JP2001064559A - Water-based ink for ballpoint pens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-base ink that can alleviate the wear and deformation of the ball socket due to ball rotation and give a nonskipping writing even after long-distance writing by mixing water with an acrylic acid/alkyl methacrylate copolymer, a coloring pigment, and carbon black in an amount smaller than a specified amount. SOLUTION: The amount of the carbon black used is below 0.1 wt.% based on the entire weight of the ink. The carbon black is exemplified by any one of carbon backs having a pH of 6 or below, a pH of 6-9, and a pH of 9 or above in view of surface activity and is exemplified by ant one furnace black, channel black thermal black, and lamp black in view of production process. The acrylic acid/alkyl methacrylate copolymer acts as a water-soluble thickener in the ink and is exemplified by PEMULEN TR-1 (trade mark, a product of Goodrich Co.). It is desirable that the copolymer is used in an amount of 0.10-0.50 wt.% based on the entire weight of the ink, and that the pigment is used in an amount of 0.1-40 wt.% based on the entire weight of the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called metal ball-point pen tip as a writing member, in which a ball made of a cemented carbide material is held and held in a ball holder made of an alloy such as stainless steel as a writing member. The present invention relates to a water-based ink used for a ball-point pen that discharges ink by using the ink.

[0002]

2. Description of the Related Art Conventionally, a ball-point pen has a relatively thin handwriting and is more likely to be worn or crushed even when used for a long period of time as compared with a writing instrument having a fiber nib or a resin nib. It is widely used because of little change in handwriting width. The water-based ink used for such a ballpoint pen is known to have a relatively low viscosity of 1 to several cp (25 ° C.) and a relatively high viscosity of 50 cp or more (25 ° C.). Those having 1 to several cp (25 ° C.) are mainly used for ballpoint pens having a structure using an ink occluding body such as a fiber bundle or a communicating porous body, and those having 50 cp or more (25 ° C.) are mainly used for an ink reservoir. Is used for a structure using a hollow cylindrical body.

In the above-described ball-point pen having a metal ball-point pen tip, the rotation of the ball causes the metal to come into contact between the ball and the ball receiving portion of the ball holder, and the hard metal in the ink such as pigment during that time. It is known that a component acts as a wear agent through the interposition of components. When such a thing is written over a long distance, the ball receiving seat is worn, and the minimum height of the ball with respect to the tip of the ball holder is reduced, so-called ball sinking. In the case of a ballpoint pen tip where the ball sinks, the tip of the ball holder may come into contact with the surface to be written, which may be caught and hinder a smooth writing feeling, or the ink formed on the ball receiving seat. Of the flow holes, the portion hidden by the ball was widened and the ink ejection was sometimes insufficient. In any case, a problem such as faint handwriting or heavy writing feeling occurs.
In order to solve this problem, for example, a resin that swells with a solvent such as water, such as an acrylic acid-alkyl methacrylate copolymer, is added to the ink to directly contact the metal between the ball and the ball seat. Attempts have been made to suppress the sinking of balls by minimizing the effect of hard solid components such as pigments acting as abrasives. This is because the resin that swells due to the solvent is in a coil shape when dried,
A solvent such as water is incorporated into the molecule to form a gel, and this gel acts as a cushion between the ball and the ball seat, thereby suppressing wear and deformation of the ball seat. It is expected.

[0004]

However, in a ballpoint pen, a strong force is always applied to the ball seat by the rotation of the ball during writing, so that an acrylic acid-alkyl methacrylate copolymer interposed between the ball and the ball seat is used. High shear force is applied to the gel, and the gel is broken.
As a result, if the gel breaks, the wear and deformation of the ball seat cannot be sufficiently suppressed. If the effect is improved by adding a large amount of the resin that forms the above-mentioned gel, the viscosity of the entire ink increases, which causes a problem that it is difficult to discharge the ink from the gap at the tip of the ballpoint pen tip. Of course, if the addition amount is small, the effect of preventing abrasion cannot be expected, and the dispersion of the ink itself will be deteriorated. As a result, in the above-described related art, wear and deformation of the ball receiving seat are not sufficiently suppressed, and writing is blurred when writing over a long distance.

