JP2022100837A - Water-based ink composition for writing instruments, and writing instrument including the same - Google Patents

Abstract

To provide a water-based ink composition for writing instruments that can form handwritten characters and the like that are transparent and glossy, and three-dimensional.SOLUTION: A water-based ink composition for writing instruments contains a film-forming polymer with a lowest film-forming temperature of 50°C or lower, an associative thickener, a colorant, and water. The ink composition has a viscosity of 50 mPa s or more at 20°C and a shear rate of 1.92 sec-1.SELECTED DRAWING: None

Description

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

When writing with a writing instrument filled with an ink composition, the ink usually penetrates the paper surface and a flat handwriting is obtained. By making this handwriting three-dimensional, you can enjoy different handwriting and decorate it with various materials. In addition, since three-dimensional handwriting can be identified by touching it, it is also in demand as a social product.

As one of the methods for forming a three-dimensional handwriting, a water-based ink composition containing a large amount of a three-dimensional film-forming component has been proposed (for example, Patent Document 1). There is a demand for a water-based ink composition that can obtain a three-dimensional handwriting that is more excellent in strength and more stable.

Japanese Unexamined Patent Publication No. 2005-8873

The present invention solves the above-mentioned problems and provides a water-based ink composition for stationery that is transparent, glossy, and can form a three-dimensional handwriting.

The water-based ink composition for writing tools according to the present invention comprises a film-forming polymer having a minimum film-forming temperature of 50 ° C. or lower, an associated thickener, a colorant, and water.
The viscosity of the ink composition is 50 mPa · s or more under the conditions of 20 ° C. and a shear rate of 1.92 sec ^-1 .

The writing tool according to the present invention contains the above-mentioned water-based ink composition for writing tools.

According to the present invention, there is provided a water-based ink composition for writing tools that is transparent, glossy, and capable of forming a three-dimensional handwriting. The obtained handwriting has low surface adhesiveness and excellent stability, less cracking, and excellent strength.

It is a vertical sectional view of an example of a cap type pressure ballpoint pen. It is a vertical sectional view of the ballpoint pen of FIG. 1 with a cap removed. It is explanatory drawing which shows the writing tool in a state (pressurized state) in which a cap is fitted to the rear end portion of a shaft cylinder.

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

<Aqueous ink composition for writing tools>
The water-based ink composition for writing tools according to the present invention (hereinafter, may be referred to as an ink composition) includes a film-forming polymer having a minimum film-forming temperature of 50 ° C. or less, an associative thickener, a colorant, and water. Contains.
The viscosity of the ink composition is 50 mPa · s or more, preferably 100 mPa · s or more, more preferably 500 mPa · s or more under the conditions of 20 ° C. and a shear rate of 1.92 sec ^-1 (0.5 rpm). It is more preferably 1000 mPa · s or more, 2000 mPa · s or more, more preferably 3000 mPa · s or more, and preferably 10000 mPa · s or less, and more preferably 8000 mPa · s or less. be. When the viscosity is within the above numerical range, stable ink ejection from the pen tip is excellent, and a sufficiently three-dimensional handwriting can be obtained.
The solid content ratio of the ink composition is preferably 10 to 50% by mass, more preferably 15 to 30% by mass, based on the total mass of the ink composition. When the solid content ratio is within the above numerical range, it is easy to set the ink viscosity under the conditions of 20 ° C. and a shear rate of 1.92 sec ^-1 to 50 mPa · s or more, and it is possible to form a handwriting having an excellent three-dimensional effect. In addition, the three-dimensional effect of the handwriting can be maintained even after the ink has dried.

The ink composition according to the present invention preferably has a higher viscosity and solid content ratio than the commonly used ink composition for writing tools as described above, in order to enable the formation of three-dimensional handwriting.

The ink composition according to the present invention is used for writing tools, but a preferred embodiment of the present invention is a ballpoint pen. When the ballpoint pen contains the ink composition according to the present invention, it is preferable that good ink ejection property can be obtained at the time of writing.
Therefore, the viscosity of the ink composition is preferably 500 mPa · s or less, more preferably 200 mPa · s or less, and more preferably 150 mPa · s under the conditions of 20 ° C. and a shear rate of 192 sec ^-1 (50 rpm). It is less than or equal to, more preferably 120 mPa · s or less, more preferably 110 mPa · s or less, and even more preferably 100 mPa · s or less.
Further, considering that it is possible to form a three-dimensional handwriting but to obtain better ink ejection performance than the pen tip of a ballpoint pen, the viscosity of the ink composition at rest and the viscosity gradient at the time of flow must be at least a certain level. That is, it is preferable that the viscosity ratio of the ink composition at the time of high shear and the time of low shear is at least a certain level.
Therefore, the viscosity ratio of the ink composition at the time of high shear and low shear (viscosity under the condition of 20 ° C. and shear rate of 1.92 sec ^-1 / viscosity under the condition of 20 ° C. shear rate of 192 sec ^-1 ) is preferable. It is 10 or more, more preferably 20 or more, still more preferably 40 or more, still more preferably 45 or more, still preferably 100 or less, and even more preferably 80 or less.
Further, when the ink composition of the present invention is used as an ink composition for a ballpoint pen, considering that good ink ejection properties can be obtained from the beginning of writing and a three-dimensional brush stroke can be obtained, the viscosity ratio of the ink composition ( Viscosity under the conditions of 20 ° C. and a shear rate of 1.92 sec ^-1 / 20 ° C. and viscosity under the conditions of a shear rate of 19.2 sec ^-1 ) are preferably 1.5 or more, more preferably 3.0. It is more preferably 5.0 or more, more preferably 5.5 or more, preferably 20 or less, and more preferably 10 or less.

