JPH11293175A - Aqueous ink for ball point pen, and ball point pen using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous ink capable of scientifically removing gas in ink and providing good writing performance by making the ink include a specific N-vinyl-2-pyrrolidone oligomer. SOLUTION: This aqueous ink comprises (A) a coloring agent and water, (B) a water-soluble organic solvent, (C) an agent for imparting low viscosity under shearing stress and (D) preferably 1-20 wt.% N-vinyl-2-pyrrolidone oligomer represented by the formula [(n) is 2-20]. Furthermore, the compounding ratio of each component in the ink composition is preferably shown as follows: the component A: 1-25 wt.%; the component B (e.g. ethanol): 10-80 wt.%; the component C (e.g. xanthan gum): 1-30 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-based ink for a ball-point pen and a ball-point pen using the same. More specifically, the present invention relates to a water-based ink for a ball-point pen exhibiting shear thinning and a ball-point pen filled with the ink.

[0002]

2. Description of the Related Art A water-based ink composition for a ballpoint pen containing a shear-thinning agent such as a high molecular weight polysaccharide has been disclosed as a water-based ink for a ballpoint pen having a shear-thinning property (Japanese Patent Application Laid-Open No. 4-214782). . This type of ink has a high viscosity when left unattended with no shear stress, is stably held in the ballpoint pen mechanism, and during writing, the ink near the ball is subjected to the high shearing force of the high-speed rotating ball. Is reduced in viscosity, and as a result, the ink is ejected from the gap between the ball and the ball accommodating portion and is transferred to the paper surface.
Further, the ink transferred to the paper surface is released from the shearing force and becomes high in viscosity again, so that the blur of the handwriting which is a drawback of the conventional low-viscosity aqueous ballpoint pen ink does not occur. Furthermore,
Since the ink does not leak, unlike the low-viscosity water-based ballpoint pen, and does not require a flow rate adjusting member (pen core) for adjusting the ink flow rate or a valve mechanism depending on the above-mentioned shear thinning viscosity, it is simple. A ballpoint pen with a structure is obtained.

[0003]

The above-described conventional water-based ink for shear-thinning ballpoint pens has a simple structure, but requires special consideration in the preparation and filling of the ink. As an example, it is possible to prevent the solvent in the ink from evaporating to the rear end face of the ink, or to prevent the ink from flowing backward when the writing tip is in an upright state (erect state), and to consume ink at the time of writing. Accordingly, it is necessary to fill an ink backflow prevention body (liquid stopper) that follows. As a result, since the ink is present in an airtight space that is cut off from the outside air, if gas is mixed in the ink,
With the passage of time, gas collects and bubbles are generated, and air bubbles are present at the writing tip and writing becomes impossible, or when the writing tip is left downward (inverted state), bubbles are generated between the ink and the ink backflow prevention body. And adversely affect ink ejection, for example, the backflow of ink is likely to occur and writing becomes impossible. In order to solve the above-mentioned problem, defoaming treatment for mechanically removing gas in the ink is mainly performed, but it is difficult to perform sufficient defoaming by this method alone, and gas remains in the ink. There is. Also, pigments, metal powders, titanium oxide, etc.
When an insoluble colorant is used, a problem such as uneven distribution of the colorant in the ink storage tube occurs when processing such as centrifugal defoaming is performed. An object of the present invention is to provide a water-based ink for a ball-point pen and a ball-point pen using the same, which can obtain good writing performance by chemically removing gas in the ink to solve the above-mentioned problem. .

[0004]

SUMMARY OF THE INVENTION The present invention provides a colorant, water,
A requirement is a water-based ink for a ballpoint pen, comprising a water-soluble organic solvent, a shear-thinning agent, and an oligomer of N-vinyl-2-pyrrolidone represented by the following general formula. General formula

Embedded image (n represents an integer of 2 to 20) Further, a water-based ink for a ballpoint pen containing 1 to 20% by weight of the oligomer of N-vinyl-2-pyrrolidone is required. Further, a ball-point pen is required in which an aqueous ink for a ball-point pen and an ink backflow prevention body that follows the ink as it is consumed are stored at the rear end of the aqueous ink in an ink storage tube.

[0005] The above-mentioned oligomer of N-vinyl-2-pyrrolidone exhibits oxygen absorbing ability when added to an aqueous ink. Therefore, it is presumed that gas containing oxygen in the ink is prevented from collecting and forming bubbles. or,
As the oligomer of N-vinyl-2-pyrrolidone represented by the general formula, one having a degree of polymerization (n) of 2 to 20, preferably 2 to 10, and more preferably 2 to 6, N-vinyl-2 having different degrees of polymerization in the ink
-A plurality of oligomers of pyrrolidone may be added. still,
It is difficult for N-vinyl-2-pyrrolidone monomer to exhibit oxygen-absorbing ability, and when the degree of polymerization of the oligomer exceeds 20, although it has oxygen-absorbing ability, the viscosity becomes high and ink ejection becomes poor. Adversely affect writing performance.

