chemical Industry Co., Ltd. (6) Styrene / acrylic resin emulsion, non-volatile content 50 Mass%, trade name: Mobile VDM7410, manufactured by Nippon Synthetic Chemical Co., Ltd.
(7) Polyethylene oxide polypropylene adduct adduct of isodecyl alcohol, HLB value: 13.9, trade name: Neugen LF-80X, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (8) Polyethylene oxide adduct of acetylene glycol, acetylene glycol Carbon number: 14, HLB value: 13-14, trade name: Orphine E1010, manufactured by Nissin Chemical Industry Co., Ltd. (9) 30 mass% aqueous solution of acetic acid
(10) Product name: Hokuside PCMC, manufactured by Hokuko Sangyo Co., Ltd. The above average particle size is measured using a laser diffraction type particle size distribution measuring machine (trade name "Nanotrack NANO-flex", Microtrack Bell Co., Ltd.). It is a particle diameter (D50) when the volume cumulative volume of the particle size distribution measured by the dynamic light scattering method is 50%.

<Test and evaluation>
2 g of the water-based ink composition for writing instruments of Examples 1 to 15 and Comparative Examples 1 to 3 was filled in an ink occlusion body of a marking pen provided with a pen tip, and the pen tip was impregnated with the ink composition. A marking pen was produced.
The marking pen uses a chisel-type polyester fiber tip [(outer dimensions: length 32 mm, diameter 4 mm), void ratio 60%] as the pen tip, and a fiber bundle made of twisted yarn as the ink occlusion body. [(Outer dimensions: length 77 mm, diameter 7.3 mm), void ratio 88%] was used to connect the pen tip and the ink occlusion body so that the ink composition stored in the ink occlusion body could be supplied. ..
The following tests and evaluations were carried out using the obtained marking pen as a writing instrument for testing.

<Handwriting water resistance test>
Using a test writing instrument using the ink compositions of Examples 1 to 15 and Comparative Examples 1 to 3, write 3 cm straight on test paper, leave it for 1 hour, and then test so that the handwriting is immersed. The handwriting state after immersing the paper in ion-exchanged water for 1 hour was visually observed, and the handwriting water resistance was evaluated according to the following evaluation criteria. As the test paper, a writing paper conforming to JIS P3201 was used.
◎ ◎: No bleeding of handwriting or decrease in density was observed.
⊚: The outflow of the colorant occurred very slightly, and the immersion liquid was slightly colored, but the bleeding of the brush stroke and the decrease in the concentration were very slight, and there was no problem in practical use.
◯: A slight outflow of the colorant occurred and the immersion liquid was slightly colored, but the bleeding of the handwriting and the decrease in the concentration were very slight, and there was no problem in practical use.
Δ: The colorant flowed out, the immersion liquid was colored, and bleeding of handwriting and a decrease in concentration were remarkably observed, which was a level of concern in practical use.
X: The handwriting disappeared and could not be visually recognized.

<Writing performance test (handwriting color development)>
Using a test writing instrument using the ink compositions of Examples 1 to 15 and Comparative Examples 1 to 3, straight-line writing was performed on the test paper, and the color development of the obtained handwriting was visually observed. The writing performance (handwriting color development) was evaluated according to the evaluation criteria of. As the test paper, a writing paper conforming to JIS P3201 was used.
◯: The color is clear.
Δ: The color is slightly unclear, but it is sufficiently visible.
X: The color is unclear and difficult to see, which is a problem in practical use.

<Writing performance test (writing ability)>
Using a test writing instrument using the ink compositions of Examples 1 to 15 and Comparative Examples 1 to 3, straight-line writing was performed on the test paper, and the state of the obtained handwriting was visually observed and described below. The writing performance (writing ability) was evaluated according to the evaluation criteria. As the test paper, a writing paper conforming to JIS P3201 was used.
◯: No blurring or hollowing out was found in the handwriting.
Δ: Slight blurring and hollowing out were confirmed in the handwriting.
X: There was marked blurring or hollowing out in the handwriting, or writing was not possible.

<Handwriting drying test>
When straight-line writing was performed on the test paper using the test writing instruments using the ink compositions of Examples 1 to 15 and Comparative Examples 1 to 3, and the handwriting was rubbed with a finger 3 seconds after writing. The spread of the ink composition to the periphery was visually observed, and the handwriting dryness was evaluated according to the following evaluation criteria. As the test paper, a writing paper conforming to JIS P3201 was used.
⊚: No evidence of ink spreading around the handwriting is confirmed.
◯: There is evidence that the ink has spread slightly around the handwriting, but the degree of spread is slight.
Δ: Evidence of ink spreading around the handwriting is confirmed, but there is no problem in practical use.
X: The spread of ink around the handwriting is remarkable.
The handwriting drying properties when the ink compositions of Examples 1 to 8, 14 and 15 were used were all 0 in the above evaluation, but those when the ink compositions of Examples 14 and 15 were used. However, as compared with the case where the ink compositions of Examples 1 to 8 were used, the degree of spread of the ink was smaller and the handwriting drying property was more excellent.

The ink compositions of Examples 1 to 15 were all good in handwriting water resistance, writing performance (handwriting color development), and writing performance (writing property).
In addition, the ink compositions of Examples 1 to 15 did not cause discoloration, and handwriting could be obtained with a desired color.

Further, the ink compositions of Examples 9 to 13 are superior in handwriting drying property to the ink compositions of Examples 1 to 8, and have excellent handwriting water resistance, writing performance (handwriting color development), and writing. It has been found to be particularly effective as a water-based ink composition for writing instruments and further as an ink composition for marking pens because it is excellent in performance (writing property) but also in handwriting drying property. It was.

On the other hand, since the ink compositions of Comparative Examples 1 to 3 do not use MQ resin, the ink composition can satisfy all of handwriting water resistance, writing performance (handwriting color development), and writing performance (writing property). There wasn't.
In the ink composition of Comparative Example 2, the colorant aggregated immediately after the ink was adjusted, causing poor follow-up to the pen tip, making writing impossible, and no handwriting was obtained. Therefore, the handwriting water resistance test, the writing performance test (handwriting color development), and the handwriting drying property test were not performed.

Based on the above, the water-based ink composition for writing instruments containing MQ resin, colorant, and water produces handwriting even if water droplets adhere to the obtained handwriting or if it is immersed in water. It has excellent handwriting water resistance without bleeding, thinning, or disappearing, and also has excellent writing performance such as obtaining a handwriting with the desired color and excellent color clarity without blurring or hollowing out. Furthermore, it was found that the writing instrument using the water-based ink composition for writing instruments is also excellent as a writing instrument.

The ink composition of the present invention can be used for various writing instruments such as ballpoint pens, marking pens, perennial pens, brush pens, and pen for calligraphy, and the writing instrument containing the ink composition has water resistance and color clarity. Furthermore, it is excellent as a writing instrument because it can bring about a good handwriting without blurring or hollowing out.

Claims (5)

A water-based ink composition for writing instruments, which comprises a colorant, an MQ resin, and water. The water-based ink composition for writing instruments according to claim 1, wherein the content of the MQ resin is 0.01% by mass to 30% by mass based on the total mass of the water-based ink composition for writing instruments. The water-based ink composition for writing tools according to claim 1 or 2, further comprising a polyalkylene oxide adduct of an aliphatic alcohol. A writing instrument comprising the water-based ink composition for a writing instrument according to any one of claims 1 to 3. The writing instrument according to claim 4, which is a marking pen.