JP2002080770A - Water-based ink composition for writing utensil and writing utensil containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based ink composition for writing utensils capable of affording favorable handwritings through preventing bubble generation therein, and to provide writing utensils containing the ink. SOLUTION: This ink composition for writing utensils comprises a colorant, water, a water-miscible organic solvent, a shearing viscosity-diminishing agent, and at least one compound selected from sulfites, sulfoxylates, dithionites and thiosulfates. The other objective writing utensils containing the ink composition are also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink composition for a writing implement and a writing implement incorporating the same. More specifically, the present invention relates to a water-based ink composition for a writing instrument exhibiting a shear thinning property, and a writing instrument filled with the ink and an ink backflow preventive that follows with the consumption of the ink.

[0002]

2. Description of the Related Art An aqueous ballpoint pen ink composition containing a shear-thinning agent such as a high molecular weight polysaccharide has been disclosed as a water-based ink having a shear-thinning property (Japanese Patent Application Laid-Open No. HEI 4 (1999)).
-2144782). This type of ink has a high viscosity at rest when no shear stress is applied, and is stably held in the mechanism.In writing, the high shearing force of the high-speed rotating ball reduces the ink near the ball. As a result, the ink is ejected from the gap between the ball and the ball container and transferred to the paper. Since the ink transferred to the paper surface is released from the shearing force, it becomes a high-viscosity state again, and does not cause blur of the handwriting, which is a drawback of the conventional aqueous ink composition. Further, ink leakage does not occur depending on the above-mentioned shear thinning, and a flow rate adjusting member (pen core) for adjusting the ink flow rate is not required.
A writing instrument with a simple structure can be obtained. The above-described writing implement using the water-based ink exhibiting shear thinning has a simple structure, and since the air does not enter into the inside with the consumption of the ink as in the writing implement using the flow rate adjusting member, the internal pressure is reduced. While it has the advantage of little change and not causing ink dropping, special considerations are required when preparing and filling the ink. This prevents the solvent in the ink from evaporating on the rear end face of the ink, or prevents the ink from flowing backward when the writing tip is in an upright state (upright state). This is because the backflow preventer (liquid stopper) is filled, and the ink exists in an airtight space that is shut off from the outside air. If gas is mixed in the ink, the gas collects over time and bubbles are generated. This is because it is generated and adversely affects ink ejection during writing, and writing may not be possible if bubbles are present at the writing tip. In order to solve the above-mentioned problem, defoaming treatment for mechanically removing gas in ink is mainly performed, but it is difficult to perform sufficient defoaming by this method alone, and gas remains in ink. There is. In addition, when a colorant insoluble in a solvent such as a pigment, metal powder, or titanium oxide is used, if a treatment such as centrifugal defoaming is performed, the colorant is unevenly distributed in the ink container. Therefore, a method of chemically removing gas in the ink is considered. For example, an ascorbic acid derivative is added (Japanese Patent Publication No. 7-113101),
α-tocopherol may be added (Japanese Unexamined Patent Publication No.
No. 672) and further attempts to add catechins (JP-A-10-298483).

[0003]

However, among the compounds that chemically remove the gas in the ink, ascorbic acid derivatives are liable to cause the aggregation of the pigment in a system using a pigment as a coloring agent, so that practical use is not possible. Limited.
In addition, α-tocopherol is insoluble in water and is separated over time, making it difficult to permanently remove gas. Also,
The catechins are not limited to a coloring agent to be applied, and the gas removing function does not cause problems such as disappearing in a short period of time. For this reason, the purity is low, and the number of functional groups that exhibit gas reducibility and remove gas is small, so that a large amount must be added to obtain a desired effect. The present invention provides a water-based ink composition for a writing implement that has a wide practicality and can obtain good writing performance by using a specific compound that chemically removes the gas in the ink described above, and a built-in ink composition. It is to provide a writing implement that has been developed.

[0004]

According to the present invention, there is provided an aqueous ink composition comprising at least a coloring agent, water, a water-soluble organic solvent, and a shear-thinning agent, comprising a sulfite, a sulfoxylate, and a dithionate. And a water-based ink composition for writing implements comprising one or more compounds selected from thiosulfates. Furthermore, one or two or more compounds selected from the above-mentioned sulfites, sulfoxylates, dithionites, and thiosulfates are used in the ink composition in an amount of 0.01 to 5%.
% By weight, 100r by E-type viscometer
Ink viscosity at pm 20-200mPa · s
(25 ° C.) and a shear thinning index of 0.1 to
0.8 is required. Further, a writing tool in which the ink composition is filled in a writing tool of a type in which an ink backflow preventing body that follows the ink consumption is arranged is required.

