JP4326867B2 - Water-based ink composition for ballpoint pen and ballpoint pen incorporating the same - Google Patents

Description

  The present invention relates to a water-based ink composition for ballpoint pens. More specifically, the present invention relates to a water-based ink composition for ballpoint pens and a ballpoint pen that exhibits excellent sag-preventing performance without impairing dry-up resistance at the nib.

Conventionally, as a ballpoint pen containing a water-based ink composition, an ink supply member (pen core) that adjusts the amount of ink supplied from the ink containing portion to the pen tip, or one end directly or via a relay member Some ink is stored directly in an ink storage tube fitted with a ballpoint pen tip.
Among them, in ballpoint pens using ink supply members, air enters and exits along with changes in the internal pressure of the ink container due to ink consumption and temperature changes. May sag.
Also, in the ballpoint pen that contains ink directly in the ink containing tube, when the viscosity of the ink to be stored is high, it becomes difficult to obtain a good writing feeling or line breakage in the handwriting, conversely, when the viscosity of the ink is low, The ink is excellent in ink discharge property and gives a good writing feeling, but the ink may hang down when left in the pen point downward state. In particular, when a ballpoint pen is used that does not have a cap, etc. and the pen tip is always exposed to the outside air and is housed in the shaft cylinder, moisture evaporation from the pen tip is significant and writing is impossible in a short time. Therefore, it is necessary to add an additive to the ink for the purpose of improving the dry-up resistance. However, when a large amount of a water-soluble organic solvent, a wetting agent such as polyhydric alcohol, urea, or the like is added as the additive in order to satisfy dry-up resistance, the ink viscosity is increased and writing defects are likely to occur. In some cases, there are problems such as that the ink does not dry for a long time, or that the pen tip easily hangs down when left in the pen tip downward state.
Japanese Patent Publication No. 5-54875

  The present invention solves the above-mentioned conventional problems, that is, a ball-point pen that exhibits excellent sag-preventing performance without impairing dry-up resistance, and has less handwriting blur even in low-viscosity inks. Another object of the present invention is to provide a water-based ink composition and a ballpoint pen incorporating the same.

The present invention is an aqueous ink composition comprising at least water, a colorant, a water-soluble organic solvent, and carboxymethylcellulose sodium salt, wherein the carboxymethylcellulose sodium salt is a B-type viscometer (20 ° C., with viscosity of a 1% strength aqueous solution is 20~1000mPa · s at 30 rpm), the degree of substitution with carboxymethyl groups (degree of etherification) of Ri der 0.7 to 1.3, B-type viscometer (20 ° C., The ink viscosity at 30 rpm) is 5 to 20 mPa · s . Furthermore, 0.1 to 1% by weight of the carboxymethylcellulose sodium salt is contained in the ink composition, and 0.5 to 5% by weight of resin particles and / or wax emulsion is contained in the ink composition. Requirement. Furthermore, it is required to be a ballpoint pen containing the ink composition.

  In the present invention, the viscosity of the ink is within a range where the writing feeling is not impaired by adding a carboxymethyl cellulose sodium salt having a viscosity and a substitution degree (etherification degree) of a carboxymethyl group to the aqueous ink composition. As the moisture in the ink evaporates from the nib in the cap-off state, the carboxymethylcellulose sodium salt forms a film having an appropriate strength on the nib. Accordingly, it is presumed that excellent ink sag performance is exhibited without impairing the dry-up resistance of the nib. In addition, in low-viscosity inks, handwriting blur can be suppressed by adding the carboxymethylcellulose sodium salt.