[Membrane-forming polymer]
The ink composition according to the present invention comprises a film-forming polymer having a minimum film-forming temperature of 50 ° C. or lower (hereinafter, may be referred to as a film-forming polymer).
The film-forming polymer used in the present invention is uniformly dispersed in the ink composition, and is preferably emulsified and dispersed in an aqueous medium. Specifically, the film-forming polymer used in the present invention exists in the form of particles without being dissolved in the ink composition, and at the time of writing, water evaporates and the particles bind to each other to form a film. ..

The minimum film-forming temperature (hereinafter, may be referred to as MFT) is the minimum temperature at which the film-forming polymer forms a smooth and transparent continuous coating film. MFT can be measured according to JIS K6828-2 (2003).
The MFT of the film-forming polymer used in the present invention is preferably 40 ° C. or lower. Further, considering the suppression of the occurrence of cracks in the obtained handwriting, the temperature is more preferably 30 ° C. or lower, and further preferably 0 ° C. or lower.

Examples of the film-forming polymer include acrylic resin, urethane resin, vinyl resin, and styrene resin. Among them, an acrylic resin or a urethane resin is preferable because it has good compatibility with an association type thickener described later, particularly a urethane-based association type thickener, and an ink thickening effect can be easily obtained. Acrylic resin is more preferable, and acrylic resin or styrene acrylic resin is more preferable, because the dispersion stability of the above can be improved and a three-dimensional brush stroke can be stably formed.
The film-forming polymer may be a combination of two or more.

The mass average molecular weight of the film-forming polymer is preferably 10,000 to 10 million, more preferably 30,000 to 3 million, and even more preferably 100,000 to 1 million. Here, in the present invention, the mass average molecular weight can be measured by a usual method using gel permeation chromatography. The same applies to the subsequent mass average molecular weights.

In producing the ink composition according to the present invention, the film-forming polymer may be added in the form of a dispersion dispersed in water (using a dispersant if necessary), for example, an emulsion. It is also a preferred form that the film-forming polymer is added to the ink composition in the form of an emulsion.

Examples of commercially available emulsions containing film-forming polymers include "Jonclyl JDX-7741", "Jonclyl PDX-7734", "Jonclyl PDX-7787", "Jonclyl PDX-7615", "Jonclyl PDX-7775", "Jonclyl PDX-7775". Jonclyl PDX-7630A, "Jonclyl PDX-7356", "Jonclyl PDX-7777", "Jonclyl PDX-7430", "Jonclyl PDX-7326", "Jonclyl PDX-7626", "Jonclyl PDX-7616A", "Jonclyl PDX-7616A" PDX-7356, "Jonclyl PDX-7692", "Jonclyl 352D", "Jonclyl PDX-7667", "Jonclyl PDX-7700", "Jonclyl PDX-7696" (BASF), "NeoCryl XK-1" "XK-12", "NeoClyl XK-16", "NeoClyl XK-30", "NeoClyl XK-36", "NeoClyl XK-188", "NeoClyl XK-240", "NeoClyl A-2092", "NeoCryl A-2092" -62 ”,“ NeoCryl BT-20 ”,“ NeoCryl A-614 ”,“ NeoCryl A-633 ”,“ NeoCryl A-655 ”,“ NeoCryl A-1092 ”,“ NeoCryl A-1093 ”,“ NeoCryl A-1093 ” 1094 ”,“ NeoCryl A-1125 ”,“ NeoCryl A-1127 ”,“ NeoCryl A-6069 ”,“ NeoCryl A-6092 ”(Kusumoto Kasei Co., Ltd.),“ Movinyl LDM7582 ”(Nippon Synthetic Chemical Industry Co., Ltd.), "727", "743N", "745", "752", "801", "940", "1752", "6520", "6720", "7525", "7540", "7820", "8020" , "8030", "DM60", "DM772", "DM774", "LDM6740", "LDM7522", "LDM7523", "VDM7410", "ES-85", "109E", "172E", "760H" , "DS5", "180E", "761HG", "DC02", "18" 5EK ”,“ 987B ”,“ D025N ”,“ 711H ”,“ 128N ”,“ DLR1 ”,“ 138N ”,“ 168N ”, 135N”, “FK-900”, “BA-10L”, “BA-20” , "BA-53", "BA-58", "BA-321L", "BA-321H", "DM201P", "DM1645P", "LDM1646P", "D5100P", "DM2072P", "LDM2077P", "LDM7000P", "LDM7100P", "LDM7300P", "LDM7400P" (Japan Coating Resin Co., Ltd.), "Viniblanc 271", "Viniblanc 278", "Viniblanc 715S", "Viniblanc 735", "Viniblanc 603EM", "Viniblanc" 603HA, "Viniblanc 603SK", "Viniblanc 603VS" (Nisshin Chemical Industry Co., Ltd.) and the like can be mentioned.

