JP2002294132A - Aqueous ink for writing implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous ink for writing implements which is reduced in the generation of blur during writing because of no agglomeration and sedimentation of a pigment even after a long time. SOLUTION: This aqueous ink comprises, at least, a coloring agent, water, and an acrylic acid/alkyl methacrylate copolymer crosslinked with allyl pentaerythritol and/or its salt, and the pH of this aqueous ink for the writing implements is not lower than 5 (25 deg.C).

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 for writing implements, in which generation of blurring during writing is suppressed as much as possible even after long-term aging because of the absence of aggregation and sedimentation of pigments even after long-term aging.

[0002]

2. Description of the Related Art The viscosity of an ink is closely related to the form of a writing instrument. For example, when filling a hollow pipe directly with ink, the ink is thickened so that the ink does not leak from the pen tip. Conventionally, the viscosity of a writing implement ink has been generally adjusted by adding a high molecular compound. In the case of an aqueous ink containing water as a solvent for the ink, for example, natural gum arabic, tragacanth gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, casein, xanthan gum, dextran, semi-synthetic methyl cellulose, ethyl cellulose, hydroxy Ethyl cellulose, carboxymethyl cellulose, starch glycolic acid, alginic acid, propylene glycol alginate, synthetic polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylic acid, carboxyvinyl polymer, polyethylene oxide, copolymer of vinyl acetate and polyvinyl pyrrolidone,
One or more water-soluble polymer compounds such as polyacrylic acid have been used.

[0003]

When the above-mentioned water-soluble polymer compound is used as an ink viscosity modifier, the dye is insolubilized depending on the kind of the dye, and the pigment aggregates depending on the kind of the pigment. There was a problem that would occur.

When the above-mentioned water-soluble polymer compound is used as a viscosity modifier for an aqueous ballpoint pen ink, the dye is insolubilized depending on the type of the colorant dye, and the pigment aggregates depending on the type of the colorant pigment. There is a problem that sedimentation occurs and the ink flow path is blocked, so that the ink ejection amount is remarkably reduced at the time of writing, or that the ink is not completely discharged at all.

An object of the present invention is to provide a water-based ink for a writing implement which suppresses the occurrence of blurring during writing even after a long period of time by suppressing the insolubilization of the dye and the coagulation and sedimentation of the pigment even after a long period of time. It is in.

[0006]

Means for Solving the Problems The present invention provides at least:
The gist of the present invention is a water-based ink for a writing implement, which comprises an acrylic acid-alkyl methacrylate copolymer crosslinked with a colorant, water and allylpentaerythritol and / or a salt thereof.

Conventionally known pigments can be used as colorants,
As specific examples, SpecialBlack 6 and S
170, S610, 5, 5, 4, 4A, 550,
35, 250, 100, Printex 150
T, U, V, 140U, 140V, 95, 90, 85, 80, 75, 55, 45, 45, P, XE2, L6, L, 300 30, 30, 35, 25, 200, A, G (all manufactured by Degussa Japan KK), # 2400B, # 235
0, # 2300, # 2200B, # 1000, # 95
0, # 900, # 850, # MCF88, MA600,
MA100, MA7, MA11, # 50, # 52, # 4
5, # 44, # 40, # 33, # 32, # 30, CF
9, # 20B, # 4000B (Mitsubishi Chemical Industries, Ltd.), MONARCH 1300, 1100,
1000, 900, 880, 800, 70
0, MOGULL, REGAL 400R, 660
R, 500R, 330R, 300R, 99R,
ELFTEX 8, 12 and BLACK PEARLS
2000 (above, USA, Cabot Co. Ltd.
Manufactured), Raven7000, 5750, 5250,
5000, 3500, 2000, 1500, 1255, 1250, 1200, 1170, 1
060, 1040, 1035, 1020, 10
00, 890H, 890, 850, 790, 780, 760, 500, 450, 430, 420, 410, 22, 16, 16, and 825
Oil Beads, H20, C, Conduc
carbon black such as tex 975, 900, and SC (all manufactured by Colombia Carbon Japan Co., Ltd.);
A-10, same 10P, same 15, same 20, same 30, same 3
5, 60, 80, 90, KR-310, 38
0, 460, 480 (Titanium Industry Co., Ltd.
Titanium oxide such as P25 (manufactured by Nippon Aerosil Co., Ltd.), BS-605, and 607 (all manufactured by Toyo Aluminum Co., Ltd.), and bronze powders P-555 and P-77.
7 (manufactured by Nakajima Metal Foil Industry Co., Ltd.), Bronze Powder 3L5, 3L7 (above manufactured by Fukuda Metal Foil Industry Co., Ltd.)
Metal powder pigments, such as black iron oxide, yellow iron oxide, red iron oxide, ultramarine, navy blue, cobalt blue, chrome green, chromium oxide and other inorganic pigments, Hansa Yellow 10G,
5G, 3G, 4, GR, A, Benzidine Yellow, Permanent Yellow NCG, Tartrazine Lake,
Quinoline yellow, Sudanese 1, permanent orange,
Indus Ren Brilliant Orange GN, Permanent Brown FG, Para Brown, Permanent Red 4
R, Fire Red, Brilliant Carmine BS, Pyrazolone Red, Lake Red C, Quinacridone Red, Brilliant Carmine 6B, Bordeaux 5B, Thioindigo Red, Fast Violet B, Dioxane Violet, Alkaline Blue Lake, Phthalocyanine Blue, Indigo, Acid Green Lake, Organic pigments such as phthalocyanine green are exemplified. Also,
In addition, inorganic fluorescent pigments such as zinc sulfide, zinc silicate, zinc cadmium sulfate, calcium sulfide, strontium sulfide, and calcium tungstate can be used. The colorants described above can be used alone or in combination of two or more, and the amount used varies depending on the color tone and the like. However, when the amount is small, the color development of the ink is deteriorated, and when the amount is large, the colorant is insolubilized and precipitated. The amount is preferably 1 to 20% by weight based on the total amount of the aqueous ink, since the ink flow path is clogged due to the dispersibility or agglomeration due to reduced dispersibility.