The carboxymethylcellulose sodium salt is a kind of water-soluble cellulose-based polymer, and one having one carboxymethyl group per anhydroglucose unit has a carboxymethyl group substitution degree (etherification degree) of 1.0.
As the carboxymethyl cellulose sodium salt added to the aqueous ink composition of the present invention, those having a degree of etherification in the range of 0.7 to 1.3 are preferably used. In general, the higher the degree of etherification of carboxymethylcellulose sodium salt, the higher the solubility (solubility) in water. Therefore, it is presumed that the degree of etherification affects the process of dry film formation during water evaporation. . In other words, carboxymethylcellulose sodium salt with a low degree of etherification can precipitate even with a small amount of water evaporation, so that it is easy to form a stronger film than usual, so that dripping of the ink can be suppressed, but the dry-up performance is impaired. . On the other hand, carboxymethylcellulose sodium salt having a high degree of etherification is less likely to precipitate during evaporation of water, so that the effect of suppressing ink dripping is low. Therefore, a carboxymethyl cellulose sodium salt having a solubility in a range that can suppress the drooping of ink without impairing the dry-up resistance is applied in a range of etherification degree of 0.7 to 1.3.
As the carboxymethylcellulose sodium salt added to the ink, one having a viscosity of 20 to 1000 mPa · s in a B-type viscometer (20 ° C., 30 rpm) in a 1% concentration aqueous solution is used. When a material with a viscosity higher than 1000 mPa · s is used, the viscosity of the ink increases with a small amount of addition, so the required amount cannot be added to the ink, and the film formation at the pen tip is not sufficient, resulting in sagging End up. On the contrary, when a material having a viscosity lower than 20 mPa · s is used, it is necessary to add a large amount in order to obtain a desired ink viscosity, so that dripping of the ink can be suppressed but the dry-up performance is impaired. .

The carboxymethylcellulose sodium salt can be added in the range of 0.1 to 1% by weight in the total amount of the ink composition.
If the amount is less than 0.1% by weight, it is difficult to suppress the drooping of the ink. If the amount exceeds 1% by weight, the drooping can be suppressed, but the cap-off performance is remarkably hindered, and the handwriting may be drowned or dull. Etc. may occur.

As the colorant, all dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof are illustrated below.
As the dye, an acid dye, a basic dye, a direct dye, or the like can be used.
As an acid dye,
New coccin (CI. 16255),
Tartrazine (C.I. 19140),
Acid Blue Black 10B (C.I. 20470),
Guinea Green (C.I.42085),
Brilliant blue FCF (C.I.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) or the like is used.

As basic dye,
Chrysoidine (C.I. 11270),
Methyl violet FN (C.I. 42535),
Crystal violet (C.I. 42555),
Malachite green (C.I. 42000),
Victoria Blue FB (C.I. 44045),
Rhodamine B (C.I. 45170),
Acridine orange NS (C.I. 46005),
Methylene blue B (C.I. 52015) or the like is used.

As a direct dye,
Congo Red (C.I. 22120),
Direct Sky Blue 5B (C.I. 24400),
Violet BB (C.I. 27905),
Direct deep black EX (CI 30235),
Caillas Black G Conch (C.I. 35225),
Direct Fast Black G (C.I. 35255),
Phthalocyanine blue (C.I. 74180) or the like is used.

Examples of the pigment include inorganic pigments such as carbon black and ultramarine, and organic pigments such as copper phthalocyanine blue and benzidine yellow, as well as water dispersion finely and stably dispersed in an aqueous medium in advance using a surfactant or resin. Pigment products and the like are used. I. Pigment Blue 15: 3B [Product name: Sandy Super Blue GLL, pigment content 24%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Red 146 [Product name: Sandye Super Pink FBL, pigment content 21.5%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. I. Pigment Red 220/166 [Product name: TC Red FG, pigment content of about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.].
As the resin for dispersing the pigment, polyamide resin, polyurethane resin, polyester resin, epoxy resin, melamine resin, phenol resin, silicone resin, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, Examples thereof include polystyrene, acrylic acid resin, maleic acid resin, gum arabic, cellulose, dextran, casein, and derivatives thereof, and copolymers of the above-described resins.
As the fluorescent pigment, a fluorescent pigment in the form of fine particles of synthetic resin in which various fluorescent dyes are formed into a solid solution in a resin matrix can be used.
In addition, white pigments such as titanium dioxide, metal powders such as aluminum, natural mica, synthetic mica, alumina, pearl pigments in which the surface of the core material is coated with a metal oxide such as titanium dioxide, cholesteric liquid crystal type glitter A functional pigment or the like can also be used.
The pigments can be used alone or in combination of two or more, and are used in the range of 1 to 25% by weight, preferably 2 to 15% by weight in the ink composition.