The content of the film-forming polymer is preferably 1 to 50% by mass based on the total mass of the ink composition, more preferably 1 to 30% by mass, and further preferably 10 to 10 to 30% by mass in consideration of ejection properties. It is 30% by mass, more preferably 15 to 30% by mass, and most preferably 15 to 28% by mass. When the content of the film-forming polymer is in the range of the above numerical values, it is possible to form a handwriting having an excellent three-dimensional effect, in which the swelling of the handwriting can be sufficiently confirmed.
As the film-forming polymer, a plurality of types having different MFTs can be combined.

[Associative thickener]
The ink composition according to the present invention comprises an association type thickener. The associated thickener has a hydrophilic group as a skeleton and has a hydrophobic group at a side chain or a terminal. The associated thickener is stably present in the aqueous medium due to the interaction between the hydrophilic group and the aqueous medium, while one of the hydrophobic groups is associated with the film-forming polymer or the particles of the colorant. By adsorbing and further adsorbing the other hydrophobic group to the hydrophobic group of another molecule, the film-forming polymer, the particles of the colorant, etc., a weak crosslinked structure is formed, and the ink thickening effect can be obtained. ..

Examples of the associative thickener include urethane-based associative thickeners, polyacrylic acid-based associative thickeners, polyvinyl-based associative thickeners, polyether-based associative thickeners, and polyglycol-based associative thickeners. Thickeners, maleic anhydride copolymer-based thickeners, polyamide-based associative thickeners, polyester-based associative thickeners, hydrophobicized cellulose ester-based associative thickeners, and polycarboxylic acid-based associative thickeners. Thickeners can be mentioned. A urethane-based association type thickener is preferable from the viewpoint of improving the glossiness of the film.

The urethane-based associated thickener is an aqueous medium in which a urethane bond existing at the end of the thickener is associated with and adsorbed to a hydrophobic group of another molecule, a film-forming polymer, particles of a colorant, or the like. Further, it refers to a compound that thickens the ink composition by associating the ends of the thickener with each other. Examples of the urethane-associated thickener include a compound having a urethane bond and a polyether chain in the molecule, that is, a compound having a urethane structure and a polyether structure.

Examples of commercially available urethane-based associated thickeners include "Adecanol UH-756VF", "Adecanol UH-462", "Adecanol UH-420", "Adecanol UH-472", and "Adecanol UH-540". "Adecanol UH-814N" (ADEKA Co., Ltd.), "SN Sickner 660T", "SN Sickner 665T", "SN Sickner 612", "SN Sickner 612NC", "SN Sickener 6-1N", "SN Sickener 621N", "SN" "Sickener 621TF", "SN Sickner 623N", "SN Sickner 623N", "SN Sickner 625N", "Nopal 700N" (San Nopco Co., Ltd.), "Chixo Star" (Japan Material Technologies Corporation), "OPTIFLO T1000", "OPTIFLO" "L1400", "OPTIFLO M2600VF", "OPTIFLO H7500VF" (Big Chemie Japan Co., Ltd.) and the like can be mentioned.

When the ink composition of the present invention is used as an ink composition for a ballpoint pen, it is preferable to use an association-type thickener that imparts thixotropic viscosity among the association-type thickeners. This is because it is easy to set the viscosity ratio of the ink composition at the time of high shear and low shear within a desired range, and it is possible to form a handwriting with excellent three-dimensional effect while improving the ink ejection property from the pen tip. be.

The mass average molecular weight of the associated thickener is preferably 500 to 500,000, more preferably 800 to 300,000, still more preferably 1,000 to 100,000.

