JP2017095582A - Aqueous ink composition for ball-point pen and ball-point pen including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress ink dripping regardless of ink viscosity even if the ink flow path of a pen tip is widened during use or storage, and even a ballpoint pen provided with a small-diameter ball causes writing defects. Providing a water-based ink composition for a ballpoint pen that can exhibit excellent writing performance over a long period of time, and a ballpoint pen incorporating the composition. An aqueous ink composition composed of water, a colorant, and resin particles, wherein the resin particles have a substantially uniform particle size in the range of 0.1 to 2 μm of primary particles. A water-based ink composition for ball pens, which is a secondary particle state in which the average diameter in the ink is dispersed in a range of 1.2 to 2.5 times the average diameter of the primary particles. A ballpoint pen containing the water-based ink composition for a ballpoint pen. A water-based ink composition for bopen, in which the resin particles are preferably acrylic resin particles, and further added in the range of 0.1 to 5% by weight in the total amount of the ink composition. [Selection diagram] None

Description

  The present invention relates to a water-based ink composition for ballpoint pens. Furthermore, the present invention relates to a water-based ink composition for ballpoint pens that can suppress ink sag and a ballpoint pen using the same.

2. Description of the Related Art Conventionally, many ballpoint pens have been put on the market in which water-based ink is directly built in an ink storage tube and a ballpoint pen refill having an ink backflow preventer at the rear end of the ink is stored in a shaft cylinder.
In particular, in a retractable ballpoint pen that does not have a cap, ink droplets accumulate at the tip of the pen tip when stored in a state where the tip of the pen point downwards, so-called sag is likely to occur, so it is suppressed by adjusting the viscosity of the ink to be stored. ing. When the ink to be stored has a relatively high viscosity, the ink dripping from the pen tip can be suppressed to some extent, but there is a possibility that the writing performance may be deteriorated, for example, the dry-up performance is deteriorated or the handwriting is broken.
On the other hand, when using low-viscosity ink to satisfy the writing performance, when paper fibers are sandwiched between the ball and the small mouth during writing or displayed in a pressed state of the ball, or when dropped, etc. When the ink flow passage is widened by scratching or deforming the tip, ink drooping or dripping may occur (for example, see Patent Documents 1 and 2).
In view of this, a technique has been found and added by adding a resin emulsion to the ink to suppress ink drooping or dripping while maintaining writing performance (see Patent Document 3).

JP 2004-291632 A JP 2004-217729 A JP 2007-177011 A

By uniformly dispersing the resin emulsion, the resin emulsion is maintained in a stable state in the ink, and the pen tip (by agglomeration) can form a coating film to effectively suppress dripping of the ink. . Moreover, since the effect which suppresses dry-up of a nib is acquired by the said coating film, it is useful.
However, in a ballpoint pen with a small ball diameter, the exposed area of the pen tip is small and the ink flow path is narrow, so that a strong coating film is formed, and ink ejection is hindered and the handwriting tends to be distorted. there were.

  The present invention solves the problem that occurs when the pen tip of the ballpoint pen is exposed, that is, even when the ink flow path of the pen tip is widened during use or storage, the ink viscosity is reduced. Water-based for ballpoint pens that can effectively suppress ink sag without being affected, and can exhibit excellent writing performance over a long period of time without causing poor writing even with ballpoint pens with small diameter balls An ink composition and a ballpoint pen incorporating the ink composition are provided.

