JP2002129084A - Water based ink composition for writing implement and writing implement with built-in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based ink composition for writing implement in which good handwritings are obtained, while preventing bubbles to generate in ink, and to provide a writing implement with built-in the same. SOLUTION: The water-based ink composition composed of a coloring agent, water, water soluble organic solvent and thiourea dioxide shown by the formula (1) and/or formamidinesulphinic acid shown by the formula (2), and the writing implement with built-in the same are 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 filled with an ink backflow preventive that follows the ink consumption using the composition.

[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 an ink having a shear-thinning property among water-based inks (Japanese Patent Laid-Open Publication No. Hei 4-1992). No. 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. Furthermore, a writing instrument having a simple structure can be obtained because ink leakage does not occur due to the above-mentioned shear thinning and a flow rate adjusting member (pen core) for adjusting the ink flow rate is not required.
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 prevention body (liquid tap) is filled,
Since the ink is present in an airtight space that is cut off from the outside air, if gas is mixed in the ink, the gas collects with the passage of time and bubbles are generated, which has an adverse effect on ink output during writing and also has a negative effect on writing. This is because writing may not be possible if bubbles exist at the tip. Separately from this, as the writing implement of the type in which the ink backflow prevention body is filled, by providing a valve mechanism near the writing tip, it is possible to fill the aqueous ink composition that does not show shear thinning, In the same manner as described above, the presence of air bubbles adversely affects writing performance. 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.
Further, α-tocopherol is insoluble in water and is separated over time, making it difficult to permanently exhibit a gas removing function. In addition, the catechins are limited in a coloring agent to be applied,
Although good gas removal is possible without causing a problem such as the gas removal function disappearing in a short period of time, catechins are low in purity because of natural extract, and show reducing property. Only a small number of functional groups remove gas, and a large amount must be added to obtain the 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 colorant, water and a water-soluble organic solvent, wherein the thiourea dioxide is represented by the following general formula (1) and / or A requirement is a water-based ink composition for writing implements comprising formamidinesulfinic acid represented by the formula (2). Further, the thiourea dioxide and / or formamidine sulfinic acid may be added to the ink composition in an amount of 0.01 to 0.01%.
-5% by weight, the pH of the ink composition is 7 or less, the composition contains a shear-thinning agent,
It is required that the ink viscosity at 100 rpm by a mold rotational viscometer shows 20 to 200 mPa · s (25 ° C.) and the shear thinning index shows 0.1 to 0.8. 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 shown that among the above-mentioned compounds for chemically removing gas in ink, there is little effect on various additives, and the compound has a sufficient gas removing function with a small amount of addition. As a result of intensive studies on compounds to be permanently expressed, thiourea dioxide represented by the general formula (1) or formamidine sulfinic acid represented by the general formula (2) is remarkable in the long term while maintaining good writing performance. It has been found that it exhibits an excellent gas removal function.

[0006] The thiourea dioxide is gradually decomposed in the ink composition to form reducing formamidine sulfinic acid, and exhibits good oxygen absorbing ability in the ink composition. Therefore, it is presumed that gas containing oxygen in the ink is prevented from collecting and forming bubbles. The thiourea dioxide is a compound represented by the following general formula (1).

[0007]

Embedded image

Further, formamidine sulfinic acid represented by the following general formula (2) can be directly added.

[0009]

Embedded image

The above-mentioned formamidine sulfinic acid exhibits a strong reducing property in an acidic atmosphere. Therefore, when the pH of the ink composition is adjusted to 7 or less, it functions well as a compound having excellent oxygen absorbing ability.

The thiourea dioxide and / or formamidine sulfinic acid can be added in an amount of 0.01 to 5% by weight, preferably 0.05 to 1% by weight in the ink composition. 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 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 the 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, organic pigments such as copper phthalocyanine blue and benzidine yellow, etc., they are 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%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Red 146 [product name: Sandy Super Pink FBL, pigment content 21.5%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pig
ment Yellow 81 [Product name: TC Yellow
owFG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. 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 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 2 to 60% by weight, preferably 5 to 60% by weight.
It is used in the range of 35% by weight.