The content of the association type thickener is preferably 0.01 to 5% by mass, more preferably 0.05 to 1% by mass, and more preferably 0, based on the total mass of the ink composition. It is 0.05 to 0.8% by mass. When the content of the association-type thickener is in the range of the above numerical values, it is easy to bring about an appropriate viscosity to the ink composition, and it is possible to form a handwriting having an excellent three-dimensional effect in which the swelling of the handwriting can be sufficiently confirmed.
Further, in consideration of imparting sufficient viscosity to the ink composition and obtaining a stroke having an excellent three-dimensional effect, the mass ratio of the associated thickener to the film-forming polymer (associative thickener / film-forming polymer). ) Is preferably 0.001 to 0.2, more preferably 0.001 to 0.1, more preferably 0.001 to 0.05, and even more preferably 0.002 to 0. It is 0.03.

[Colorant]
The ink composition according to the present invention comprises a colorant. Any conventionally known pigment or dye can be used. Above all, the colorant is preferably a pigment because it is easy to obtain handwriting with good color development and excellent three-dimensional effect.

Examples of the pigment include inorganic, organic and processed pigments, and specific examples thereof include carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine pigment, azo pigment and quinacridone pigment. , Kinoftalone-based pigments, styrene-based pigments, triphenylmethane-based pigments, perinone-based pigments, perylene-based pigments, dioxazine-based pigments, and brilliant pigments, microcapsule pigments, colored resin pigments and the like. As the pigment, an aqueous dispersion pigment product or the like dispersed in a medium using a pigment dispersant such as a surfactant in advance may be used.

Further, among the pigments, it is preferable to use a colored resin pigment. As will be described later, since the colored resin pigment is colored with a colorant on the resin particles, the association-type thickener is easily associated and adsorbed, and the ink thickening effect is easily obtained. Therefore, it is easy to bring an appropriate viscosity to the ink composition, and it is possible to stably form a three-dimensional handwriting. Furthermore, by using a colored resin pigment, it is easy to maintain excellent handwriting transparency and gloss.
In the present invention, the colored resin particle pigment means that the resin particles are colored with a coloring agent. Here, the colorant is not particularly limited as long as it can color the resin particles, and any pigment or dye can be used. The resin particles have excellent alkali resistance, acid resistance, and heat resistance, are highly stable even in the presence of various additives, and are not easily affected by the thermal environment. Therefore, the styrene-acrylonitrile resin is used. It is preferably particles (hereinafter, may be referred to as SA resin particles).
Specific examples of commercially available products containing colored resin particles include Shin Loihi Color Series (manufactured by Shin Loihi Co., Ltd.), Lumicol Series (manufactured by Nippon Fluorescent Chemical Co., Ltd.), and LM Series (Fuji Dye Co., Ltd.). ), Epocolor series (manufactured by Nippon Shokubai Co., Ltd.). Specifically, examples of the Lumicall series include the same NKW-2317H, the same NKW-6307H, the same NKW-2308H, the same NKW-2302H, the same NKW-2305H, and the same NKW-6305H. The Shinrohi color series includes the Shinrohi color base SW-11, SW-12, SW-13, SW-14, SW15, SW-16, SW-17, SW-18, and the same. SW-27, SW-37, SW-47, SF-1012, SF-1013, SF-1014, SF-1015, SF-1017, SF-1027, SF-1038, SF- 5015 and the like can also be mentioned.

Examples of the dye include phthalocyanine dyes, pyrazolone dyes, niglosin dyes, anthraquinone dyes, azo dyes and the like.

The content of the colorant varies depending on the type, but is preferably 0.05 to 5% by mass, more preferably 0.1 to 1% by mass, based on the total mass of the ink composition.
The colorant may be used alone or in combination of two or more as appropriate.

[water]
The ink composition according to the present invention comprises 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.
The water content is preferably 10 to 90% by mass, more preferably 50 to 70% by mass, based on the total mass of the ink composition.

(Other additives)
The ink composition of the present invention requires the above-mentioned components (film-forming polymer, associated thickener, colorant and water), but may contain components other than the above as necessary.

[Water-soluble resin]
The ink composition according to the present invention may further contain a water-soluble resin. By containing the water-soluble resin, the three-dimensional shape after writing can be maintained.
The water-soluble resin may be any resin that can be dissolved in water, but acrylic resin, polyester resin, polyethylene oxide, and polyvinylpyrrolidone are preferably used to give a three-dimensional effect while maintaining the transparency and glossiness of the brush stroke. You can get an excellent handwriting.
As the content of the water-soluble resin increases, the three-dimensional shape of the handwriting tends to be maintained, but the adhesiveness of the surface of the handwriting tends to increase, and the viscosity ratio (shear rate 1.92sec ^-1 ) described above tends to increase. Viscosity under the condition of 192sec ^-1 (viscosity under the condition of shear rate)) tends to be low. In consideration of these, the content of the water-soluble resin is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total mass of the ink composition.
Further, considering that the three-dimensional maintenance of the handwriting and the suppression of the adhesiveness of the handwriting surface can be obtained in a well-balanced manner while improving the ink ejection property, the content of the water-soluble resin is preferably based on the content of the film-forming polymer. It is 0.5 to 30% by mass, more preferably 5 to 20% by mass.
The mass average molecular weight of the water-soluble resin is preferably 5,000 to 1,500,000, more preferably 10,000 to 1,000,000, still more preferably 20,000 to 150,000, and even more preferably 20,000 to 8. It is 10,000.