The present invention is a water-based ink composition comprising at least water, a colorant, and resin particles, wherein the resin particles are a group of spherical particles having a substantially uniform particle diameter, and the average diameter of the primary particles is 0.00. Requirements for a water-based ink composition for ballpoint pens in the secondary particle state in which the average diameter in the ink is in the range of 1 to 2 μm and the average diameter in the ink is 1.2 to 2.5 times the average diameter of the primary particles. And
Furthermore, it is required that the resin particles are acrylic resin particles and that the resin particles are added in a range of 0.1 to 5% by weight in the total amount of the ink composition.
Furthermore, it is a requirement that a ballpoint pen containing any one of the above-mentioned water-based ink compositions for ballpoint pens, the ballpoint diameter of the pen point is 0.28 to 0.7 mm, and that the ballpoint pen is in a retractable form. And

  According to the present invention, without drastic adjustment of the ink viscosity, even if the ink flow path of the nib is inadvertently expanded, ink drooping and dripping can be effectively suppressed. In addition, a ballpoint pen having a small-diameter ball can provide a water-based ink composition for a ballpoint pen that can exhibit excellent writing performance over a long period of time without causing poor writing, and a ballpoint pen using the same.

In the present invention, a spherical resin particle group having a substantially uniform particle diameter in which the average diameter of primary particles is in the range of 0.1 to 2 μm is selected from 1.2 to 2.2. It is added to the water-based ink composition in the form of secondary particles dispersed so as to be in the range of 5 times.
Therefore, it may be dispersed as secondary particles without being dissolved in an aqueous medium and may be substantially spherical resin particles having the average diameter. Examples of the material include melamine resin, acrylic resin, urethane resin, silicone resin, and phenol. General-purpose materials such as resin can be applied. In particular, since acrylic resin has a low specific gravity, it is excellent in dispersion stability in ink as secondary particles.
As a result, it is possible to suppress the drooping of the ink without being influenced by the ink viscosity, and in particular, even when the ink flow path is unexpectedly widened, the secondary particulate spherical resin blocks the ink flow path. It is possible to suppress dripping of ink and dropping of ink. In addition, since no coating film is formed with the pen tip, the secondary particles that block the ink flow path are easily separated from the aggregated state and become primary particles during writing. It will be possible to write without fail.

  In addition, the primary particles having an average diameter of 0.1 to 2 μm dispersed so that the primary particles are 1.2 to 2.5 times as large as the primary particles, the primary particles having the same size as the secondary particles are dispersed in the ink. Compared to the case where it is added to the ink, it exhibits a high drooping suppression effect, but when applied to a ballpoint pen with a small ball diameter that narrows the ink flow path, the narrow space is closed with secondary particles, so when writing Since ink can be ejected by separating into primary particles, writing can be performed without clogging a narrow ink flow path. Therefore, it is particularly useful when the ball diameter of the nib is 0.28 to 0.7 mm, preferably 0.28 to 0.5 mm, more preferably 0.3 to 0.4 mm.

When the average diameter of the primary particles is less than 0.1 μm, it is difficult to block the deformed ink flow path even when the particles become secondary particles, so that the ink droops easily. In this case, it is difficult for the ink to flow out from the ink flow path, and handwriting scraping is likely to occur during writing. In particular, the average primary particle diameter is preferably 0.1 to 1 μm.
In addition, when the particle size of the secondary particles is smaller than 1.2 times the particle size of the primary particles, it is almost the same as the effect obtained as a single particle. Separation may not be possible, and ink ejection with a small-diameter ball may be hindered.
In addition, the average particle diameter of a primary particle and a secondary particle is measured using a commercially available particle diameter measuring apparatus, and is represented by the median diameter in a volume reference particle size distribution.

  The resin particles are blended in the range of 0.1 to 5% by weight, preferably 0.2 to 3% by weight, based on the total amount of the ink composition. If it is less than 0.1% by weight, it is difficult to obtain a drooping prevention effect, and even if it exceeds 5% by weight, no improvement is observed, so no further addition is required.

