JP2001011358A - Aqueous pigment ink for ball-point pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink capable of achieving the expected objective comprising the diminished wear or deformation of a ballpoint-receiving rest due to ballpoint rotation and the prevention of ballpoint sinking to the utmost, and causing no blur of characters written therewith even in their long distance by including a sucrose fatty acid ester. SOLUTION: This ink essentially comprises (A) water, (B) pref. 0.1-40 wt.% of a pigment, (C) pref. 0.1-5.0 wt.% of a crosslinked poly-N-vinylcarboxylic acid amide, and (D) pref. 0.1-5.0 wt.% of a sucrose fatty acid ester (e.g. sucrose stearic acid ester), and pref. contains (E) about 1-20 wt.% of a dispersant such as a polymeric dispersant like gum arabic and (F) about 5-40 wt.% of a solvent such as ethylene glycol.

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 used for a ball-point pen which has a ball-point pen tip for holding and holding a cemented carbide or ceramic ball as a writing member and discharges ink by rotation of the ball. More specifically, wear of the ball seat due to contact with the ball seat of the ballpoint pen tip while rotating the ball is suppressed as much as possible, and has a lubricating effect so that the ball is smoothly rotated. The present invention relates to an aqueous pigment ink for ballpoint pens that satisfies general requirements.

[0002]

2. Description of the Related Art Conventionally, ballpoint pens can provide relatively fine handwriting and, due to abrasion and crushing of the pentip even when used for a long period of time, compared to writing instruments having a fibrous nib or a resin nib. Widely used because the change in handwriting width is small.

In a writing mechanism of a ballpoint pen, ink attached to the ball surface is transferred to a writing surface such as paper as the ball rotates. Ballpoint pens are basically
It is necessary to satisfy the general requirements for ballpoint pens, in which an appropriate amount of ink is transferred to the surface to be written, and furthermore, blurring in handwriting and various problems such as ink leakage from the ballpoint tip of the ballpoint pen do not occur, Therefore, it is required to appropriately select additives and adjust physical properties.

In particular, ballpoint pens using water-based inks
Since the coefficient of friction of water, which is the main solvent, is larger than that of the oil-based solvent, relatively large frictional resistance is generated between the ball and the ball seat due to the rotation of the ball as compared with a ball-point pen using oil-based ink. When the distance is written, the ball seat is worn out, the ball sinks, and the protruding length of the ball protruding from the ballpoint pen tip is sometimes reduced. In the case of a ball with a shorter length, the tip of the ball-point pen tip (other than the ball) may be caught on the surface to be written, impeding a smooth writing feeling, or the ink circulation hole formed in the ball receiving seat may be removed by the ball. In some cases, resulting in insufficient ink discharge. In any case, a problem such as faint handwriting or heavy writing feeling occurs. Further, conventionally, a water-based ink obtained by adding a cross-linked poly N-vinyl carboxylic acid amide for the purpose of obtaining good print quality and preventing pigment aggregation over time and obtaining long-term stability is disclosed in JP-A-7-62287. Japanese Unexamined Patent Publication No. 9-1
No. 94785. The inks described in these publications also use an activator, a polymer-based pigment dispersant, a water-soluble resin, and the like in addition to the crosslinked poly N-vinylcarboxylic acid amide.

[0005]

SUMMARY OF THE INVENTION The above-mentioned crosslinked poly N
-Water-based inks using vinyl carboxylic acid amides have good initial writing feeling, but wear and deformation of the ball seat occur over long distance writing, and the writing feeling gradually worsens, and the handwriting becomes blurred etc. I will.

[0006]

SUMMARY OF THE INVENTION The present invention provides a water-based ink for a ballpoint pen containing a sucrose fatty acid ester, which comprises at least water, a pigment and a cross-linked poly-N-vinylcarboxylic acid amide. Is what you do.