The inventor of the present invention has found that among the above-mentioned compounds which chemically remove the gas in the ink exhibiting the shear thinning property, there is little effect on various additives, and a sufficient gas removing function can be obtained by adding a small amount of the compound. As a result of intensive studies on compounds that exhibit and exhibit the above function permanently, sulfites, sulfoxylates, dithionites, compounds selected from thiosulfates maintain good writing performance and are remarkable in the long term. It has been found that it exhibits an excellent gas removal function.

The sulfites, sulfoxylates, dithionites, and thiosulfates are mainly used as reducing agents, and exhibit good oxygen absorbing ability when added to an ink composition. Therefore, it is presumed that gas containing oxygen in the ink is prevented from collecting and forming bubbles. Examples of the salt of the compound include alkali metal salts such as Na and K;
Examples thereof include ammonium salts and alkanolamine salts such as monoethanolamine, diethanolamine, and triethanolamine. Specific examples of the sulfite include sodium sulfite, sodium bisulfite, potassium sulfite, potassium bisulfite, ammonium sulfite, and the like. Preferably, sodium sulfite is used.
Examples of the sulfoxylate include sodium sulfoxylate, sodium hydrogen sulfoxylate, potassium sulfoxylate, potassium hydrogen sulfoxylate, ammonium sulfoxylate, and the like, and preferably sodium sulfoxylate is used. Examples of the dithionite include sodium dithionite, potassium dithionite, and ammonium dithionite, and sodium dithionite is preferably used. Examples of the thiosulfate include sodium thiosulfate, sodium thiosulfate, potassium thiosulfate, potassium hydrogen thiosulfate, and ammonium thiosulfate.

The above-mentioned compound is used in the ink composition in an amount of 0.01%.
To 5% by weight, preferably 0.05 to 1% by weight. If the content is less than 0.01% by weight, it is difficult to obtain the desired effect of suppressing the generation of bubbles. If the content is less than about 5% by weight, the desired effect is sufficiently obtained, so that 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 are shown below. As the dye, an acid dye, a basic dye, a direct dye, or the like can be used. As the acid dye, neucoccin (C.I.
I. 16255), tartrazine (CI. 1914)
0), Acid Blue Black 10B (CI.204
70), Guinea Green (CI. 42085), Brilliant Blue FCF (CI. 42090), Acid Violet 6B (CI. 42640), Soluble Blue (CI. 42755), Naphthalene Green (C. .I.44025), eosin (CI.4538)
0), Phloxine (CI. 45410), Erythrosin (CI. 45430), Nigrosine (CI. 50)
420), acid flavin (CI. 56205) and the like.

As the basic dye, chrysoidin (C.I.
I. 11270), methyl violet FN (CI.
42535), crystal violet (C.I.42)
555), malachite green (CI. 4200)
0), Victoria Blue FB (CI.44045),
Rhodamine B (CI. 45170), Acridine Orange NS (CI. 46005), Methylene Blue B
(C.I. 52015) and the like are used.

As a direct dye, Congo Red (C.I.
I. 22120), Direct Sky Blue 5B (C.I.
I. 24400), Violet BB (CI. 279)
05), direct deep black EX (CI.3
0235), Kayalas Black G Conch (CI.35
225), Direct Fast Black G (CI.3)
5255), phthalocyanine blue (CI. 7418)
0) etc. are used.

As the pigment, in addition to inorganic pigments such as carbon black and ultramarine blue, and organic pigments such as copper phthalocyanine blue and benzidine yellow, finely and stably dispersed in an aqueous medium using a surfactant or a resin in advance. Water-dispersed pigment products and the like. I. Pigment
Blue 15: 3B [Product name: Sandy Suppe]
r Blue GLL, pigment content 24%, Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Red 146 [Product name: S
andy Super Pink FBL, pigment content 2
1.5%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Yellow 81 [Product name:
TC YellowFG, pigment content: about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.] I. Pigment Red 220/166 [product name: TC Red FG, pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.] and the like. In addition, 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 include polystyrene, acrylic resin, maleic resin, gum arabic, cellulose, dextran, casein, and the like, and derivatives thereof, and copolymers of the above resins. As the fluorescent pigment, a fluorescent pigment in the form of fine particles of a synthetic resin in which various fluorescent dyes are made into a solid solution in a resin matrix can be used.
Also, white pigments such as titanium dioxide, metal powders such as aluminum, pearl pigments, gold and silver metallic pigments, luminous pigments, fragrances and fragrance capsule pigments can be used. The pigments may be used alone or in combination of two or more, and 1 to 25% by weight in the ink composition.
Preferably, it is used in the range of 2 to 15% by weight.