As the colorant, all dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof will be exemplified below.
As the dye, an acid dye, a basic dye, a direct dye, or the like can be used.
Examples of the acid dye include New Coxin (CI. 16255), Tartrazine (CI. 19140), Acid Blue Black 10B (CI. 20470), Guinea Green (CI. 42085), Brilliant Blue FCF. (CI.42090), Acid Violet 6B (C.I.42640), Soluble Blue (C.I.42755), Naphthalene Green (C.I.44025), Eosin (C.I.45380), Phloxin (C.I. 45410), erythrosine (C.I. 45430), nigrosine (C.I. 50420), acid flavin (C.I. 56205) and the like are used.
Examples of basic dyes include chrysoidine (C.I. 11270), methyl violet FN (C.I. 42535), crystal violet (C.I. 42555), malachite green (C.I. 42000), Victoria blue FB ( CI 44045), rhodamine B (C.I. 45170), acridine orange NS (C.I. 46005), methylene blue B (C.I. 52015) and the like are used.
As direct dyes, Congo Red (C.I. 22120), Direct Sky Blue 5B (C.I. 24400), Violet BB (C.I. 27905), Direct Deep Black EX (C.I. 30235), Kaya Las Black G Conch (C.I. 35225), Direct Fast Black G (C.I. 35255), Phthalocyanine Blue (C.I. 74180) and the like are used.

Examples of the pigment include inorganic pigments such as carbon black and ultramarine blue, and organic pigments such as copper phthalocyanine blue and benzidine yellow, as well as water-dispersed pigments that are finely and stably dispersed in an aqueous medium in advance using a surfactant or the like. For example, C.I. I. Pigment Blue 15: 3B [Product Name: S.P. S. Blue GLL, pigment content 22%, manufactured by Sanyo Color Co., Ltd.], C.I. I. Pigment Red 146 [Product Name: S.P. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Dye Co., Ltd.], C.I. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.], C.I. I. Pigment Red220 / 166 [Product name: TC Red FG, pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.].
As the fluorescent pigment, a fluorescent pigment in the form of fine particles of a synthetic resin in which various fluorescent dyes are formed into a solid solution in a resin matrix can be used.
In addition, pearl pigments, gold and silver metallic pigments, phosphorescent pigments, white pigments such as titanium dioxide, metal powders such as aluminum, thermochromic compositions, photochromic compositions, perfumes, etc. directly or microcapsules Examples of the capsule pigments are as follows.

The thermochromic composition includes (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reversible thermochromic composition comprising a reaction medium that determines the temperature at which the color reaction occurs. The composition is suitable and is encapsulated in microcapsules and applied as a reversible thermochromic microcapsule pigment.
Examples of the reversible thermochromic composition include those described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc., at a predetermined temperature (discoloration point). Discolored before and after, decolored state in the temperature range above the high temperature side discoloration point, color development state in the temperature range below the low temperature side discoloration point, only one specific state exists in the normal temperature range among the two states, The other state is maintained as long as the heat or cold required to develop the state is applied, but when the heat or cold is no longer applied, the hysteresis width returns to the state exhibited in the normal temperature range. A heat decolorable microcapsule pigment in which a reversible thermochromic composition having relatively small characteristics (ΔH = 1 to 7 ° C.) is encapsulated in a microcapsule can be applied.
Furthermore, comparatively large hysteresis characteristics (ΔH = 8 to 50) described in JP-B-4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936, and the like. ° C), and exhibit large hysteresis characteristics described in JP-A-2006-137886, JP-A-2006-188660, JP-A-2008-45062, JP-A-2008-280523, In other words, the shape of the curve plotting the change in color density due to temperature change differs greatly between when the temperature is raised from the lower temperature side than the color change temperature range and when the temperature is lowered from the higher temperature side than the color change temperature range. The color changes following the path, and the color development state in the low temperature range below the complete color development temperature, or the color erase state in the high temperature range above the complete color erase temperature is in the specific temperature range. Microcapsule pigment was contained a reversible thermochromic composition heated decolorizable having chroma memory property can be applied.
Specifically, as the reversible thermochromic composition having color memory, a complete color development temperature can be obtained only in a freezing room, a cold district, etc., that is, −50 to 0 ° C., preferably −40 to − 5 ° C., more preferably −30 to −10 ° C., and complete decoloring temperature obtained from a frictional heat generated by a friction body, a heating body such as a hair dryer, that is, 50 to 95 ° C., preferably 50 to 90 ° C. More preferably, by specifying the range of 60 to 80 ° C. and specifying the ΔH value of 40 to 100 ° C., it is possible to effectively function to maintain the color exhibited in the normal state (daily life temperature range).