The above-mentioned oligomer of N-vinyl-2-pyrrolidone can be added to the ink composition in an amount of 1 to 20% by weight, preferably 1 to 10% by weight. If the content is less than 1% by weight, it is difficult to obtain the expected bubble generation suppressing effect.
If the content is about 20% by weight or less, the desired effect can be sufficiently obtained, so that further addition is not required.

As the colorant, all dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used.
Specific examples will be described below. As the dye, an acid dye, a basic dye, a direct dye, or the like can be used. As the acid dye, Neucoccin (CI.16)
255), Tartrazine (CI. 19140), Acid Blue Black 10B (CI. 20470), Guinea Green (CI. 42085), Brilliant Blue FCF (CI. 42090), Acid Violet 6B (C. I. 42535), Soluble Blue (C.I. 42755), Naphthalene Green (C.I.
I. 44025), eosin (CI. 45380),
Phloxine (CI. 45410), Erythrosin (CI. 45430), Nigrosine (CI. 504)
20), acid flavin (CI. 56205) and the like.

[0008] 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 (CI. 22120) Direct Sky Blue 5B (CI. 24400) Violet BB (CI. 27905) Direct Deep Black EX (CI. 3023)
5) Kayalas Black G Conch (CI. 35225) Direct Fast Black G (CI. 35255) Phthalocyanine blue (CI. 74180) or the like is 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 that is already finely and stably dispersed in an aqueous medium using a surfactant. Dispersed pigment products and the like are used. I. Pigment 15: 3B [trade name: S.I.
S. Blue GLL, pigment content 24%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Red 146 [Product name:
S. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Yellow 81 [trade name: TC Yellow FG, pigment content: about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.] C.I. I. Pigment Red 220/166 [trade name: TC Red FG, pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.] and the like. 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. Other examples include pearl pigments, gold and silver metallic pigments, luminous pigments, white pigments such as titanium dioxide, metal powders such as aluminum, and fragrance or fragrance capsule pigments.

The colorants may be used alone or in admixture of two or more, and are used in an amount of 1 to 25% by weight, preferably 2 to 15% by weight in the ink composition.

As the solvent, in addition to water, a water-soluble organic solvent which is a conventional and generally water-soluble solvent is used. Ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine Ethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol,
Examples thereof include butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone. still,
The water is used in the range of 10 to 80% by weight, preferably 20 to 75% by weight. The water-soluble organic solvents may be used alone or in combination of two or more, and are used in an amount of 2 to 60% by weight, preferably 5 to 35% by weight.

As the shear-thinning agent, water-soluble or dispersible substances 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; Carbohydrates having a gelling ability extracted from seaweeds such as agar and carrageenan, benzylidene sorbitol and benzylidene xylitol or derivatives thereof, crosslinkable acrylic acid polymer, inorganic fine particles, H
Nonionic surfactants having an LB value of 8 to 12 can be exemplified, and can be used alone or as a mixture.

As the water-soluble resin, alkyd resin,
One or more of acrylic resin, styrene-maleic acid copolymer, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, dextrin and the like can be used for fixing to paper and imparting viscosity. It is used in the range of 30% by weight.

In addition, if necessary, inorganic salts such as sodium carbonate, sodium phosphate and sodium acetate, pH adjusters such as organic basic compounds such as water-soluble amine compounds, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, Rust inhibitors such as diisopropylammonium nitrite and saponin;
-Sodium salt of benzthiazolin 3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-
Preservative or fungicide such as tetrachloro-4- (methylsulfonyl) pyridine, metal soap, polyalkylene glycol, fatty acid ester, ethylene oxide addition type cation activator, phosphoric acid activator, thiocarbamate, dimethyldithiocarbamic acid Lubricant such as salt, urea, nonionic surfactant, sorbit, mannitol, sucrose, glucose, reduced starch hydrolyzate, wetting agent such as sodium pyrophosphate, defoamer, dispersant, ink permeability A fluorine-based surfactant or a nonionic surfactant which is improved may be used.

The structure of the writing tip (tip) of the ball-point pen filled with the water-based ink for a ball-point pen is generally a general-purpose mechanism effective, and the vicinity of the tip of the metal pipe is deformed by pressing inward from the outer surface. A chip holding a ball in a ball holding portion, or a chip holding a ball in a ball holding portion formed by cutting a metal material with a drill or the like, or a metal pipe or metal material In this case, a ball held by a chip formed by the above cutting process and urged forward by a spring body can be applied. Further, the ball having a diameter of about 0.3 to 1.2 mm, such as a cemented carbide, stainless steel, ruby, or ceramic, can be used.