In addition, a preservative or a fungicide can be added as required. 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 as long as the drying resistance is not impaired. 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 term "shear-thinning viscosity" of an ink composition refers to a rheological property in which the ink composition has a property of being extremely viscous and hard to flow when it is in a static state or a low stress, and has a low viscosity when the stress increases, showing good flowability. Which means a liquid property also called thixotropy or pseudoplasticity. Therefore, the ink composition under high shear stress at the time of writing, the three-dimensional structure is temporarily destroyed, the viscosity of the ink is reduced, the ink at the writing tip becomes a low-viscosity ink suitable for writing,
Transferred to paper. 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, in a ballpoint pen that holds a ball at the tip of writing, under high shear stress during writing, the ink near the ball has low viscosity suitable for writing, and moves through the gap between the ball and the ball house by capillary force, and It is necessary to have the characteristics of the ink transferred to the ink, and when not writing, the viscosity of all the ink, including the vicinity of the ball, increases, and it is necessary to prevent the leakage of the ink, the separation of the ink, and the backflow. 100 rpm by E-type viscometer
m is 20 to 200 mPa · s (25
C.), and an ink composition having a shear thinning index of 0.1 to 0.8.

As the shear-thinning agent, a substance soluble or dispersible in water is 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 containing glycomethannan as main components, glycomannan, 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 (3) or JP-B-1-1508 are mentioned.

[0023]

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 in a marking pen or a ball-point pen having a fiber tip, a felt tip, a plastic tip, and a ballpoint 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, a 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 ball-point 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 such as a drill 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 stored in the ink storage 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.

[0029]

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), thiourea dioxide or formamidine sulfinic acid, if necessary, in a medium comprising water and a water-soluble organic solvent. It is prepared by adding a shear-thinning agent and various additives, heating and stirring as needed, dissolving and dispersing, and filling and using a writing implement in the form of a ballpoint pen, felt-tip pen, felt-tip pen, brush pen, etc. Is done.

[0030]

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] Thiourea dioxide 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 an aqueous 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 Red Dye 5.0 [manufactured by Eisen Co., Ltd., trade name: Phloxine, C.I. I. Acid Red 92, C.I. I. 45410] Diethylene glycol 15.0 Xanthan gum 0.3 Lithium carbonate 0.3 Thiourea dioxide 0.1 Water 79.3 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 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.

Example 3 Pink fluorescent pigment 40.0 [manufactured by Nippon Fluorescent Chemical Co., Ltd., trade name: Lumicoll NKW-2117] glycerin 15.0 succinoglycan 0.3 (organic monosaccharide composed of glucose and galactose) Acid-modified heteropolysaccharide) Sodium omadine 0.3 [Product name: Topside 280, manufactured by Permachem Co., Ltd.] Thiourea dioxide 0.2 Water 44.2 Total 100.0 The resulting mixture is stirred for 3 hours and filtered to obtain a water-based ink composition for writing implements. 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 4 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] Formamidine sulfinic acid 0.2 Water 73.2 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 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.

Comparative Example 1 An aqueous ink composition for a writing implement was obtained in the same manner as in Example 1, except that thiourea dioxide 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 thiourea dioxide used in Example 2 was changed to water.

Comparative Example 3 An aqueous ink composition for a writing instrument was obtained in the same manner as in Example 3, except that thiourea dioxide used in Example 3 was replaced with 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 formamidine sulfinic acid 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 standing 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.

[0044]

[Table 1]

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

[0046]

The ink composition of the present invention contains thiourea dioxide and / or formamidine sulfinic acid, and therefore can remove air bubbles. Does not occur, ink is smoothly led out to the writing tip, stable writing performance can be maintained, and good handwriting can be continuously obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C350 GA03 GA04 NA10 NA11 4J039 AB01 AB02 AB04 AD06 AD09 AD10 AE07 BC06 BC07 BC12 BC20 BC36 BC37 BC44 BC50 BC54 BE01 BE03 BE04 BE05 BE12 BE16 BE22 BE23 BE30 BE33 CA03 CA06 EA48 GA26 GA27

Claims (6)

[Claims] 1. An aqueous ink composition comprising at least a colorant, water and a water-soluble organic solvent, wherein a thiourea dioxide represented by the following general formula (1) and / or a form represented by the following general formula (2) are provided. An aqueous ink composition for a writing instrument comprising amidine sulfinic acid. Embedded image Embedded image 2. The aqueous ink composition for a writing instrument according to claim 1, wherein the thiourea dioxide and / or formamidine sulfinic acid is contained in the ink composition in an amount of 0.01 to 5% by weight. 3. The aqueous ink composition for a writing instrument according to claim 1, wherein the pH of the ink composition is 7 or less. 4. The method according to claim 1, further comprising a shear thinning agent.
4. A water-based ink composition for a writing instrument according to any one of items 3 to 3. 5. The writing implement according to claim 4, wherein the ink viscosity at 100 rpm by an E-type rotational viscometer shows 20 to 200 mPa · s (25 ° C.), and the shear thinning index shows 0.1 to 0.8. Water-based ink composition. 6. A writing implement of a type in which an ink backflow preventive that follows with the consumption of ink is disposed, wherein the writing implement is filled with the ink composition according to any one of claims 1 to 5.