[Water-soluble organic solvent]
The ink composition according to the present invention may further contain a water-soluble organic solvent. Depending on the type of water-soluble organic solvent, the writing performance at the time of dry-up can be improved, the dispersion stability can also be improved, the handwriting drying property is improved, and the adhesiveness of the formed handwriting can be improved. Can be suppressed.
For example, (i) glycols such as ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, or glycerin, (ii) methanol, ethanol, 1-propanol, isopropanol, isobutanol, t-butanol, propanol 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, 3-methoxybutanol. , Or glycol ethers such as 3-methoxy-3-methylbutanol and the like. These can be used as one kind or a mixture of two or more kinds.
Considering the improvement of handwriting drying property, it is preferable to use one having a vapor pressure of 3 kPa or more at 20 ° C., and more preferably to use one having a vapor pressure of 4 kPa or more. Specific examples thereof include methanol, ethanol, isopropanol, ethylene glycol dimethyl ether, and propylene glycol dimethyl ether.

Considering that the writing performance and the handwriting drying property are improved in a well-balanced manner while maintaining the three-dimensional shape, the content of the water-soluble organic solvent is preferably 0.1 to 10 based on the total mass of the ink composition. It is by mass, more preferably 1 to 8% by mass.

Further, 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 nitrite, diisopropylammonium nitrite, 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 fluorosurfactant and the like can also 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.

<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 stirrers such as a magnet hot stirrer, a propeller stirrer, a homogenizer stirrer, a homodisper, a homomixer, and a planetary stirrer, and various dispersers such as a bead mill. , Can be manufactured.

<Stationery>
The writing instrument according to the present invention contains the above-mentioned ink composition. The structure and shape of the writing tool itself for filling the water-based ink composition according to the present invention are not particularly limited, and conventional general-purpose ones can be applied, but it is preferably used for a ballpoint pen having a ballpoint pen tip or the like as a pen tip. .. The ink composition according to the present invention is more preferably used for a pressurized ballpoint pen. This is because when the ink composition according to the present invention, which tends to have a high viscosity, is used for a pressurized ballpoint pen, the ejection property is improved and a handwriting having an excellent three-dimensional effect can be formed.
As a pressurized ballpoint pen, a pressurized ballpoint pen that encloses a pressurized gas in the ink container and presses the ink composition toward the tip tip side by the pressure of the pressurized gas, a knock operation, a cap attachment, and a brush at the time of writing. A knock-type pressurized ballpoint pen or pen tip that compresses the space existing on the rear end side of the ink composition by moving the pen tip due to pressure, and presses the ink composition toward the tip tip side by the pressure due to this compression. Examples thereof include a cap-type pressurized ballpoint pen provided with a cap covering the pen, a pen-pressure-pressurized ballpoint pen, and the like. Since the ink composition according to the present invention tends to have a high solid content ratio, a cap-type pressure ballpoint pen that can seal the pen tip is more preferable in consideration of dry-up resistance.

The pressure applied to the ink composition filled inside from the rear end side of the ink storage cylinder by pressurization is preferably larger than the atmospheric pressure, specifically, larger than the atmospheric pressure and 1.5 times. The following is preferable. More specifically, when the atmospheric pressure is 1000 hPa, it is preferably higher than 1000 hPa and 1500 hPa or less, and more preferably higher than 1000 hPa and 1200 hPa or less. As a result, it is possible to make the ink consumption suitable while suppressing ink leakage from the front end portion of the chip, and it is possible to improve the handwriting quality and the handwriting density, such as obtaining a sufficient three-dimensional effect.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

<Example 1>
A base ink is prepared by heating and stirring the following materials other than the association type thickener in the following blending amount with a magnetic stirrer at room temperature, and then the following association type addition is added to the prepared base ink. The thickener was added in the following blending amount and sufficiently mixed and stirred using a homogenizer stirrer until a uniform state was obtained to obtain the ink composition of Example 1.
-Acrylic resin A (acrylic emulsion" NeoCryl XK-190 "(Kusumoto Kasei Co., Ltd.), solid content 45% by mass, MFT <0 ° C.) 55 parts by mass-Urethane-based thickener A (associative thickener" Adecanol UH -756VF ", ADEKA Co., Ltd., solid content 32% by mass) 0.5 parts by mass, colored resin particles A (30% by mass aqueous dispersion of fluorescent colored resin particles (fluorescent yellow)," SF-5017 "(Shin Roihi stock) Company)) 2 parts by mass, triethanolamine 0.5 parts by mass, 42 parts by mass of water

<Examples 2 to 11 and Comparative Examples 1 to 3>
Examples 2 to 11 and Comparative Examples 1 to 3 are water-based ink compositions in the same manner as in Example 1 except that the types and blending amounts of the components contained in the ink composition are changed to the compositions shown in Table 1. Got Numerical values of composition in the table indicate parts by mass.