An object of the present invention is to provide a ball by rotating a ball.
To provide a water-based ink for ball-point pens that ensures good ink dischargeability by minimizing wear and deformation of the cradle seat and prevents blurring of handwriting even when writing over long distances. It is in.

[0006]

That is, the present invention provides water,
The gist of the present invention is a water-based ink for a ballpoint pen, comprising at least an acrylic acid-alkyl methacrylate copolymer, a chromatic pigment, and carbon black in an amount of less than 0.1% by weight based on the total amount of the ink.

The acrylic acid-alkyl methacrylate copolymer mainly swells in the ink to form a gel structure and functions as a cushion material, to prevent sinking of the ballpoint pen tip ball and to obtain clear handwriting. It is intended to be used as a dispersion stabilizer for ink. Commercially available products include PEMULEN TR-1, PEM
ULEN TR-2, Carbopol ETD 20
20, Carbopol 1382 (above, Good-
rich (USA)). Since the acrylic acid-alkyl methacrylate copolymer also acts as a water-soluble thickener in the ink, it increases the viscosity of the entire ink, stabilizes the dispersion by retaining the colorant, or improves the fluidity of the ink. Various problems such as prevention of ink leakage due to the lowering can be suppressed.
The amount used cannot be determined unconditionally in consideration of the interaction with other inks.However, if the amount is too small, the ink viscosity is too low and the dispersion of the colorant becomes poor, or the ink is stored in a cylinder as an ink reservoir. Or if it is too large, the ink will be too thick and the ink will not be easily ejected due to the rotation of the ball.
0.50% by weight is preferred.

[0008] Carbon black is the above-mentioned acrylic acid-
It is used to suppress the wear and deformation of the ball seat by strengthening the gel structure of the alkyl methacrylate copolymer and making the gel hard to break during writing. Examples of the surface activity of carbon black include those having a pH of 6 or less (acidic), pH of 6 to 9 (neutral), and pH of 9 or more (alkaline). Furnace black,
Channel black, thermal black, and lamp black. Specific examples of carbon black include Special Black 6, S170, and S170.
610, 5, 5, 4A, 550, 35, 2
50, 100, Printex 150T, U, V, 140U, 140V, 95, 90, 8
5, same 80, same 75, same 55, same 45, same P, same XE
2, L6, L, 300, 30, 30, 35
25, 200, A, and G (all made by Degussa Japan Co., Ltd.), # 2400B, # 2350, # 230
0, # 2200B, # 1000, # 950, # 900,
# 850, # MCF88, MA600, MA100, M
A7, MA11, # 50, # 52, # 45, # 44, #
40, # 33, # 32, # 30, CF9, # 20B, #
4000B (Mitsubishi Chemical Industries, Ltd.), MONA
RCH 1300, 1100, 1000, 90
0, 880, 800, 700, MOGULL, R
EGAL 400R, 660R, 500R, 33
0R, 300R, 99R, ELFTEX 8, 1
2. BLACK PEARLS 2000 (above, manufactured by Cabot Co. LTD, USA), Raven700
0, 5750, 5250, 5000, 350
0, 2000, 1500, 1255, 125
0, 1200, 1170, 1060, 104
0, 1035, 1020, 1000, 890
H, 890, 850, 790, 780, 76
0, 500, 450, 430, 420, 41
0, 22, 22, 16, 825 Oil BEA
ds, H20, C, Conductex 97
5, 900, and SC (the above are manufactured by Colombian Carbon Japan Co., Ltd.). Specific examples of the aqueous ink base in which carbon black is dispersed in an aqueous medium include Fuji SP Black 8010, and the same. 8
031, 8119, 8167, 8230, 82
76, 8301, 8381, 8406, 855
6, 8568, 8682, 8796, 888
1, 8882, 8912, 8917, 8921,
8922, 8923 (all made by Fuji Dye Co., Ltd.),
Emacol Black CN, Sandy Su
per Black K, C (the above, manufactured by Sanyo Dyeing Co., Ltd.), Rio Fast Black Fx8
012, 8313, 8169, EMBlack K
-14, EM Black K-16, EM Black
kK-18, EM Black B-4 (all manufactured by Toyo Ink Co., Ltd.), Pollux Black PC8T135
Pollux series (above, manufactured by Sumika Color Co., Ltd.)
And the like. These may be used alone or in combination of two or more. However, when the total amount of carbon black is large, color separation of handwriting occurs, so that it is less than 0.1% by weight based on the total amount of ink.