The details will be described below. Cross-linked poly N-vinyl carboxylic acid amide is a water-soluble thickener that increases the viscosity of the entire ink and stabilizes dispersion by retaining the colorant, or prevents ink leakage by lowering the fluidity of the ink. In addition, various troubles, such as smoothing the rotation of the ball and improving the writing feeling, are less likely to occur. Examples of the cross-linked poly N-vinyl carboxylic acid amide include those in which the type of the carboxylic acid amide portion is acetamide or formamide, and the amount of the cross-linking agent added to the N-vinyl carboxylic acid amide monomer during production is 1.50%
0.45%, and the product is GX-2
05, NA-010 (the carboxylic acid amide moiety is acetamide, and the amount of the crosslinking agent added is 1.50%, manufactured by Showa Denko KK). Since the cross-linked poly N-vinyl carboxylic acid amide swells in a solvent or a dispersion medium and has elasticity, each effect is enhanced. 1.0 to 2.0% based on N-vinylcarboxylic acid amide monomer
It is preferable that Furthermore, since the elasticity to be retained is increased by swelling in a solvent or a dispersion medium, and each effect is enhanced, the crosslinked poly N-vinyl carboxylic acid amide is preferably in the form of fine particles. The amount of the cross-linked poly N-vinyl carboxylic acid amide used cannot be unconditionally determined in consideration of the interaction with other inks. However, if the amount is too small, the effect of suppressing the wear and deformation of the ball seat decreases. On the other hand, if the amount is too large, the ink becomes too thick and it becomes difficult to discharge the ink due to the rotation of the ball.

One or more sucrose fatty acid esters are selected and used to suppress wear and deformation of the ball seat. Examples include sucrose stearate, sucrose palmitate, sucrose myristate, sucrose oleate, sucrose laurate, sucrose behenate, sucrose erucate, and the like. Monoester, diester, triester and polyester can be used, respectively. However, as the degree of esterification increases, the solubility in water decreases, so that a larger amount of the solubilizer must be added. Specific examples of sucrose fatty acid esters include Ryoto Sugar Ester S-570,
S-770, S-970, S-1170, S-
1170S, S-1570, S-1670, S-
1670S, P-1570, P-1670, M-
1695, O-1570, OWA-1570, L
-595, L-1695 and LWA-1570 (all manufactured by Mitsubishi Chemical Foods Co., Ltd.). The amount of the sucrose fatty acid ester used is preferably 0.1 to 5.0% by weight. If the amount is small, no effect is obtained. If the amount is large, the sucrose fatty acid ester cannot be completely dissolved or no further effect is obtained.

Conventionally known pigments can be used as the pigment. Specific examples include Special Black 6,
S170, S610, 5, 5, 4, 4A, 55
0, 35, 250, 100, Printex 1
50T, U, V, 140U, 140V, 9
5, 90, 85, 80, 75, 55, 4
5, P, XE2, L6, L, 300, 3
# 0, # 3, # 35, # 25, # 200, #A, #G (all made by Degussa Japan KK), # 2400B, # 2
350, # 2300, # 2200B, # 1000, # 9
50, # 900, # 850, # MCF88, MA60
0, MA100, MA7, MA11, # 50, # 52,
# 45, # 44, # 40, # 33, # 32, # 30, C
F9, # 20B, # 4000B (Mitsubishi Chemical Industries, Ltd.), MONARCH 1300, 100, 1000, 900, 880, 800, 700,
MOGULL, REGAL 400R, 660R, 500R, 330R, 300R, 99R, ELF
TEX 8, 12 and BLACK PEARLS 20
00 (manufactured by Cabot Co. LTD, USA), Ra
ven 7000, 5750, 5250, 500
0, 3500, 2000, 1500, 125
5, 1250, 1200, 1170, 106
0, 1040, 1035, 1020, 100
0, 890H, 890, 850, 790, 7
80, 760, 500, 450, 430, 4
20, same 410, same 22, same 16, same 14, same 825o
il Beads, H20, C, Conducte
x 975, 900, SC (all above, Colombian
Carbon black, such as Carbon Japan Co., Ltd.), KA
-10, 10P, 15, 15, 20, 30, 35
60, 80, 90, KR-310, 380, 460, 480 (all manufactured by Titanium Industry Co., Ltd.), P2
5 (manufactured by Nippon Aerosil Co., Ltd.), etc., BS
-605, 607 (all manufactured by Toyo Aluminum Co., Ltd.), Bronze powder P-555, P-777 (all manufactured by Nakajima Metal Foil Industry Co., Ltd.), bronze powder 3L5, 3
Metal powder pigments such as L7 (above, manufactured by Fukuda Metal Foil Industry Co., Ltd.), and inorganic pigments such as black iron oxide, yellow iron oxide, red iron oxide, ultramarine, navy blue, cobalt blue, chrome green, chromium oxide, and the like. Hansa A-10G, 5G, 3
G, 4, GR, A, Benzidine Yellow, Permanent Yellow NCG, Tartrazine Lake, Quinoline Yellow, Sudahn 1, Permanent Orange, Indaslen Brilliant Orange GN, Permanent Brown F
G, para brown, permanent red 4R, fire red, brilliant carmine BS, pyrazolone red, lake red C, quinacridone red, brilliant carmine 6B, bordeaux 5B, thioindigo red,
Organic pigments such as Fast Violet B, Dioxane Violet, Alkaline Blue Lake, Phthalocyanine Blue, Indigo, Acid Green Lake, and Phthalocyanine Green. In addition, inorganic fluorescent pigments such as zinc sulfide, zinc silicate, cadmium zinc sulfate, calcium sulfide, strontium sulfide, and calcium tungstate may be used. The above-mentioned coloring agents can be used alone or in combination with others, and the amount of use varies depending on the color tone, etc. For this reason, the content is preferably 0.1 to 40% by weight based on the total amount of the aqueous ink.