As the water-soluble organic solvent, conventionally used solvents that are compatible with water are used. Ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol , Hexylene glycol, 1,3-butanediol, neoprene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene Glycol monomethyl ether, propylene glycol Examples include monoethyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone and the like.
In addition, the said water-soluble organic solvent can also use 1 type (s) or 2 or more types together, and is used in 2-60 weight% in an ink composition, Preferably it is 5-35 weight%.

Further, in the ink composition of the present invention, resin particles and / or wax emulsion can be used in combination for the purpose of further improving the sag prevention performance.
The resin particles are fine particles of a single monomer polymer or a copolymer of two or more monomers, and may be either a solid state or an aqueous dispersion dispersed in an aqueous medium. The wax emulsion is an aqueous dispersion of a plant system such as carnauba, a mineral system such as montan, an animal system such as lanolin, a petroleum-based natural wax such as paraffin, and a synthetic wax.
The resin particles and / or wax emulsion is used in the range of 0.5 to 5% by weight in the ink composition. If it is less than 0.5% by weight, the dripping prevention performance cannot be improved, and if it is added in excess of 5% by weight, a film stronger than usual can be formed so that dripping of the ink can be suppressed, but the anti-drying performance is improved. You will lose.

In addition, a pH adjuster, an antiseptic, or an antifungal agent can be added as necessary.
Examples of the pH adjuster include inorganic basic salts such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide and sodium acetate, and organic basic compounds such as water-soluble amine compounds such as triethanolamine and diethanolamine.
Examples of the preservative or antifungal agent include carboxylic acid, sodium salt of 1,2-benzisothiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6 -Tetrachloro-4- (methylsulfonyl) pyridine and the like.
In addition, fluorine surfactants and nonionic, anionic, cationic surfactants, antifoaming agents such as dimethylpolysiloxane, catechins, antioxidants such as sodium ascorbate and derivatives thereof that improve the permeability of the solvent. It can also be added.

  In addition to the resin particles, one or two water-soluble resins such as alkyd resin, acrylic resin, styrene maleic acid copolymer, cellulose derivative, polyvinyl pyrrolidone, polyvinyl alcohol, and dextrin are used in a category that does not interfere with drying resistance. Add one or more seeds to improve handwriting fastness, or use 1 or 2 wetting agents such as urea, nonionic surfactants, sorbit, mannitol, sucrose, glucose, reduced starch hydrolysate, sodium pyrophosphate More than seeds can be added.

If necessary, a shear thinning agent can be added to the ink composition.
As the shear thinning agent, water-soluble or dispersible substances are effective. For example, xanthan gum, welan gum, and succinoglycan whose constituent monosaccharide is an organic acid-modified heteropolysaccharide of glucose and galactose ( 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, glucomannan, agar Thickening polysaccharides with gelling ability extracted from seaweed such as carrageenin, benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymer, inorganic fine particles, polyglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester Polyethylene glycol fatty acid ester, polyoxyethylene castor oil, polyoxyethylene lanolin, lanolin alcohol, beeswax derivative, polyoxyethylene alkyl ether / polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, fatty acid amide and the like having an HLB value of 8 -12 nonionic surfactants, salts of dialkyl or dialkenylsulfosuccinic acid, and the like can be exemplified, and these 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.
The shear thinning agent can be used in the range of 0.1 to 20% by weight in the ink composition.

In addition, a rust preventive agent, a lubricant, etc. can be added as needed.
Examples of the rust inhibitor include benzotriazole and derivatives thereof, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, ethylenediaminetetraacetate, saponin, and dialkylthiourea.
Examples of the lubricant include metal soap, polyalkylene glycol fatty acid ester, ethylene oxide addition type cationic activator, phosphate ester activator, thiocarbamate, dimethyldithiocarbamate and the like.
A particularly preferably used lubricant is a phosphate ester surfactant described in JP-B-1-13508.

  The viscosity of the water-based ink composition of the present invention is adjusted to a range of 5 to 20 mPa · s using a B-type viscometer (20 ° C., 30 rpm). When it is lower than 5 mPa · s, handwriting blur tends to occur, and when it is higher than 20 mPa · s, the handwriting may be broken or broken.