As the chromatic color pigments, those conventionally used in water-based inks can be used without limitation. Specific examples thereof include BS-605 and BS-607 (all manufactured by Toyo Aluminum Co., Ltd.), Bronze powder P-555, P-7
77 (manufactured by Nakajima Metal Foil Industry Co., Ltd.), Bronze Powder 3L5, 3L7 (above, Fukuda Metal Foil Industry Co., Ltd.)
Metal powder pigments such as yellow iron oxide, red iron oxide, ultramarine, navy blue, cobalt blue, cerulean blue,
Inorganic pigments such as cobalt green, chrome green, and chromium oxide, Hansa A-10G, 5G, 3G, 4, GR, A, benzidine yellow, permanent yellow NCG, tartrazine lake, quinoline yellow, Sudane 1, Permanent Orange, Indus Ren Brilliant Orange GN, Permanent Brown FG, Para Brown, Permanent Red 4R, Fire Red, Brilliant Carmine BS, Pyrazolone Red, Lake Red C, Quinacridone Red, Brilliant Carmine 6B, Bordeaux 5B, Thioindigo Red And 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 silicate, zinc cadmium sulfate, calcium sulfide, strontium sulfide, and calcium tungstate may be used. The above-mentioned pigments can be used alone or in combination of two or more.The amount of use varies depending on the color tone and the like, but when the amount is small, the color development of the ink is poor, and when the amount is large, the dispersion is insufficient and various problems occur. 0.1 to 40% by weight based on the total amount is preferred.

[0010] Further, the use of an aqueous ink base in which a pigment is dispersed in an aqueous medium is advantageous in producing a pigment ink. Specifically, Fuji SP Red 509
6, 5111, 5193, 5220, 554
3, 5544, Fuji SP Bordeaux
5500, Fuji SP Blue 6062, 6
133, 6134, 6401, Fuji SP G
reen 7051, Fuji SP Yellow
4060, 4178, Fuji SP Violet
9011, 9585, 9586, Fuji SP
Pink 9524, Pink 9527, Fuji SP
Orange 534, FUji SPBrown 3
074, FUJI SP Magenta 9319
(The above are manufactured by Fuji Dye Co., Ltd.), Emacol Blue
FBB, FB, KR, Emacol Green
LXB, Emacol Violet BL, Ema
col Brown 3101, Emacol Car
mmine FB, Emacol Red BS, Em
acol Orange R, Emacol Yellow
ow FD, same IRN, same 3601, same FGN, same G
N, GG, F5G, F7G, 10GN, 10
G, Sandy Super Gray B, San
Dye Super Brown SB, same FRL, same RR, Sandye Super Green L5
G, GXB, Sandy SuperNavy B
lue HRL, GLL, HB, FBL-H, FBL-160, FBB, Sandy Super
Violet BL H / C, BL, Sandye
Super Bordeaux FR, Sandye
Super Pink FBL, F5B, Sand
ye Super Rubine FR, Sandye
super Carmmine FB, Sandye
Super Red FFG, RR, BS, Sa
ndye SuperOrange FL, R, B
O, Sandye Gold Yellow 5GR, R, 3R, Sandye Yellow GG, F
3R, IRC, FGN, GN, GRS, GS
R-130, GSN-130, GSN, 10GN
(The above are manufactured by Sanyo Dyeing Co., Ltd.), Rio Fast Re
dFx 8209, 8172, Rio Fast R
ed S Fx 8315, 8316, Rio Fa
st Blue Fx 8170, Rio Fast
Blue FX 8170, Rio Fast Blue
e S Fx 8312, Rio Fast Green
n S Fx 8314, EM Yellow FG,
EM Yellow 3G, EM Yellow G,
EM Yellow GR, EM Yellow 2
R, EM Yellow 2RN, EM Yellow
3R, EM Yellow YSR-5, EM Yellow
lowRD-5, EM Orange O, EM Or
angel OL, EM Scarlet 2Y, EM
Scarlet 2YD, EM RED R, EMRE
DBH, EM RED Y-3, EM Fuchsi
n, EM Pink2B, EM Violet F4
B, EM Green G, EM Green B, E
M Cobalt Blue, EM Blue NC
B, EM Blue 2G, EM Blue 2G-1
0, EM Royal Blue RA, EM Bro
wn R (all manufactured by Toyo Ink Co., Ltd.), NKW-21
01, 2102, 2103, 2104, 210
5, 2106, 2107, 2108, 211
7, 2127, 2137, 2167, 2101
P, 2102P, 2103P, 2104P, 2
105P, 2106P, 2107P, 2108
P, 2117P, 2127P, 2137P, 2
167P, 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 manufactured by Mikuni Shigyo Co., Ltd.), Pollux PC5
Pollux series such as T1020 and Poluc Red IT1030 (all manufactured by Sumika Color Co., Ltd.), etc., and these can be used alone or in combination of two or more.