  The colorant can be used singly or in combination of two or more, and is used in the range of 1 to 35% by weight, preferably 2 to 30% by weight in the ink composition.

Further, if necessary, a conventional general-purpose water-soluble organic solvent compatible with water can be used. Specifically, ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol mono Examples include ethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.
In addition, the said water-soluble organic solvent can be used 1 type or in combination of 2 or more types, and is used in 2 to 60 weight%, Preferably it is 5 to 35 weight%.

  Furthermore, a water-soluble resin can be added in order to impart adhesion and viscosity to the paper surface. Examples of the water-soluble resin include alkyd resins, acrylic resins, styrene maleic acid copolymers, cellulose derivatives, polyvinyl pyrrolidone, polyvinyl alcohol, and dextrin. The water-soluble resin can be used alone or in combination of two or more, and is used in the range of 1 to 30% by weight in the ink composition.

In addition, pH adjusters such as inorganic salts such as sodium carbonate, sodium phosphate and sodium acetate, organic basic compounds such as water-soluble amine compounds, benzotriazole, tolyltriazole, 2,5-dimercapto- Rust preventives such as 1,3,4-thiadiazole, saponin, coalic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3 , 5,6-tetrachloro-4- (methylsulfonyl) pyridine, etc., antiseptic or antifungal agent, urea, nonionic surfactant, sorbit, mannitol, sucrose, glucose, reduced starch hydrolyzate, pyrophosphate Wetting agents such as sodium, antifoaming agents, fluorosurfactants and noni that improve ink permeability The emissions-based surfactant may be used.
Furthermore, ascorbic acids, erythorbic acids, α-tocopherol, catechins, synthetic polyphenols, kojic acid, alkylhydroxylamine, oxime derivatives, α-glucosylrutin, α-lipoic acid, phosphonate, phosphinate, sulfite, sulfoxyl Bubbles can also be removed chemically by adding acid salts, dithionites, thiosulfates, thiourea dioxide or the like.
Further, oligomers of N-vinyl-2-pyrrolidone, oligomers of N-vinyl-2-piperidone, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, N-vinyl-ε-caprolactam By adding a thickening inhibitor such as an oligomer, it is possible to enhance the function in the intruding form.
Further, a lubricant can be added, for example, metal soap, polyalkylene glycol fatty acid ester, ethylene oxide addition type cationic surfactant, phosphate ester type surfactant, β-alanine type surfactant, N-acyl amino acid, N-acylmethyltaurine, 2,5-dimercapto-1,3,4-thiadiazole and its salts and oligomers, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate , Α-lipoic acid, condensates of N-acyl-L-glutamic acid and L-lysine, salts thereof, and the like are used.

In addition, a shear thinning agent can be added to the ink composition. For example, xanthan gum, welan gum, or a constituent monosaccharide that is soluble or dispersible in water is an organic acid-modified heteropolysaccharide of glucose and galactose. Succinoglycan (average molecular weight of about 1 to 8 million), guar gum, locust bean gum and derivatives thereof, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 based on alkyl esters of methacrylic acid, Glycomannan, thickening polysaccharide with gelling ability extracted from seaweed such as agar and carrageenin, benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymer, inorganic fine particles, polyglycerin fatty acid ester, polyoxy Ethylene sorbitan Nonionic surfactants having a HLB value of 8 to 12, such as fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene alkyl ether / polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, fatty acid amide, dialkyl or dialkenyl sulfosucci Acid salts and the like can be exemplified, and they can be used alone or in combination.
Furthermore, a mixture of N-alkyl-2-pyrrolidone and an anionic surfactant, a mixture of polyvinyl alcohol and an acrylic resin can also be used.
Ink shear thinning is a rheological property that has a high viscosity and is difficult to flow in a static state or when stress is low, and it exhibits low fluidity and good fluidity when stress increases. It means liquidity called pseudo plasticity.