  The water-based ink composition for ballpoint pens of the present invention is filled in a ballpoint pen with a ballpoint tip attached to the writing tip and is put to practical use. The structure and shape of the ballpoint pen itself are not particularly limited, and a conventional one can be applied. For example, the ballpoint pen has an ink containing tube filled with an ink composition, and the ink containing tube is a ball. For example, a ballpoint pen in which a liquid stopper for preventing backflow is in close contact with the end face of the ink is communicated with the tip attached to the tip.

The ballpoint pen tip will be described in more detail. A tip formed by holding a ball in a ball holding portion obtained by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, or a metal material is cut by a drill or the like A chip formed by holding the ball in the ball holding part formed by the above, or a ball held in a chip formed by cutting a metal pipe or metal material, and the like that is urged forward by a spring body, etc. Can be applied.
The ball may be cemented carbide, stainless steel, ruby, ceramic, or the like.

As the ink containing tube for containing the ink composition, for example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate or the like is preferably used from the viewpoint of low ink evaporation and productivity. Further, by using a transparent, colored transparent, or translucent molded body as the ink containing tube, the ink color, the remaining ink amount, and the like can be confirmed.
In addition to directly connecting the chip to the ink storage tube, the ink storage tube and the chip may be connected via a connecting member.
The ink storage tube may be a refill type in which the refill is stored in a shaft tube, or the shaft tube itself having a tip attached to a tip is used as an ink container, and ink is directly applied to the shaft tube. It may be filled.

The back end of the ink composition housed in the ink housing tube is filled with an ink backflow prevention body.
The ink backflow preventer can be either liquid or solid, and the liquid ink backflow preventive includes non-volatile media such as polybutene and silicone oil. Aluminum silicate or the like can also be added.
Moreover, a resin molding is mentioned as a solid ink backflow prevention body.
Further, the liquid and solid ink backflow preventers can be used in combination.

  The present invention inhibits the nib dry-up resistance by adding a carboxymethyl cellulose sodium salt having a viscosity and a degree of substitution of carboxymethyl groups (degree of etherification) to a water-based ink composition. A water-based ink composition for a ballpoint pen that can exhibit excellent dripping prevention performance and can suppress handwriting bleeding in low-viscosity ink, and a ballpoint pen incorporating the same.

  The aqueous ink composition for a writing instrument of the present invention has a dye or pigment (pigment dispersion), a water-soluble organic solvent, and a 1% strength aqueous solution in a B-type viscometer (20 ° C., 30 rpm) in an aqueous medium having a viscosity of 20 to 20%. Carboxymethyl cellulose sodium salt having a substitution degree of carboxymethyl group (degree of etherification) of 0.7 to 1.3, a shear thinning agent and various additives as necessary, and added as necessary. It is prepared by warming and stirring, dissolving and dispersing, and used by filling in a ballpoint pen.

  Table 1 below shows examples, and Table 2 shows comparative examples. However, the present invention is not limited to these examples. In addition, the numerical value in a table | surface represents a weight part. The ink viscosity was measured at 20 ° C. and 30 rpm using a B-type rotational viscometer [manufactured by Tokyo Keiki Co., Ltd.].

The raw materials (1) to (15) in the table will be described below.
(1) Product name: Fisco Black 886, C.I. I. Direct black 154, density 15%
(2) Hodogaya Chemical Co., Ltd., trade name: Phloxine, C.I. I. 45410
(3) manufactured by Sumitomo Chemical Co., Ltd., trade name: Acid Blue PG, C.I. I. 42655
(4) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen F-SB, etherification degree 0.85 to 0.95, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 29 to 33 mP・ S
(5) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen F-SA, degree of etherification 0.7-0.8, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 51-54 mP・ S
(6) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen F-BSH, etherification degree 0.7-0.8, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 500-800 mP・ S
(7) Made by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen HE-90F, etherification degree 1.2-1.3, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 100-110 mP・ S
(8) Product name: John Wax 26, polyethylene wax emulsion, average particle size 0.069 μm, solid content 25%, manufactured by Johnson Polymer Co., Ltd.
(9) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf AL, phosphate ester surfactant (10) Avicia, trade name: Proxel XL-2, 1,2-benzothiazoline-3-one (11) Made by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen 7A, etherification degree 0.7-0.8, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 7-8 mP · s
(12) Made by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen F-BSH12, degree of etherification 0.65-0.75, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 6500-8000 mP・ S
(13) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Serogen PL-15, degree of etherification 0.45-0.55, 1% strength aqueous solution viscosity (B-type viscometer: 20 ° C., 30 rpm) 10-20 mP・ S
(14) Made by Sanki Co., Ltd., trade name: Kelzan (15) Made by BASF, trade name: Rubiscor K-30