As the water-soluble organic solvent, a conventional general-purpose solvent compatible with water is used. Ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, Thiodiethylene glycol, hexylene glycol, 1,3-butanediol, neoprene (registered trademark)
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 monoethyl ether, 2-pyrrolidone , N-methyl-2-pyrrolidone and the like. The water-soluble organic solvent may be used alone or in combination of two or more, and is used in an amount of 2 to 60% by weight, preferably 5 to 35% by weight.

In addition, if necessary, a pH adjuster, a preservative or a fungicide can be added. Examples of the pH adjuster include inorganic 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 fungicide include sodium salt of carboxylate, 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, it is also possible to add a fluorine surfactant for improving the permeability of the solvent, a nonionic, anionic or cationic surfactant, and an antifoaming agent such as dimethylpolysiloxane.

One or more water-soluble resins such as an alkyd resin, an acrylic resin, a styrene-maleic acid copolymer, a cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin are added in a range that does not hinder the drying resistance. Alternatively, one or more humectants such as urea, nonionic surfactant, sorbite, mannitol, sucrose, glucose, reduced starch hydrolyzate, sodium pyrophosphate and the like can be added.

The shear thinning of the ink composition of the present invention means that the ink composition has a property of being extremely high in viscosity and hard to flow in a static state or a low stress, and has a rheological property of exhibiting a good viscosity due to a low viscosity when the stress increases. Which means liquidity also called thixotropy or pseudoplasticity. Therefore, under the high shear stress during writing, the ink composition temporarily breaks the three-dimensional structure and the viscosity of the ink decreases, and the ink at the writing tip becomes a low-viscosity ink suitable for writing and is transferred to the paper surface. You. At the time of non-writing, the viscosity of the ink is increased, so that leakage of the ink, separation of the ink, and backflow of the ink can be prevented. In addition, the physical properties of the ink can be kept stable over time. In particular, the ballpoint pen holding the ball at the tip of the writing, under high shear stress during writing, the ink near the ball becomes low viscosity suitable for writing,
It is necessary to have ink properties that can be transferred to the paper surface by moving the gap between the ball and the ball house by capillary force, and when not writing, the viscosity of all inks, including near the ball, increases, preventing ink leakage. And it is necessary to prevent ink separation and backflow, and the ink viscosity at 100 rpm by an E-type viscometer is 20 to 200 mPa.
S (25 ° C.) and a shear thinning index of 0.1
Ink compositions exhibiting -0.8 are preferred.

As the shear-thinning agent, substances soluble or dispersible in water are effective, and 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, hydroxyethylcellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000, and glycomannan, which are mainly composed of alkyl esters of methacrylic acid; Thickening polysaccharides having gelling ability extracted from seaweeds such as agar and carrageenin, benzylidene sorbitol and benzylidene xylitol or derivatives thereof, a 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 HLB value of phenyl ether, fatty acid amide, etc. is 8
To 12 nonionic surfactants, salts of dialkyl or dialkenyl sulfosuccinic acid, and the like, and these can be used alone or in combination. Further, N-alkyl-
A mixture of 2-pyrrolidone and an anionic surfactant, and a mixture of polyvinyl alcohol and an acrylic resin can also be used. The shear thinning agent can be used in an amount of 0.1 to 20% by weight in the ink composition.

In addition, a rust preventive, a lubricant and the like can be added as required. Examples of the rust preventive include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, ethylenediaminetetraacetate, saponin, dialkylthiourea and the like. 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.

In addition, as the lubricant preferably used,
Phosphate-based surfactants described in the following general formula or Japanese Patent Publication No. 1-1508 are exemplified.

[0019]

Embedded image (Wherein, R ₁ represents an alkyl group or alkenyl group of 8 to 18,
Alternatively, a phenyl group, an alkylphenyl group, R ₂
It is OH, OM, R-O- ( CH 2 CH 2 O) shows the _n,
M represents an alkali metal, an amine, or an alkanolamine, and n represents 1 to 30. )

The aqueous ink composition for a writing instrument of the present invention is filled into a marking pen or a ball-point pen having a fiber tip, a felt tip, a plastic tip, and a ball-point pen tip attached to a writing tip.