  The ink composition of the present invention exhibits the above-mentioned effects regardless of the viscosity, but it is a low-viscosity ink that is particularly disadvantageous for sag (for example, the measured value at 20 ° C. is in the range of 1 to 1000 mPa · s. High effect is demonstrated. The ink satisfying the above-described viscosity can satisfy the sagging and drying resistance, and also can satisfy the writing performance, that is, writing feeling, initial writing, handwriting drying property and good handwriting formation.

The ball-point pen filled with the water-based ink composition for ball-point pens will be described.
The ballpoint pen tip that becomes the writing tip is, for example, a metal cut and formed with a ball receiving seat and an ink lead-out portion inside, a plurality of inward protruding portions on the inner surface near the tip of the metal pipe from the outer surface It can be applied by pressing deformation, and an ink outflow gap extending radially outward from the center portion can be applied between the inward protruding portions. The contact area is relatively small, and a smooth writing feeling can be provided at a low writing pressure.
The ball held by the ballpoint pen tip is 0.1 to 2.0 mm in outer diameter of cemented carbide, stainless steel, ruby, ceramic, etc., preferably 0.2 to 1.2 mm, more preferably 0.28 to A 0.7 mm ball is effective.
The ballpoint pen tip is provided with a resilient member for projecting the rear end of the ball forward in the tip, and when not writing, the ball is pressed against the inner edge of the tip of the tip to bring it into close contact, and when writing, it is The ball can be retracted to allow ink to flow out, and ink leakage when not in use can be suppressed.
Examples of the elastic member include a metal thin wire spring, a member provided with a straight portion (rod portion) at one end of the spring, a linear plastic processed body, and the like, and can be pressed by an elastic force of 5 to 40 g. Applied.

For example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate is preferably used as the shaft cylinder that accommodates the water-based ink composition in terms of low ink evaporation and productivity.
In addition to directly connecting the tip to the shaft tube, the shaft tube and the chip may be connected via a connecting member.
When the ink composition is low in viscosity, the ink composition accommodated in the shaft cylinder includes a method of mounting an ink retaining member at the front of the shaft cylinder and storing the ink composition directly in the shaft cylinder, Examples of the method include impregnating the ink composition into a material body or a fiber processed body.

Furthermore, by using a transparent, colored transparent, or translucent molded body as the shaft tube, it is possible to confirm the ink color, the remaining amount of ink, and the like.
The shaft tube may be a ballpoint pen refill that accommodates the refill in the outer shaft, or the shaft tube with the tip mounted on the tip itself is used as an ink container and directly in the shaft tube. You may fill with ink.

The ballpoint pen using the shaft tube can be applied to either a cap type or a retractable type. The retractable ballpoint pen is stored in the outer shaft with the writing tip provided on the ballpoint pen refill exposed to the outside air, and the writing tip protrudes from the opening of the outer shaft by the operation of the retracting mechanism. Anything can be used. Since the pendulum ballpoint pen is in a state where the pen tip is always exposed to the outside air, the ink composition of the present invention is particularly effective.
Examples of the operation method of the retracting mechanism include a knock type, a rotary type, and a slide type.
The knock type has a knock portion on the outer shaft rear end portion or the outer shaft side surface, and by pressing the knock portion, the writing pen tip portion of the ballpoint pen refill is caused to protrude or retract from the outer shaft front end opening portion, or on the outer shaft. By pressing the provided clip portion, a configuration in which the writing tip portion of the ballpoint pen refill is projected and retracted from the outer shaft front end opening portion can be exemplified.
The rotary type can be exemplified by a configuration in which a rotating portion (rear shaft or the like) is provided on the outer shaft, and the writing tip portion of the ballpoint pen refill is projected and retracted from the outer shaft front end opening by turning the rotating portion.
The slide type has a slide part on the side surface of the shaft tube, and the writing tip part of the ball-point pen refill is projected and retracted from the front end opening part of the outer shaft by operating the slide, or the clip part provided on the outer shaft is slid. By doing so, it is possible to exemplify a configuration in which the writing tip portion of the ballpoint pen refill is projected and retracted from the outer shaft front end opening.
The retractable ballpoint pen may be a composite retractable ballpoint pen that accommodates a plurality of ballpoint pen refills in addition to a ballpoint refill accommodated in the outer shaft. Further, the ink storage tube constituting the ballpoint pen refill may be made of resin or metal.