表中、
・アクリル樹脂Ａ：アクリルエマルジョン「ＮｅｏＣｒｙｌ ＸＫ－１９０」（楠本化成株式会社）、固形分４５質量％、ＭＦＴ＜０℃、
・アクリル樹脂Ｂ：アクリルエマルジョン「Ｊｏｎｃｒｙｌ ＰＤＸ－７４３０」（ＢＡＳＦジャパン株式会社）、固形分３８質量％、ＭＦＴ４４℃、
・アクリル樹脂Ｃ：アクリルエマルジョン「モビニールＬＤＭ７５８２」（日本合成化学工業株式会社）、固形分４６質量％、ＭＦＴ２０℃、
・アクリル樹脂Ｄ：アクリルエマルジョン「ＮｅｏＣｒｙｌ Ａ－５５０」（楠本化成株式会社）、固形分４０質量％、ＭＦＴ＞１００℃、
・スチレンアクリル樹脂Ａ：アクリルエマルジョン「ＮｅｏＣｒｙｌ ＢＴ－６２」（楠本化成株式会社）、固形分４０質量％、ＭＦＴ１０℃、
・スチレンアクリル樹脂Ｂ：アクリルエマルジョン「ＮｅｏＣｒｙｌ Ａ－６６２」（楠本化成株式会社）、固形分４０質量％、ＭＦＴ＞９０℃、
・ウレタン系増粘剤Ａ：会合型増粘剤「アデカノール ＵＨ－７５６ＶＦ」（株式会社ＡＤＥＫＡ）、固形分３２質量％、
・ウレタン系増粘剤Ｂ：会合型増粘剤「ＳＮシックナー ６６５Ｔ」（サンノプコ株式会社）、固形分３０質量％、チクソトロピック性
・ウレタン系増粘剤Ｃ：会合型増粘剤「ＳＮシックナー ６６０Ｔ」（サンノプコ株式会社）、固形分２０質量％、チクソトロピック性
・ウレタン系増粘剤Ｄ：会合型増粘剤「アデカノール ＵＨ－４６２」（株式会社ＡＤＥＫＡ）、固形分３０質量％、
・アクリル系増粘剤Ａ：高分子型増粘剤「ＳＮシックナー ６１８」（サンノプコ株式会社）、固形分１３質量％、
・着色樹脂粒子Ａ：蛍光性着色樹脂粒子（蛍光ピンク）の３０質量％水分散体、「ＳＦ－５０１７」（シンロイヒ株式会社）、
・着色樹脂粒子Ｂ：蛍光性着色樹脂粒子（蛍光ピンク）の４４質量％水分散体、「ルミコールＮＫＷ－２３１７Ｈ」（日本蛍光化学株式会社）
・水溶性アクリル樹脂：アクリル樹脂含有水溶液「Ｊｏｎｃｒｙｌ ＰＤＸ６１２４」（ＢＡＳＦジャパン株式会社）、固形分２４．５質量％、
・ポリエチレンオキサイド：「アルコックスＬ－１１」（明成化学工業株式会社）、分子量約１１万、
・ポリエステル樹脂：「プラスコート Ｚ－５６１」、２５質量％水溶液。

In the table,
Acrylic resin A: Acrylic emulsion "NeoClyl XK-190" (Kusumoto Kasei Co., Ltd.), solid content 45% by mass, MFT <0 ° C,
-Acrylic resin B: Acrylic emulsion "Joncryl PDX-7430" (BASF Japan Ltd.), solid content 38% by mass, MFT44 ° C.,
-Acrylic resin C: Acrylic emulsion "Mobile LDM7582" (Nippon Synthetic Chem Industry Co., Ltd.), solid content 46% by mass, MFT 20 ° C,
Acrylic resin D: Acrylic emulsion "NeoCyl A-550" (Kusumoto Kasei Co., Ltd.), solid content 40% by mass, MFT> 100 ° C,
-Styrene acrylic resin A: Acrylic emulsion "NeoCryl BT-62" (Kusumoto Kasei Co., Ltd.), solid content 40% by mass, MFT 10 ° C,
-Styrene acrylic resin B: Acrylic emulsion "NeoCyl A-662" (Kusumoto Kasei Co., Ltd.), solid content 40% by mass, MFT> 90 ° C,
-Urethane-based thickener A: Association-type thickener "ADEKANOL UH-756VF" (ADEKA Corporation), solid content 32% by mass,
-Urethane-based thickener B: Association-type thickener "SN Thickener 665T" (San Nopco Ltd.), solid content 30% by mass, thixotropic property-Urethane-based thickener C: Association-type thickener "SN Thickener 660T" (San Nopco Ltd.), solid content 20% by mass, thixotropic / urethane-based thickener D: associated type thickener "Adecanol UH-462" (ADEKA Co., Ltd.), solid content 30% by mass,
-Acrylic thickener A: Polymer thickener "SN Thickener 618" (San Nopco Ltd.), solid content 13% by mass,
-Colored resin particles A: 30% by mass aqueous dispersion of fluorescent colored resin particles (fluorescent pink), "SF-5017" (Shin Roihi Co., Ltd.),
-Colored resin particles B: 44% by mass aqueous dispersion of fluorescent colored resin particles (fluorescent pink), "Lumicol NKW-2317H" (Nippon Fluorescent Chemical Co., Ltd.)
-Water-soluble acrylic resin: Aqueous solution containing acrylic resin "Joncryl PDX6124" (BASF Japan Ltd.), solid content 24.5% by mass,
-Polyethylene oxide: "Alcox L-11" (Meisei Chemical Works, Ltd.), molecular weight of about 110,000,
-Polyester resin: "Plus Coat Z-561", 25% by mass aqueous solution.