Here, when a pigment is used as a colorant,
It is preferable to use a dispersing agent in combination, but as the dispersing agent, a water-soluble resin generally used conventionally, an anionic or nonionic surfactant, or the like can be used. As an example,
Natural gums such as gum arabic and gum tragacanth, glucosides such as saponin, cellulose derivatives such as methylcellulose, carboxycellulose and hydroxymethylcellulose, natural polymer compounds such as ligninsulfonate and shellac, polyacrylic acid, styrene-acrylic acid Examples include anionic polymer compounds such as polymers, vinyl naphthalene-maleic acid copolymers, and β-naphthalene sulfonic acid formalin condensates and salts thereof, and nonionic polymer compounds such as polyvinyl alcohol and polyethylene glycol. . Further, as a surfactant, alkyl sulfate, polyoxyethylene alkyl ether sulfate, N-acyl amino acid, N-acylmethyl taurine, polyoxyethylene alkyl ether acetic acid, alkyl sulfocarboxylic acid, α-olefin sulfonic acid, alkyl phosphoric acid And anionic surfactants such as polyoxyethylene alkyl ether phosphoric acid and salts thereof, and nonionic surfactants such as polyoxyethylene alkyl ethers, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters. One or more of these water-soluble resins and surfactants can be selected and used. When the amount is small, the dispersing effect to be added is weak, and when the amount is large, problems such as blurring of the writing line occur. Therefore, the amount is preferably 0.5 to 10% by weight based on the total amount of the aqueous ink. .