The back end of the ink stored in the ballpoint pen refill can be filled with an ink backflow prevention body.
The ink backflow prevention body composition is composed of a non-volatile liquid or a hardly volatile liquid.
Specifically, petroleum jelly, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, Examples thereof include polyether-modified silicone oil and fatty acid-modified silicone oil, and one or more can be used in combination.

It is preferable to add a gelling agent to the non-volatile liquid or the hardly volatile liquid to increase the viscosity to a suitable viscosity. Hydrophobized silica on the surface, fine-particle silica whose surface is methylated, aluminum silicate, swelling Clay-based thickeners such as bentonite and montmorillonite treated with hydrophobic mica, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, zinc stearate, tribenzylidene sorbitol, fatty acid amide, amide-modified polyethylene wax And dextrin compounds such as hydrogenated castor oil and fatty acid dextrin, and cellulose compounds.
Furthermore, the liquid ink backflow prevention body composition and a solid ink backflow prevention body composition can be used in combination.

Examples will be described below, but the present invention is not limited to these examples.
The following table shows compositions and viscosities of water-based inks for ballpoint pens of Examples and Comparative Examples. In addition, the numerical value of a composition in a table | surface shows a weight part.
The average particle size of the resin particles (primary particles and secondary particles) used in each example and comparative example was measured using a particle size distribution measuring apparatus (Microtrac Bell, Nanoflex) using a dynamic light scattering method. And obtained by calculating the median diameter based on volume. The ink viscosity was measured at 1 rpm using an ELD type or EMD type rotational viscometer [manufactured by Tokyo Keiki Co., Ltd.] at 20 ° C.

The contents of the raw materials in the table will be described along the note numbers.
(1) Product name: Acid Blue PG, manufactured by Sumitomo Chemical Co., Ltd.
(2) Eisen Hodogaya Co., Ltd., trade name: Phloxine (3) Fuji Pigment Co., Ltd., trade name: Fuji SP Black 8922 (solid content: 20%)
(4) 2.0 parts of 3- (4-diethylamino-2-hexyloxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide as component (a), (b) A reversible thermochromic composition comprising 8.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane as a component and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) was included. Microcapsule pigment (T ₁ : −14 ° C., T ₂ : −6 ° C., T ₃ : 48 ° C., T ₄ : 60 ° C., ΔH: 64 ° C., average particle size: 2.3 μm, color change from blue to colorless )
(5) Product name: MP-1000, manufactured by Soken Chemical Co., Ltd.
(6) Product name: Techpolymer SSX-101, manufactured by Sekisui Plastics Co., Ltd.
(7) Toshiba Silicone Co., Ltd., trade name: Tospearl 120
(8) Product name: Chemipearl W401, manufactured by Mitsui Chemicals, Inc.
(9) Product name: Prisurf AL, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
(10) Alkali thickened acrylic emulsion, manufactured by Rohm & Haas Japan, trade name: Primal ASE-60

Preparation of ink Each raw material excluding the thickener was mixed in the blending amount of each Example and Comparative Example, and after stirring at 20 ° C. with a disper at 400 rpm for 1 hour, the one containing the thickener was further added. A ballpoint ink composition was obtained by stirring for 1 hour.
In each resin particle, the primary particle in Table 1 is a measured value measured directly by a measuring device, and the secondary particle (larger than the primary particle) is placed in a disperse so as to have a desired particle diameter in an aqueous medium. It is a measured value measured after stirring and adjusting.