[viscosity]
The viscosity of the obtained ink composition was measured by an E-type rotational viscometer (model: DV-II + Pro, rotor: CPE-42, manufactured by Brookfield) at a shear rate of 1.92 sec ^-1 (rotation speed) in a 20 ° C environment. The ink viscosity was measured under the condition of 0.5 rpm). The results obtained are shown in Table 1.

[Viscosity ratio]
The viscosity of the obtained ink composition was measured by an E-type rotational viscometer (model: DV-II + Pro, rotor: CPE-42, manufactured by Brookfield) under a 20 ° C environment with a shear rate of 192 sec ^-1 (rotation speed 50 rpm). The ink viscosity was measured under the conditions. In Examples 3, 4, 8 and 10, the measurement limit of 128 mPa · s was exceeded, so that the measurement could not be performed.
The viscosity at the above shear rate of 1.92 sec ^-1 (0.5 rpm) and the viscosity at the shear rate of 192 sec ^-1 (50 rpm) were calculated, and the viscosity ratio (0.5 rpm / 50 rpm) was obtained. The results obtained are shown in Table 1.

In addition, the viscosity of the obtained ink composition was measured by an E-type rotational viscometer (model: DV-II + Pro, rotor: CPE-42, manufactured by Brookfield) in a 20 ° C environment with a shear rate of 19.2 sec ^-1 (rotation). The ink viscosity was measured under the condition of several 5 rpm).
The viscosity at the above shear rate of 1.92 sec ^-1 (0.5 rpm) and the viscosity at the shear rate of 19.2 sec ^-1 (5 rpm) were calculated, and the viscosity ratio (0.5 rpm / 5 rpm) was obtained. Example 1 Was 5.9, Example 2 was 8.1, Example 3 was 3.9, Example 4 was 2.8, Example 5 was 4.5, and Example 10 was 1.0.

The ink compositions of Examples and Comparative Examples were filled in a ballpoint pen refill 7 of a cap-type pressurized ballpoint pen 1, and the ink ejection property in a state where pressure was applied was confirmed. When the ink composition of Example 10 was used, the ink could not be ejected. Therefore, in the subsequent handwriting evaluation, the ink composition was written using a decoration pen. Other ink compositions can be written with the above-mentioned pressure ballpoint pen, and in the subsequent handwriting evaluation, the above-mentioned pressure ballpoint pen was used for writing. Regarding the ink compositions of Examples, the ink compositions of Examples 1, 2, 6 and 7 had the best ejection properties, followed by Examples 3, 5, 8, 9 and 11. ..

1 to 3 show a cap type pressure ballpoint pen 1. In the cap-type pressurized ballpoint pen 1, the ballpoint pen refill 7 is arranged in a shaft cylinder main body in which a front shaft 2 having a grip member 14 mounted on a grip portion and a rear shaft 3 are connected.
Further, in the cap type pressure ballpoint pen 1, the translucent cap 4 obtained by injection molding a PP resin is formed on the inner wall of the cap 4 on the fitting convex portion formed on the side wall of the front shaft 2. It is detachably attached by passing over the fitting protrusion and fitting. When the cap is attached to the front shaft 2, the ballpoint pen tip 10 is sealed by the sealing member provided in the cap.

A ballpoint pen tip 10 that rotatably holds a ball having a diameter of 1.0 mm is attached to the front end of the ink storage cylinder 8 included in the ballpoint pen refill 7 via a tip holder 9.
Further, a tail plug 11 having an air hole for communicating inside and outside is attached to the rear end portion of the ink storage cylinder 8.
The inside of the ink storage cylinder 8 is filled with the water-based ink composition 12 for writing tools and the ink follower 13 having the above-mentioned ink composition.
Although not shown, a coil spring is provided behind the ball to constantly press the ball against the inner wall of the front end of the chip.