Further, in the case of pigment inks, it is advantageous in the production of pigment inks to use an aqueous ink base in which a pigment is dispersed in an aqueous medium. Specifically, Fuji S
PBlack 8031, 8119, 8167, 8276, 8381, 8406, Fuji SP
Red 5096, 5111, 5193, 522
0, Fuji SP Bordeaux 5500, F
uji SP Blue 6062, 6133, 6
134, 6401, Fuji SP Green 7
051, Fuji SP Yellow 4060, 4178, Fuji SP Violet 9011,
Fuji SP Pink 9524, 9527, F
uji SP Orange 534, FUji SP
Brown 3074, FUJI SP RED 5
543, 5544 (all manufactured by Fuji Dye Co., Ltd.), Em
acol Black CN, Emacol Blue
FBB, FB, KR, Emacol Green
LXB, EmacolViolet BL, Emaco
l Brown 3101, EmacolCarmmi
ne FB, Emacol Red BS, Emaco
l Orange R, Emacol Yellow
FD, IRN, 3601, FGN, GN, G
G, F5G, F7G, 10GN, 10G, Sa
ndye Super Black K, C, San
Dye Super Gray B, Sandy S
upper Brown SB, FRL, RR, Sa
ndye Super Green L5G, GX
B, Sandy Super Navy Blue
HRL, GLL, HB, FBL-H, FBL-
160, same FBB, Sandy Super Vio
let BL H / C, same BL, Sandy Sup
er Bordeaux FR, Sandy Sup
er Pink FBL, F5B, Sandy S
upperRubine FR, Sandy suppe
r Carmmine FB, Sandy Suppe
r Red FFG, RR, BS, Sandye
Super Orange FL, R, BO, Sa
ndye Gold Yellow 5GR, R, 3R, Sandy Ywllow GG, F3R,
Same IRC, Same FGN, Same GN, Same GRS, Same GSR-1
30, the same GSN-130, the same GSN, the same 10GN (all manufactured by Sanyo Dyeing Co., Ltd.), Rio FastBlack
Fx 8012, 8313, 8169, Rio
Fast Red Fx 8209, 8172, Ri
o Fast Red S Fx 8315, 831
6, Rio Fast Blue Fx 8170, R
ioFast Blue FX 8170, Rio F
ast Blue S Fx8312, Rio Fas
t Green S Fx 8314 (all manufactured by Toyo Ink Co., Ltd.), NKW-2101, 2102, 21
03, 2104, 2105, 2106, 210
7, 2108, 2117, 2127, 213
7, 2167, 2101P, 2102P, 21
03P, 2104P, 2105P, 2106P,
2107P, 2108P, 2117P, 212
7P, 2137P, 2167P, NKW-300
2, 3003, 3004, 3005, 300
7, 3077, 3008, 3402, 340
4, 3405, 3407, 3408, 347
7, 3602, 3603, 3604, 360
5, 3607, 3677, 3608, 370
2, 3703, 3704, 3705, 377
7, 3708, 6013, 6038, 6559
(The above are manufactured by Nippon Fluorescence Co., Ltd.), Cosmo Color S 100
0F series (manufactured by Toyo Soda Co., Ltd.), Victoria Yellow G-11, G-20, Victoria Orange G-1
6, G-21, Victoria Red G-19, G-
22, Victoria Pink G-17, Victoria G-23, Victoria Green G-18, Victoria G-24, Victoria Blue G-15, Victoria G-25
Pollux series such as Pollux PC5T1020, Pollux Black PC8T135, and Polluc Red IT1030 (all manufactured by Sumika Color Co., Ltd.). These can be used alone or in combination of two or more.