Preparation of Ink After mixing each raw material other than carboxymethylcellulose sodium salt, xanthan gum and polyvinylpyrrolidone in the above blending amounts, stirring for 2 hours with Disper (20 ° C., 2000 rpm) and dissolving, carboxymethylcellulose sodium salt, xanthan gum, polyvinyl Pyrrolidone was added and stirred with a disper (20 ° C., 6000 rpm) for 1 hour to obtain a ballpoint pen ink.

  1 cc of the ink of the above example and the comparative ink was filled in a refill of a commercially available ballpoint pen [manufactured by Pilot Co., Ltd., trade name: Hitech Point VR5], and 0.1 g of ink backflow prevention was further prevented on the rear end surface of the ink. After filling the body (silicone grease system) and centrifuging, the refill was incorporated into a shaft tube to obtain a sample ballpoint pen.

The following tests were conducted with the sample ballpoint pens.
Sagging test A sample ball-point pen that has been confirmed to be writable can be held downward (inverted) with the pen tip exposed and in a non-contact state with the pen tip (ballpoint pen tip), and an environment with a temperature of 20 ° C and a relative humidity of 90% After being left for 20 hours, the state of the nib was visually observed.
Cap-off test A sample ball-point pen that has been confirmed to be writable can be left in a room (20 ° C) for 30 days with the pen tip exposed, and then handwritten on JIS P3201 writing paper A in a line. Twelve consecutive writings were made, and the number of pieces that can be normally written was visually observed.
Writing test A sample ball-point pen that was confirmed to be writable was handwritten on JIS P3201 writing paper A by hand and twelve consecutive circles were written in a line, and the handwriting was visually observed.
Bleeding test A sample ball-point pen that was confirmed to be writable was drawn by hand on a JIS P3201 writing paper A, and the presence or absence of handwriting bleeding was visually observed.
The results of the test are shown in the following table.

The evaluation of the test results is as follows.
Sag test ○: No abnormality.
Δ: Ink droplets are observed at the tip of the chip.
X: A large ink droplet is observed at the tip of the chip, or ink drops from the tip of the chip occur.
Cap-off test ○: Writing is possible within one circle.
Δ: Written within 1 line.
×: Cannot write within 1 line, or cannot write.
Written test ○: No abnormality.
Δ: Slightly frayed.
X: A crack or a line crack occurs.
Bleeding test ○: No abnormality.
X: There is bleeding.

Claims (4)

An aqueous ink composition comprising at least water, a colorant, a water-soluble organic solvent, and carboxymethylcellulose sodium salt, wherein the carboxymethylcellulose sodium salt is 1 in a B-type viscometer (20 ° C., 30 rpm). % the viscosity of the concentration aqueous solution with a 20~1000mPa · s, carboxymethyl degree of substitution by methyl groups (degree of etherification) of Ri der 0.7-1.3, ink in the B-type viscometer (20 ° C., 30 rpm) A water-based ink composition for ballpoint pens having a viscosity of 5 to 20 mPa · s .   The aqueous ink composition for ballpoint pens according to claim 1, comprising 0.1 to 1% by weight of the carboxymethylcellulose sodium salt in the ink composition. The water-based ink composition for a ballpoint pen according to claim 1 or 2, wherein the ink composition comprises 0.5 to 5% by weight of resin particles and / or a wax emulsion. A ballpoint pen incorporating the ink composition according to any one of claims 1 to 3.