Further, the rear end portion of the ink storage cylinder 8 included in the ballpoint pen refill 7 is press-fitted and mounted in the rear end portion of the rear shaft 3, and the portion of the ink storage cylinder 8 filled with the ink composition 12 and the ink follower 13. The space following is communicated with the outside air only by the communication hole 3A provided at the rear end of the rear shaft 3 that communicates inside and outside the writing instrument.

The pressurizing mechanism operated by fitting the cap 4 will be described in detail below.
By fitting the cap 4 to the rear shaft 3 of the writing instrument main body, pressure can be applied to the ink composition 12 filled in the ballpoint pen refill 7 via the ink follower 13.
Specifically, when the rear end portion of the rear shaft 3 is inserted in the direction of the arrow F in the figure on the open end side of the cap body 5, the inner wall 5A of the cap body 5 and the side wall 3B of the rear shaft 3 first come into contact with each other.
At this time, the space inside the cap body 5, the inside of the rear shaft 3, and the ink storage cylinder 8 are communicated in a sealed state through the communication hole 3A provided at the rear end of the rear shaft 3 for communicating inside and outside.
Further, when the cap 4 is advanced in the direction of the arrow F in the figure, the closed space is compressed until the fitting is completed. As a result, pressure can be applied to the water-based ink composition for writing tools filled in the ballpoint pen refill 7 via the ink follower 13. The pressure was 1050 hPa.

[handwriting]
The ink compositions of Examples and Comparative Examples were written on a writing paper (JIS P 3201 writing paper A), and the handwriting was visually observed to evaluate the three-dimensional effect, cracks, glossiness, and transparency. Each evaluation standard is as follows. The results obtained are shown in Table 1.
Three-dimensional effect ◎: When I touched the handwriting with my hand, I felt a sufficient excitement.
○: When I touched the handwriting with my hand, I felt the excitement.
Δ: When I touched the handwriting with my finger, I felt a swelling, but it was a little scarce.
X: When I touched the handwriting with my finger, I couldn't feel the excitement.
Crack ○: No crack was found in the handwriting.
Δ: Slight cracks were found in the handwriting.
X: Many cracks were found in the handwriting, and it collapsed when I touched it.
Glossy ○: Sufficient glossiness was confirmed in the handwriting.
X: Sufficient glossiness was not confirmed in the handwriting.
Transparency ○: The handwriting had sufficient transparency.
X: The handwriting could not be confirmed to be sufficiently transparent.
XX: Sufficient transparency could not be confirmed in the handwriting, and cloudiness was also confirmed.

The ink composition in which the amount of the thickener was changed from 4 to 2% by mass with respect to the ink composition of Comparative Example 2 had the same evaluation of cracks, glossiness, and transparency as that of Comparative Example 2.

Regarding the ink composition of the example, when the adhesiveness of the surface was confirmed by touching the handwriting one hour after writing by hand, all of them did not adhere to the hand and the adhesiveness was low.
Further, the ink composition of Example 6 did not rub even if the obtained handwriting was rubbed 10 minutes after writing, and the handwriting drying property was faster than that of the ink compositions of other examples. It was good.

1 Cap type pressure ballpoint pen 2 Front shaft 3 Rear shaft 3A Communication hole 3B Side wall 4 Cap 5 Cap body 5A Inner wall 6 Seal member 7 Ballpoint pen refill 8 Ink storage cylinder 9 Chip holder 10 Ballpoint pen tip 11 Tail plug 11A Air hole 12 Writing tool ink Composition 13 Ink follower 14 Grip

Claims (9)

A water-based ink composition for writing utensils, which comprises a film-forming polymer having a minimum film-forming temperature of 50 ° C. or less, an associated thickener, a colorant, and water.
A water-based ink composition for writing tools, wherein the ink composition has a viscosity of 50 mPa · s or more under the conditions of 20 ° C. and a shear rate of 1.92 sec ^-1 . The ink composition according to claim 1, wherein the association-type thickener is a urethane-based association-type thickener. The ink composition according to claim 1 or 2, wherein the film-forming polymer is an acrylic resin or a urethane resin. The ink composition according to any one of claims 1 to 3, further comprising a water-soluble resin. The ink composition according to any one of claims 1 to 4, wherein the solid content ratio of the ink composition is 10 to 50% by mass. Claims 1 to 5 in which the viscosity ratio of the ink composition (viscosity under the condition of 20 ° C., shear rate of 1.92 sec ^-1 / 20 ° C., viscosity under the condition of shear rate of 192 sec ^-1 ) is 10 or more. The ink composition according to any one of the above. A writing instrument comprising the composition according to any one of claims 1 to 6. The writing tool according to claim 7, which is a ballpoint pen. The writing instrument according to claim 7 or 8, which is a pressurized ballpoint pen.

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