Since the present ink uses a pigment, it is preferable to use a dispersant in combination. As the dispersant, a water-soluble resin or a water-soluble resin conventionally used generally, or a dispersant used as a pigment dispersant such as an anionic or nonionic surfactant can be used. As an example, as a polymer dispersant, gum arabic, natural gums such as tragacanth gum, glucosides such as saponin, methyl cellulose, carboxycellulose, cellulose derivatives such as hydroxymethyl cellulose, lignin sulfonate, natural polymers such as shellac, poly Anionic polymers such as acrylates, salts of styrene-acrylic acid copolymers, salts of vinylnaphthalene-maleic acid copolymers, sodium salts of β-naphthalenesulfonic acid formalin condensate, phosphates, etc., and polyvinyl chloride alcohol,
Examples include nonionic polymers such as polyethylene glycol. As surfactants, alkyl sulfates, polyoxyethylene alkyl ether sulfates, N-
Negatives such as acyl amino acids and salts thereof, N-acylmethyl taurine salts, polyoxyethylene alkyl ether acetates, alkyl sulfocarboxylates, α-olefin sulfonates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates. Nonionic surfactants such as ionic surfactants, polyoxyethylene alkyl ethers, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters. One or more of these water-soluble resins and surfactants may be selected and used in combination. When the amount is small, the dispersing effect to be added is weak, and when the amount is large, there is a concern that the dissolution balance of each composition in the ink may be disrupted and various problems may occur. 1-20% by weight is preferred.