Preparation of ballpoint pen refill The ballpoint pen refill consists of a pipe-type ballpoint pen tip (which contains a ball push spring that bounces the ball forward) and a ballpoint tip attached to the front. A member, an ink storage tube in which the connecting member is fixed to the front end opening, and an ink and an ink backflow prevention body are stored inside, and a tail plug fixed to the rear end opening of the ink storage tube . The ink backflow preventer is an ink backflow preventer kneaded using polybutene as the base oil and fatty acid amide as the thickener.
The ball pen refill used was two types of balls having a diameter of 0.3 mm and 0.7 mm.

Production of Ballpoint Pens Each of the above ballpoint pen refills was housed in a rear-biased state by a spring (coil spring) in a shaft cylinder provided with a clip on the rear outer surface to obtain two types of sample ballpoint pens. The ball-point pen has a retractable form in which a ball-point pen tip projects outward from a tip hole of the shaft cylinder by knocking a rear end portion (knock operation portion) of the shaft cylinder forward.

The following tests were conducted with the sample ballpoint pens.
Sagging test A
Using each ball-point pen, the ball-point pen tip was exposed from the shaft tube, and the tip was held downward. The tip was left in an atmosphere of a temperature of 20 ° C. and a relative humidity of 90% for 20 hours, and then the appearance of the tip of the tip was visually observed.
Sagging test B
After making small scratches on the tip of each ballpoint pen tip of each ballpoint pen, the tip was left in an atmosphere of a temperature of 20 ° C. and a relative humidity of 60% for 20 hours, and the appearance of the tip of the tip was visually observed.
Writing Test Each ball-point pen that was confirmed to be writable was centrifuged at 2000 rpm for 10 minutes, and then a straight line was handwritten on JIS P3201 writing paper A and the state of the handwriting was visually observed.
Ink stability test 5 g of each prepared ink was transferred to a sample bottle, covered, and allowed to stand at 20 ° C. for 30 days. Thereafter, the state of the ink was visually confirmed.

The test results are shown in the following table.

The contents of the test result evaluation symbols are as follows.
Sag test A, B
○: No ink sag.
Δ: Ink oozes out from the tip of the chip.
X: Ink droplets are observed at the tip of the chip.
Written test ○: A handwriting with a certain density and line width is obtained.
Δ: Scratch occurs in the handwriting.
X: Writing is impossible.
Ink stability test ○: No change in a uniform state.
Δ: A precipitate is observed.
X: Separated into two layers.

Claims (6)

A water-based ink composition comprising at least water, a colorant, and resin particles,
The resin particles are a group of spherical particles having a substantially uniform particle diameter, the average diameter of the primary particles is in the range of 0.1 to 2 μm, and the average diameter in the ink is 1.2 of the average diameter of the primary particles. A water-based ink composition for ballpoint pens in a secondary particle state dispersed in a range of up to 2.5 times.   The water-based ink composition for ballpoint pens according to claim 1, wherein the resin particles are acrylic resin particles.   The water-based ink composition for ball-point pens according to claim 1 or 2, wherein the resin particles are added in an amount of 0.1 to 5% by weight based on the total amount of the ink composition.   The ball-point pen which incorporated the water-based ink composition for ball-point pens in any one of the said Claim 1 thru | or 3.   The ballpoint pen according to claim 4, wherein the ball diameter of the nib is 0.28 to 0.7 mm.   The ballpoint pen according to claim 4 or 5, wherein the ballpoint pen is in a retractable form.