The structure and shape of the ball-point pen itself are not particularly limited, and conventional ball-point pens can be used. For example, the ball-point pen has an ink container filled with an ink composition in a shaft cylinder. Is a ball-point pen that communicates with a chip having a ball attached to the tip, and a liquid stopper for preventing backflow is in close contact with the end surface of the ink.

The ballpoint pen tip will be described in more detail. A tip holding a ball in a ball holding portion in which the vicinity of the tip of a metal pipe is pressed and deformed inward from the outer surface, or a metal material such as a drill is used. A chip holding a ball in a ball holding portion formed by cutting by the above or a ball held by a chip formed by cutting a metal pipe or a metal material is urged forward by a spring body. Can be applied. Also, the ball is
0.1% of cemented carbide, stainless steel, ruby, ceramic, etc.
Those having a diameter of about 3 to 1.2 mm can be applied.

For the ink containing tube for containing the ink composition, for example, a molded article made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate or the like is suitably used in terms of low ink evaporation and productivity. The ink container preferably has an inner diameter of 2.5 to 10 mm. Further, by using a transparent, colored transparent or translucent molded body as the ink storage tube, the ink color, the remaining amount of the ink 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 connection member. In addition, the ink storage tube has a form of refill,
The refill may be housed in the barrel, or the barrel itself with the tip attached to the tip as an ink container.
The shaft cylinder may be directly filled with ink.

The back end of the ink composition contained in the ink containing tube is filled with an ink backflow preventer. As the ink backflow preventive, any liquid or solid can be used.Examples of the liquid ink backflow preventive include non-volatile media such as polybutene and silicone oil.
If desired, silica, aluminum silicate and the like can be added to the medium. In addition, examples of the solid ink backflow preventer include a resin molded product. Further, the liquid and solid ink backflow preventers may be used in combination.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous ink composition for a writing instrument of the present invention comprises a dye or pigment (pigment dispersion), a sulfite, a sulfoxylate, a dithionite in a medium comprising water and a water-soluble organic solvent. , A compound selected from thiosulfates, when additives are blended, the additives are appropriately added, heated and stirred as necessary, and prepared by dissolving and dispersing, a ballpoint pen, a felt-tip pen, a felt-tip pen, It is used by filling into a writing implement such as a brush pen.

[0026]

EXAMPLES The ink compositions of the present invention and comparative examples, and the viscosities of the inks at 25 ° C. at 1 rpm, 10 rpm, and 100 rpm by an EM-type rotational viscometer and the shear thinning index are shown below. The numbers in the composition indicate parts by weight.

Example 1 Blue pigment 25.0 [manufactured by Sanyo Dyeing Co., Ltd., trade name: SS BLUE GLL] ethylene glycol 15.0 succinoglycan 0.3 (constituent monosaccharide is organic acid-modified hetero of glucose and galactose) Polysaccharide) 1,2-benzisothiazolin-3-one 0.1 [manufactured by Zeneca Corporation, trade name: Proxel XL-2] Sodium sulfite 0.3 water 59.3 total 100.0

The above composition is mixed, stirred at room temperature with a disper for 3 hours, and filtered to obtain a water-based ink composition for writing implements. The ink composition at 25 ° C.
The viscosity at 1 rpm by an EM-type rotational viscometer was 1,400 mPa · s, the viscosity at 10 rpm was 200 mPa · s, the viscosity at 100 rpm was 40 mPa · s, and the shear thinning index was 0.22.
It was 8.

Example 2 Pink Pigment 40.0 [Product name: Lumicoll NKW-2117, manufactured by Nippon Fluorescent Chemical Co., Ltd.] Glycerin 15.0 Succinoglycan 0.3 (Organic acid whose constituent monosaccharide is glucose and galactose) Modified heteropolysaccharide) Sodium omadin 0.3 [Permachem Co., Ltd., trade name: Topside 280] Sodium sulfoxylate 0.3 Water 44.1 Total 100.0 After stirring for 3 hours and filtering, an aqueous ink composition for writing implements is obtained. The EM of the ink composition at 25 ° C.
The viscosity at 1 rpm by a rotary viscometer is 1200 m
Pa · s and the viscosity at 10 rpm is 144 mP
a · s and the viscosity at 100 rpm is 42 mP.
a · s, and the shear thinning index was 0.272.