[0017] In the ink containing tube for containing the ink and the ink backflow preventive, for example, a molded article made of a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate is preferably used in view of low ink evaporation and productivity. Used. In addition, the ink storage tube is 2.5 to 10
Those having an inner diameter of mm are preferably used. 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 may be one in which the refill is stored in a shaft cylinder as a form of a ballpoint pen refill, or the shaft cylinder itself having a tip attached to a tip as an ink container may be inserted in the shaft cylinder. The ink may be directly filled. The inner diameter of the refill housed in the barrel is:
Those having a diameter of 2.5 to 5 mm are preferably used, and those having a diameter of 4 to 10 mm are preferably used as the inner diameter of a shaft cylinder for directly storing ink.

Examples of the ink backflow preventer include non-volatile media such as polybutene and silicone oil. If desired, silica, aluminum silicate and the like can be added to the medium.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous ink for a ballpoint pen of the present invention is prepared according to a usual method for preparing a ballpoint pen ink.
It is practically used in a so-called direct liquid state in which a ballpoint pen tip is directly filled into an ink storage tube having a writing tip.

[0020]

EXAMPLES The ink compositions of the present invention and comparative examples are shown below. In addition, the numerical value which shows the combination in a table | surface shows a weight%.

[0021]

[Table 1]

[0022]

[Table 2]

The contents of the raw materials in the table will be described along the note numbers. (1) Phloxine [C.I. I. Aci
d Red 92, C.I. I. 45410] (2) Water Yellow 6C [Orient Co., Ltd.
C. I. Acid Yellow 42S] (3) FUJI LM Orange 21 [manufactured by Fuji Dye Co., Ltd., fluorescent pigment dispersion, solid content 50%] (4) Sundai Super Black C [Sanyo Dye Co., Ltd.]
(5) Organic acid-modified heteropolysaccharide of glucose and galactose (6) hexaglycerin monooleate [Nikko Chemicals Co., Ltd., trade name: Hexaglyn 1- 0] (7) N-vinyl-2-pyrrolidone oligomer (manufactured by Sanken Chemical, n = 2 to 6) (8) Poly-N-vinyl-2-pyrrolidone (manufactured by BASF, molecular weight 38,000)

The formulations shown in Examples and Comparative Examples were heated at 60 ° C.
After stirring with a mixer for 1 hour while heating at, the mixture is cooled and filtered to obtain a water-based ink for a ballpoint pen.

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 0.4 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.

After the ballpoint pen obtained as described above is allowed to stand at 25 ° C. for 10 days and at 40 ° C. for 7 days, the number of air bubbles in the ink container tube and the presence or absence of air bubbles are visually observed as compared with the initial stage. did. In addition, the said ball-point pen was produced 5 each. The results are shown below.

[0027]

[Table 3]

The judgment results in the above table are as follows. ：: Air bubbles in the ink completely disappeared, and no new air bubbles were generated. ：: Air bubbles in the ink are reduced, and no new air bubbles are generated. Δ: No change from initial stage. X: Air bubbles increase.

The initial ballpoint pen obtained as described above was used to write on the paper, and the ink consumption and the handwriting were examined visually. The results are shown below.

[0030]

[Table 4]

[0031]

[Table 5]

In the measurement of the ink consumption in the table, the ink consumption was calculated after writing 500 m with an automatic writing tester. Here, the writing conditions in the automatic writing test machine are a writing speed of 4 m / min, a writing load of 100 g, and a writing angle of 70 °. The judgment results for handwriting are as follows. ：: There is no blurring or broken lines. Δ: Slight blurring or line breakage occurs. ▲: Bleeding occurs. ×: Blurring or breakage of the line occurs. The measurement results were obtained by measuring each of five ballpoint pens created and calculating the average value.

[0033]

The water-based ink for a ball-point pen of the present invention comprises N-
Since the vinyl-2-pyrrolidone oligomer is compounded, generation of bubbles is suppressed. Therefore, in a ball-point pen using the ink, bubbles are hardly generated with the passage of time, the ink is smoothly led out to the tip of writing, stable writing performance can be maintained, and good handwriting is continuously obtained. Can be

Claims (3)

[Claims] 1. A colorant, water, a water-soluble organic solvent, a shear-thinning agent, and N-vinyl-2- represented by the following general formula:
A water-based ink for ballpoint pens comprising an oligomer of pyrrolidone. General formula (N represents an integer of 2 to 20) 2. The water-based ink for a ball-point pen according to claim 1, comprising 1 to 20% by weight of the oligomer of N-vinyl-2-pyrrolidone. 3. A ball-point pen in which an aqueous ink for a ball-point pen and an ink backflow preventive that follows the ink at the rear end thereof are accommodated in an ink storage tube.