Here, it is preferable to use a dispersant in combination with the pigment. However, conventionally used anionic or nonionic surfactants which are used as a pigment dispersant can be used. As an example, alkyl sulfate, polyoxyethylene alkyl ether sulfate,
N-acyl amino acids and salts thereof, N-acylmethyl taurine salts, polyoxyethylene alkyl ether acetates,
Anionic surfactants such as alkyl sulfocarboxylates, α-olefin sulfonates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl ethers, sorbitan alkyl esters, polyoxyethylene sorbitan Nonionic surfactants such as alkyl esters are included. One or more of these surfactants may be selected and used in combination. When the amount is small, the dispersion stabilizing 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. On the other hand, 0.1 to 20% by weight is preferable.

In addition to water, which is essential as a solvent or a dispersion medium, various water-soluble organic solvents can be used. These have various qualities as aqueous inks, for example, prevention of ink drying at a pen tip, 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 And 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 mono Butyl ether, propylene glycol 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, dipropylene glycol monomethyl ether acetate, ethylene glycol monophenyl ether ,
Ethers such as propylene glycol monophenyl ether, benzyl alcohol, methanol, ethanol,
Alcohols such as propanol, isopropyl alcohol and butanol, N-methyl-2-pyrrolidone, 2-pyrrolidone and the like can be used, and these can be used alone or in combination of two or more. 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. And various problems occur.
~ 40% by weight is preferred.

In addition to the acrylic acid-alkyl methacrylate copolymer, various polymers can be used for adjusting the viscosity of the ink or as a dispersant for the above-mentioned pigment. As an example, natural gum arabic, tragacanth gum, xanthan gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, casein, dextran, shellac, etc., glucosides such as saponin, semi-synthetic methylcellulose, carboxycellulose, hydroxymethylcellulose, etc. Cellulose derivatives, sodium starch glycolate, sodium alginate, propylene glycol alginate and derivatives thereof, synthetic lignin sulfonates, polyacrylates, salts of styrene-acrylic acid copolymers, vinyl naphthalene-maleic Acid copolymer salt, sodium salt of β-naphthalenesulfonic acid formalin condensate, anionic polymers such as phosphate, polyvinyl alcohol,
Polyvinyl methyl ether, polyethylene glycol,
Examples include nonionic polymers such as polyethylene oxide, carboxyvinyl polymers, copolymers of vinyl acetate and polyvinylpyrrolidone, and poly N-vinylacetamide. One or more of these may be selected and used in combination. If the amount used is small, the dispersion of the ink itself will be poor, and if it is large, the viscosity of the ink will increase and the ink ejection will deteriorate, or the dissolution balance of each composition in the ink will be disrupted and various problems will occur. Since there is a fear of occurrence, the content is preferably 0.1 to 20% by weight based on the total amount of the aqueous ink.

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

Further, in the case of a writing instrument using a metal in a portion which comes into contact with the ink, a rust inhibitor such as an N-acylamino acid and / or a salt thereof, benzotriazole, ethylenediaminetetraacetic acid or the like for preventing corrosion of the metal. In addition, a fatty acid such as oleic acid can be added as a solubilizing agent.