Example 3 Aluminum paste 7.0 [Toyo Aluminum Co., Ltd., trade name: 96-2104] Glycerin 15.0 Succinoglycan 0.3 (Constituent monosaccharide is organic acid-modified heteropolysaccharide of glucose and galactose) Body) Sodium omadine 0.3 [Permachem Co., Ltd., trade name: Topside 280] EDTA amine salt 1.0 [Cyrest Co., Ltd., trade name: Cyrest M-50] α-cyclodextrin 0 [manufactured by Saltwater Port Sugar Co., Ltd., trade name: Dexipearl K-100] Sodium bisulfite 0.3 water 73.1 total 100.0

The above-mentioned composition is mixed, stirred at room temperature with a disper for 3 hours, and filtered to obtain a water-based ink composition for writing implements. The ink composition at 25 ° C.
The viscosity at 1 rpm by an EM-type rotational viscometer was 1,400 mPa · s, the viscosity at 10 rpm was 205 mPa · s, the viscosity at 100 rpm was 44 mPa · s, and the shear thinning index was 0.249.
Met.

Example 4 Red Acid Dye 5.0 [manufactured by Eisen Co., Ltd., C.I. I. Acid Red 92, C.I. I. 45410] Diethylene glycol 15.0 Xanthan gum 0.3 Lithium carbonate 0.3 Sodium dithionite 0.2 Water 79.2 Total 100.0

The above composition is mixed, stirred at room temperature with a disper for 3 hours, and filtered to obtain a water-based ink composition for writing implements. The viscosity of the ink composition at 1 rpm measured by an EM-type rotational viscometer was 1300 mP.
a · s and the viscosity at 10 rpm is 190 mPa
S and the viscosity at 100 rpm is 41 mPa
S and the shear thinning index was 0.249.

Comparative Example 1 An aqueous ink composition for a writing implement was obtained in the same manner as in Example 1, except that the sodium sulfite used in Example 1 was changed to water.

Comparative Example 2 An aqueous ink composition for a writing implement was obtained in the same manner as in Example 2, except that the sodium sulfoxylate used in Example 2 was changed to water.

Comparative Example 3 An aqueous ink composition for a writing implement was obtained in the same manner as in Example 3, except that the sodium bisulfite used was changed to water.

Comparative Example 4 A water-based ink composition for a writing instrument was obtained in the same manner as in Example 4, except that the sodium dithionite was changed to water.

According to the above-mentioned ink preparation method, inks of Examples and Comparative Examples were prepared, and a stainless steel tip holding a ball having a diameter of 0.5 mm was filled in a ballpoint pen refill fitted to one end of a polypropylene pipe. Further, after filling the ink backflow preventive body in close contact with the rear end face of the ink, the ballpoint pen refill was incorporated into a shaft cylinder to obtain a ballpoint pen.

The initial ballpoint pens obtained as described above and the ballpoint pens left at 50 ° C. for 60 days were visually inspected for the presence or absence of air bubbles in the ink storage tube and the state of the handwriting by a writing test. The results are shown below.

[0040]

[Table 1]

The criteria in the above table are as follows. Handwriting state ：: Good handwriting is obtained. ×: Scatter is seen in the handwriting.

[0042]

According to the ink composition of the present invention, since a compound selected from a sulfite, a sulfoxylate, a dithionite, and a thiosulfate is blended, air bubbles can be removed. In a writing instrument using, no air bubbles are generated over time, ink is smoothly led to the writing tip, stable writing performance can be maintained, and good handwriting can be continuously obtained.

Claims (4)

[Claims] 1. An aqueous ink composition comprising at least a colorant, water, a water-soluble organic solvent, and a shear-thinning agent, wherein the aqueous ink composition is selected from sulfites, sulfoxylates, dithionites, and thiosulfates. Alternatively, a water-based ink composition for a writing instrument comprising two or more compounds. 2. An ink composition comprising 0.01 to 5% by weight of one or more compounds selected from the group consisting of sulfites, sulfoxylates, dithionites, and thiosulfates. A water-based ink composition for a writing instrument. 3. The ink viscosity of 100 to 200 mPa · s (25 ° C.) at 100 rpm by an E-type viscometer and a shear thinning index of 0.1 to 0.8. A water-based ink composition for a writing instrument. 4. A writing implement of the type in which an ink backflow preventive that follows the ink consumption is arranged, wherein the writing implement is filled with the ink composition according to any one of claims 1 to 3.