Further, using an aqueous ink base in which a pigment is dispersed in an aqueous medium is advantageous in producing a pigment ink. Specifically, Fuji SP Black 8
031, 8119, 8167, 8276, 83
81, 8406, FujiSP RED 5096,
5111, 5193, 5220, 5543, 5544, Fuji SP Bordeaux 550
0, Fuji SPBlue 6062, 6133,
6134, 6401, Fuji SP Green
7051, Fuji SP Yellow 4060,
4178, Fuji SP Violet 901
1, Fuji SP Pink 9524, 952
7, Fuji SP Orange 534, Fuji
SPBrown 3074 (above, Fuji Dye Co., Ltd.)
Emacol Black CN, Emacol
Blue FBB, FB, KR, EmacolG
reen LXB, Emacol Violet B
L, Emacol Brown 3101, Emaco
l Carmmine FB, Emacol RED
BS, Emacol Orange R, Emacol
YellowFD, IRN, 3601, and FG
N, GN, GG, F5G, F7G, 10G
N, 10GN, Sandy Super Blac
KK, C, Sandy Super Gray
B, Sandye Super Brown SB, FRL, RR, Sandye Super Navy
Blue HRL, GLL, HB, FBL-
H, FBL-160, FBB, Sandy Su
per Violet BL H / C, same BL, same BL
N, Sandy Super Bordeaux F
R, Sandye Super Pink FBL, F5B, Sandye Super RubyF
R, Sandy Super Carmine F
B, Sandy Super Red FFG, R
R, same BS, Sandy Super Orange
FL, R, BO, Sandy Gold Ye
llow 5GR, same R, same 3R, Sandye Ye
llow GG, F3R, IRC, FGN, G
N, GRS, GSR-130, GSN-130,
GSN, 10GN (above, manufactured by Sanyo Dyeing Co., Ltd.), R
io Fast Black Fx 8012, 83
13, 8169, Rio Fast Red Fx
8209, 8172, Rio Fast Red S
Fx 8315, Fx 8316, Rio Fast B
lue Fx 8170, Rio Fast Blue
Fx 8170, Rio Fast Blue S
FX 8312, Rio Fast Green S
Fx 8314 (all manufactured by Toyo Ink Co., Ltd.), NKW
-2101, 2102, 2103, 2104, 2105, 2106, 2107, 2108, 2
117, 2127, 2137, 2167, 21
01P, 2102P, 2103P, 2104P,
2105P, 2106P, 2107P, 210
8P, 2117P, 2127P, 2137P, 2167P, NKW-3002, 3003, 300
4, 3005, 3007, 3077, 300
8, 3402, 3404, 3405, 340
7, 3408, 3377, 3602, 360
3, 3604, 3605, 3607, 367
7, 3608, 3702, 3703, 370
4, 3705, 3777, 3708, 601
3, 6038, 6559 (The above are Nippon Fluorescence Co., Ltd.)
Co., Ltd.), Cosmocolor S 1000F Series (manufactured by Toyo Soda Co., Ltd.), Victoria Yellow G-11, G-2
0, Victoria Orange G-16, G-21, Victoria Red G-19, G-22, Victoria Pink G-17, G-23, Victoria Green G-
18, G-24, Victoria Blue G-15, G
-25 (all made by Mikuni Shigyo Co., Ltd.), Pollux Blue PC5T-1020, Pollux Black PC8T
And Pollux series IT-1030 (all manufactured by Sumika Color Co., Ltd.). These can be used alone or in combination of two or more.

In addition to water, which is essential as a solvent or a dispersion medium, various water-soluble organic solvents can be used, and these have various qualities as aqueous inks, for example, prevention of ink drying at a pen tip, low temperature It is used for purposes such as prevention of ink freezing and a dispersion medium for pigments. Specifically, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, thiodiethylene glycol, hexylene glycol, tetralin, and glycerin; , Ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, ethylene glycol monobutyl ether, Propylene grease Over mono butyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether,
Triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate , Ethylene glycol monophenyl ether, ethers such as propylene glycol monophenyl ether, benzyl alcohol, alcohols such as methanol, ethanol, propanol, isopropanol, butanol, N-methyl-2-pyrrolidone, 2-pyrrolidone and the like can be used; These can be used alone or in combination of two or more. A. When the amount is small, insoluble or agglomerated substances are generated due to insufficient dissolution or dispersion of each composition in the ink, and when the amount is large, the concentration of each composition in the ink becomes small and the effect is small. Therefore, the content is preferably 5 to 40% by weight based on the total amount of the ink.

In addition to the cross-linked N-vinylcarboxylic acid amide, which is an essential component, a water-soluble polymer can be used in combination for adjusting the viscosity of the ink or stabilizing the dispersion of the coloring agent and the like. Specifically, polyvinyl alcohol, polyvinyl methyl ether, sodium polyacrylate, carboxyvinyl monomer, polyethylene oxide, copolymer of vinyl acetate and polyvinylpyrrolidone, alkali metal salt of acrylic resin, copolymer of acrylic acid and alkyl methacrylate , Natural gum arabic, tragacanth gum, xanthan gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, casein, dextran, semi-synthetic methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium starch glycolate, sodium alginate, alginic acid Propylene glycol esters, and derivatives thereof, and the like.

In order to suppress the inhibition of the outflow of ink in the ink passage due to the generation of mold, sodium dehydroacetate, 1,2-benzothiazalin-3-one, methyl-
An appropriate amount of a preservative and fungicide such as 2-benzimidazole carbamic acid ester and sodium benzoate can also be added.