In addition to the above, dyes which can be generally used in aqueous inks such as acid dyes, basic dyes, direct dyes, food dyes, reactive dyes, disperse dyes, vat dyes, etc .;
Potassium hydroxide, triethanolamine, 2-amino-
PH of 2-methyl-propanediol, lithium acetate, etc.
Conditioning agents, sugar alcohol, urea, etc.
Various agents such as a handprint bleeding preventive for various polymer fine particles can also be appropriately 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 grinding with a disperser such as a ball mill, a sand grinder, a speed line mill, and a roll mill.

[0018]

The reason why the addition of carbon black to the ink is effective in suppressing the wear of the ball seat is presumed as follows. The acrylic acid-alkyl methacrylate copolymer is bundled into a coil when dried, but carbon black added ink incorporates carbon black into the copolymer molecules along with solvents such as water and water-soluble organic solvents. It is. At this time, since the surface of the carbon black is covered with carboxyl groups, hydroxyl groups, carbonyl groups, etc., the hydrogen bond with the carboxyl groups in the copolymer molecule improves the gel structure strength compared to the solvent alone. Will do. As a result, the gel is less likely to be broken, and acts sufficiently as a cushion between the ball seat and the ball, so that wear and deformation of the ball seat can be easily suppressed. Also, in the structure of carbon black, the net plane of crystallites is oriented parallel to the particle surface, so when a force is applied to the carbon black by the rotation of the ball, the net plane slides easily. Also has the function of suppressing wear and deformation of the ball seat. As a result, sinking of the ball is prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. The viscosities of the respective inks in the examples and comparative examples were measured with an ELD viscometer ST rotor 10 rpm manufactured by Tokimec Co., Ltd. The temperature at the time of the measurement was 25 ° C. In each of the examples, “parts” means “parts by weight”.

Example 1 MICROJET BLACK M-800 (black aqueous pigment base, manufactured by Orient Chemical Industry Co., Ltd.) 0.08 parts FUJI SP RED 5544 (red aqueous pigment base, manufactured by Fuji Dye Co., Ltd.) 19.92 parts 2% aqueous solution of PEMULEN TR-1 (acrylic acid-acryl methacrylate copolymer, manufactured by Good-rich (USA)) 18.00 parts Proxel GXL (preservative, manufactured by ICI Japan) 0.25 parts ethylene Glycol 3.60 parts Glycerin 15.00 parts SX8742 (A) -05 (aqueous dispersion of polymer fine particles, manufactured by JSR Corporation) 20.00 parts PO-20 (monosaccharide alcohol / polysaccharide alcohol mixture, Towa Chemical Industry) 4.00 parts Sarcosinate OH (oleoyl sarcosine, Nikko Chemicals Co., Ltd.) 1.00 part Benzotriazole 0.40 part 2-Methyl-2amino-1,3-propanediol 0.50 part Water 17.25 parts The above components were mixed and stirred for 2 hours, and a red aqueous ink having a viscosity of 1620 cp was obtained. I got

Example 2 MA100 (carbon black, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) 0.08 parts Sandy Super Violet BL 15.50 parts 2% aqueous solution of PEMULEN TR-2 17.00 parts Proxel GXL 0.25 parts propylene Glycol 2.60 parts glycerin 13.50 parts NKW-75 (aqueous dispersion of polymer fine particles, manufactured by Nippon Fluorescent Chemical Co., Ltd.) 25.00 parts PO-500 (monosaccharide alcohol / polysaccharide alcohol mixture, Towa Kasei Kogyo Co., Ltd.) 3.00 parts Sarcosinate OH 0.80 parts Benzotriazole 0.20 parts 2-amino-2-methyl-1,3-propanediol 0.40 parts Water 21.67 parts The above components are mixed for 2 hours. After stirring, a purple aqueous ink having a viscosity of 1380 cp was obtained.

Example 3 PRINTEX 25 (carbon black, manufactured by Degussa Japan KK) 0.05 parts FUJI SP BLUE 6401 15.95 parts FUJI SP YELLOW 4178 (yellow aqueous pigment base, manufactured by Fuji Dye Co., Ltd.) 00 parts 2% aqueous solution of PEMULEN TR-2 19.00 parts Proxel GXL 0.25 parts Ethylene glycol 3.70 parts Glycerin 17.00 parts Lowpaque OP-62 (water dispersion of polymer fine particles, ROHM AND HAAS ( U.S.A.) 10.00 parts Sarcosinate LH (lauroyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.) 1.20 parts Benzotriazole 0.30 parts 2-amino-2-methyl-1,3-propanediol 0.60 parts Water 23.95 parts The above components were mixed and stirred for 2 hours, To give a green water-based ink of 530cp.

Example 4 MICROJET BLACK M-800 0.20 parts FUJI SP BLUE 6401 (blue aqueous pigment base, manufactured by Fuji Dye Co., Ltd.) 16.70 parts FUJI SP VIOLET 9586 (purple aqueous pigment base, Fuji Dye 3.30 parts 2% aqueous solution of PEMULEN TR-1 18.00 parts Proxel GXL 0.25 parts Ethylene glycol 3.60 parts Glycerin 15.00 parts SX8742 (A) -05 20.00 parts PO-205 0.000 parts Sarcosinate OH 1.00 parts Benzotriazole 0.40 parts 2-Amino-2-methyl-1,3-propanediol 0.60 parts Water 15.95 parts The above components are mixed and stirred for 2 hours, and the viscosity is 1740 cp. Was obtained.

Example 5 EM Black K-16 (black aqueous pigment base, manufactured by Toyo Ink Co., Ltd.) 0.20 parts EM Orange OL (orange aqueous pigment base, manufactured by Toyo Ink Co., Ltd.) 25.00 parts PEMULEN TR -1 2% aqueous solution 19.00 parts Proxel GXL 0.25 parts Ethylene glycol 4.20 parts Glycerin 16.50 parts NKW-75 20.00 parts Sarcosinate LH 0.90 parts Benzotriazole 0.40 parts 2-amino- 0.70 parts of 2-methyl-1,3-propanediol 12.85 parts of water The above components were mixed and stirred for 2 hours to obtain an orange aqueous ink having a viscosity of 1910 cp.

Comparative Example 1 MICROJET BLACK M-800 of Example 1
And a water-based red ink having a viscosity of 1610 cp was obtained in the same manner as in Example 1 except that water was added in an amount corresponding to 0.08 parts.

Comparative Example 2 The amount of MA100 in Example 2 was changed to 0.20 part, and water was adjusted to 21.5 parts.
The same procedure as in Example 2 was carried out except that the amount was 5 parts, and the viscosity was 139.
A 0 cp purple aqueous ink was obtained.

Comparative Example 3 A yellow aqueous ink having a viscosity of 1500 cp was obtained in the same manner as in Example 3 except that 0.05 parts of PRINTEX 25 of Example 3 was removed and water was added in that amount.

Comparative Example 4 MICROJET BLACK M-800 of Example 4
Was set to 0.50 parts and water was set to 15.65 parts, to obtain a blue aqueous ink having a viscosity of 1780 cp.

The aqueous inks obtained in Examples 1 to 5 and Comparative Examples 1 to 4 are each made of a polypropylene hollow shaft cylinder having one end connected to a stainless ballpoint pen tip (ball material: cemented carbide). A transparent ink container was filled with 0.8 g to prepare a test sample, and the ball sinking amount and the state of handwriting were tested.

Ball sinking amount: Using a rotation type continuous spiral writing tester (writing tester MODEL TS-4C-20 manufactured by Seiki Industry Laboratory), writing speed 7 cm / sec, load 1
00g and continuous writing at a writing angle of 70 °. At this time, 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 load of 200 g so that the ball was in contact with the ball receiving seat, and using a tool microscope ( Digital compact measuring microscope
Model STM-DH Olympus Optical Co., Ltd.
) Was used to measure the length from the open end of the ball pen tip to the tip of the ball.

[0031]

[Table 1]

[0032]

As described above in detail, the water-based ink according to the present invention can be used for long-distance writing by minimizing abrasion and deformation of the ball seat due to ball rotation and preventing ball sinking as much as possible. However, the initial purpose of keeping the handwriting intact can be sufficiently achieved.

Claims (1)

[Claims] An aqueous ink for a ballpoint pen comprising at least water, an acrylic acid-alkyl methacrylate copolymer, a chromatic pigment, and less than 0.1% by weight of carbon black based on the total amount of the ink.