Further, a corrosion inhibitor such as benzotriazole and ethylenediaminetetraacetic acid for preventing metal corrosion and a fatty acid such as oleic acid as a solubilizer can be added.

In producing the ink of the present invention, various conventionally known methods can be employed. For example, it can be easily obtained by mixing and dispersing with a disperser such as a stirrer such as a turbo mixer or a ball mill, a side grinder, a speed line mill, or a roll mill.

[0017]

The reason why the use of an ink using a cross-linked poly N-vinyl carboxylic acid amide and a sucrose fatty acid ester in combination is effective in suppressing the wear of the ball seat is presumed as follows. . The crosslinked poly N-vinylcarboxylic acid amide forms a microgel structure in an aqueous solution. This microgel is as large as 1 to 20 μm, and although it is rich in flexibility, it has little lubricity on the surface and easily breaks off. The sucrose ester has an extremely low concentration (0.03
% Or less), the surface becomes hydrophobic due to the formation of a micelle structure. However, if it is 0.1% or more, a double micelle structure is formed and the surface becomes smooth hydrophilic. As a result, the surface of the microgel having poor lubricity becomes smoother, and as a result, the friction between the ball and the ball seat is suppressed, so that the ball does not sink even during long-term use.

[0018]

The present invention will be described below in more detail with reference to examples.
In each of the examples, “parts” means “parts by weight”.

Example 1 Pollux Blue PC5T-1020 (blue aqueous pigment base, manufactured by Sumika Color Co., Ltd.) 20.00 parts GX-205 (cross-linked poly N-vinylacetamide, manufactured by Showa Denko KK) 40 parts Proxel GXL (preservative, manufactured by ICI Japan) 0.25 parts Ethylene glycol 32.00 parts Glycerin 15.00 parts Ryoto sugar ester S-770 (sucrose stearic acid ester, Mitsubishi Chemical Foods Corporation) 0.50 parts Ion-exchanged water 31.85 parts Among the above components, GX-205, ethylene glycol, glycerin, and water were mixed and stirred with a stirrer for 2 hours, and then left at 50 ° C. for 20 hours, and then GX -205, other than ethylene glycol, glycerin and water were added and mixed and stirred for 2 hours to obtain a blue aqueous pigment ink. .

Example 2 NKW-2107 (pink aqueous pigment base, manufactured by Nippon Fluorescent Chemical Co., Ltd.) 20.00 parts GX-205 1.20 parts Proxel GXL 0.25 parts Propylene glycol 26.00 parts glycerin 20. 00 parts Ryoto sugar ester P-1670 (sucrose palmitate ester, manufactured by Mitsubishi Chemical Foods Co., Ltd.) 0.20 parts Ion exchange water 32.35 parts GX-205, propylene glycol, glycerin, water Was mixed and stirred with a stirrer for 2 hours, and then allowed to stand at 50 ° C. for 20 hours. Then, except for GX-205, propylene glycol, glycerin and water were added and mixed and stirred for 2 hours to obtain a pink aqueous pigment ink. Was.

Example 3 FUJI SP RED 5544 (red aqueous pigment base, manufactured by Fuji Dye Co., Ltd.) 18.00 parts FUJI SP YELLOW 4178 (yellow aqueous pigment base, manufactured by Fuji Dye Co., Ltd.) 5.00 parts GX- 205 1.30 parts Benzotriazole 0.20 parts Ethylene glycol 20.00 parts Thiodiethylene glycol 18.00 parts Ryoto sugar ester OWA-1570 (sucrose oleate, manufactured by Mitsubishi Chemical Foods Corporation) 4.00 parts Ions 37.50 parts of exchanged water In the above components, GX-205, ethylene glycol, thiodiethylene glycol, and water were mixed and stirred with a stirrer for 2 hours, and then left at 50 ° C. for 20 hours, followed by GX-205.
205, ethylene glycol, thiodiethylene glycol and water were added and mixed and stirred for 2 hours to obtain a red aqueous pigment ink.

Example 4 FUJI SP MAGENTA 9316 (Magenta aqueous pigment base, manufactured by Fuji Color Co., Ltd.) 20.00 parts NA-010 1.45 parts Proxel GXL 0.25 parts Ethylene glycol 20.00 parts Glycerin 20 0.000 parts Ryoto sugar ester L-1695 (sucrose laurate ester, manufactured by Mitsubishi Chemical Foods Co., Ltd.) 1.50 parts Ion-exchanged water 36.80 parts Of the above components, GX-205, ethylene glycol, glycerin, water Was mixed and stirred with a stirrer for 2 hours, and then allowed to stand at 50 ° C. for 20 hours. Then, except for GX-205, ethylene glycol, glycerin and water were added and mixed and stirred for 2 hours to obtain a magenta aqueous pigment ink. Was.

Example 5 FUJI SP BLACK 8922 (black pigment base, manufactured by Fuji Dye Co., Ltd.) 18.00 parts GX-205 1.35 parts Proxel GXL 0.25 parts Ethylene glycol 16.00 parts Glycerin 15.00 parts Ryoto Sugar Ester S-1670 (sucrose stearic acid ester, manufactured by Mitsubishi Chemical Foods Co., Ltd.) 0.20 parts Ion-exchanged water 49.20 parts Among the above components, GX-205, ethylene glycol, glycerin, and water were agitated. After stirring for 2 hours at 50 ° C., the mixture was allowed to stand at 50 ° C. for 20 hours, and then the components other than GX-205, ethylene glycol, glycerin and water were added and mixed and stirred for 2 hours to obtain a black aqueous pigment ink.

Comparative Example 1 Ryoto sugar ester S-77 in Example 1.
A water-based blue pigment ink was obtained in the same manner as in Example 1 except that ion-exchanged water was added in the same amount except for 0.

Comparative Example 2 In Example 2, Ryoto Sugar Ester P-16
A yellow aqueous pigment ink was obtained in the same manner as in Example 2 except that ion-exchanged water was added in the same amount except for 70.

Comparative Example 3 Ryoto Sugar Ester OWA-
An aqueous red pigment ink was obtained in the same manner as in Example 3 except that ion-exchanged water was added in the same amount except for 1570.

The aqueous pigment inks obtained in the above Examples 1 to 5 and Comparative Examples 1 to 3 were made of polypropylene made by connecting a stainless ballpoint pen tip (ball material: cemented carbide) having a ball diameter of 0.4 mm to one end. 0.8 g was charged into a transparent ink container composed of a hollow shaft cylinder to prepare a test sample, and the writing distance and the ball sink amount were tested.

Writing distance: Using a rotating continuous spiral writing tester (writing tester MODEL TS-4C-20 manufactured by Seiki Kogyo Kenkyusho) at a writing speed of 7 cm / sec and a load of 100.
g, continuous writing was performed at a writing angle of 70 °, and the writing distance was measured until a continuous handwriting was not obtained (handwriting was blurred). (However, all of the filled inks were used in Examples 1 to 5. In Comparative Examples 1 to 3, about 10 to 20% of the filled ink remained, but the handwriting was markedly blurred. )

Ball sinking amount: In the above-described writing test, the difference between the ball protrusion length before writing and the ball protrusion length after 400 m continuous writing was defined as the ball sinking amount. The ball projection length was measured by placing the ballpoint pen sideways, pressing a stainless steel plate against the ball tip of the ballpoint pen tip with a 200 g load so that the ball was in contact with the ball receiving seat, and using a tool microscope (digital The length from the open end of the ballpoint pen tip to the tip of the ball was measured using a small-sized measuring microscope system (STM, MMDC201 manufactured by Olympus Optical Industry Co., Ltd.).

[0030]

[Table 1]

[0031]

As described above in detail, the water-based pigment ink according to the present invention has a sufficient initial object of reducing the wear and deformation of the ball seat due to the rotation of the ball and preventing the sinking of the ball as much as possible. Can be achieved. Accordingly, it is possible to realize that the handwriting is not blurred even when writing over a long distance.

Claims (1)

[Claims] 1. An aqueous pigment ink for ballpoint pens, comprising a sucrose fatty acid ester in an aqueous ink comprising at least water, a pigment and a cross-linked poly N-vinyl carboxylic acid amide.