A dye may be used in combination for adjusting the color tone of the ink. Specific examples thereof include Japananol Fast Black D Conc (CI Direct Black 17), Water Black 100L (19), Water Black L-200 (19), and Water Black # 7.
(19), Kayaset Black W9 (19), Direct Fast Black B (22), Direct Fast Black AB (32), Direct Deep Black EX (38), Direct Deep Black (38 similar products) , Direct Fast Black Conch (Id. 51), Kayara Splague VGN (Id. 71), Kayak Direct Brilliant Yellow G (C.I.Direct Yellow 4), Direct Fast Yellow 5GL (Id. 2)
6), Aizen Brimura Yellow GCLH (44), Direct Fast Yellow R (50), Aizen Direct Fast Red FH (CI Direct Red 1), Nippon Fast Scarlet GSX (4),
Direct Fast Scarlet 4BS (23), Eisen Direct Durin BH (31), Direct Scarlet B (37), Kayak Direct Scarlet 3B (39), Eisen Buri Malabin Conch 2B
LH (75), Sumilight Red F3B (80),
Aizen Burimura Red 4BH (81) Kayasupurarubin BL (83), Kayasu Light Red F5G
(225), Kayasu Light Red F5B (22)
6), Kayalas Light Rose FR (227) Direct Sky Blue 6B (CI Direct Blue 1),
Direct Sky Blue 5B (15), Benzo Brilliant Sky Blue 8GS (41), Sumilite Supra Blue BRR Conc (71), Diebogen Turquoise Blue S (86), Water Blue # 3 (8)
6), Kayara Star Koizu Blue GL (86), Daiwa Blue 215H (87), Kayara Supra Blue F
F2GL (106), Kayaras Supra Blue FFRL
(Id. 108) Kayasu Splatter Turquoise Blue FBL
(199), Acid Blue Black 10B (CI Acid Black 1), Nigrosine (2), Water Black R455 (2), Water Black R510 (2), Suminol Milling Black 8BX (24), Kayanol milling black VLG (26), Kayano milling black BR
Conch (31), Mitsui Nylon Black GL (5)
2), Aizen Opal Black WH Extra Conc (52), Sumilan Black WA (52), Ranyl Black BG Extra Conc (107), Kayanol Milling Black TLB (109), Suminol Milling Black B (52) 109), Kayanol Milling Black TLR (110), Eisen Opal Black New Conc (119), Water Black 187
-L (154) Acid Yellow # 10 (CI Acid Yellow 1), Kayak Acid Brilliant Flavin FF (7: 1), Kayasil Yellow GG (17),
Xylene Light Yellow 2G 140% (17), Suminol Leveling Yellow NR (19), Water Yellow # 1 (23), Daiwatrazine (25),
Kayaktor Trazine (23), Suminol Fast Yellow R (25), Diacid Light Yellow 2GP (29), Suminol Milling Yellow O (38), Suminol Milling Yellow MR (42), Tar Yellow # 6 (42), Kayanol Yellow NFG (4)
9), Suminol Milling Yellow 3G (72), Suminol Fast Yellow G (61), Suminol Milling Yellow G (78), Kayanol Yellow N5G (1)
10), Sumino Milling Yellow 4G 200% (1
41), Kayanol Yellow NG (135), Kayanol Milling Yellow 5GW (127), Kayanol Milling Yellow 6GW (142), Sumitomo Fast Scarlet A (CI Acid Red 8), Kayak Silk Scarlet ( 9), Solar Rubin Extra (14), Daiwa New Koksin (18), Water Scarlet (18), Daiwa Red 102 (18), Eisenbon Saw RH (26), Daiwa Red 2 (No. 27), Suminol Leveling Brilliant Red S3B (No. 35), Kayasil Rubinol 3GS (No. 37), Eisenerythrosine (No. 51), Kayak Acid Rhodamine FB (No. 52), Daiwa Red No. 106 (No. 52) , Suminol Leveling Rubinol 3GP
(57), Diacid Alizarin Rubinol F3G
200% (82), alizarin rubinol 5G (8)
3), Aizen Eosin GH (87), Water Red # 2 (87), Daiwa Red 103WB (8)
7), Water Pink # 2 (92), Eisen Acid Phloxine PB (92), Daiwa Red No. 104 (92), Rose Bengal (94), Kayanol Milling Scarlet FGW (111), Kayanol Milling Rubin 3BW (129), Suminol Milling Brilliant Red 3BN Conc (131), Suminol Milling Brilliant Red BS (138), Eisen Opal Pink BH (186), Suminol Brilliant Red B Conch (249), Kayak Acid Brilliant Red 3BL (254), Kayak Acid Brilliant Red BL (265), Kayanol Milling Red GW (276), Mitsui Acid Violet 6BN (CI Acid Violet 1)
5), Mitsui Acid Violet BN (17), Water Violet # 1 (49), Water Violet # 5 (49), Daiwa Purple No. 1 (49), Ink Violet L10 (49), Sumitomo Patent Pure Blue Blue VX (CI Acid Blue 1), Water Blue # 106 (Same 1), Patent Blue AF
(No. 7), Water Blue # 9 (No. 9), Daiwa Blue No. 1 (No. 9), Ink Blue L20 (No. 9), Spranol Blue B (No. 15), Water Blue # 116
(15), Orient Soluble Blue OBC (2)
2), Orient Solble Blue OBX (22), Suminol Leveling Blue 4GL (23), Mitsui Nylon Fast Blue G (25), Kayasil Blue A
GG (40), Kayasil Blue BR (41), Mitsui Alizarin Safirol SE (43), Suminol Leveling Sky Blue R Extra Conc (6)
2), Mitsui Nylon Fast Sky Blue R (7)
8), Sumitomobrilliant indocyanine 6Bh / e
(83), Sandran cyanine N-6B 350% (90), Water Blue # 115 (90), Water Blue # 105 (90), Orient Soluble OBB (93), Spranol Cyanine 7BF
(100), Sumitomo Brilliant Blue 5G (1)
03), Acid Blue (103), Asilane Brilliant Blue FFR (104), Kayanol Milling Ultrasky SE (112), Kayanol Milling Cyanine 5R (113), Aizen Opal Cyanine 2GLH (158), Daiwa Guinea Green B (C.I.
I. Acid Green 3) Acid Brilliant Milling Green (9), Daiwa Green # 70 (1)
6), Kayanol Cyanine Green G (25), Suminol Milling Green G (27), acid dyes such as Water Orange # 17 (CI Acid Orange 56), and Water Yellow # 2 (CI. Food Yellow 3), Food Yellow No. 5 (CI Food Yellow 3) Food Red 3 (CI Food Red 14), Food Blue 2 (CI Acid Blue 74), Food For green 2
No. (CI Acid Green 5), food dyes such as Malachite Green (CI.42000), Victoria Blue FB (CI.44045), Methyl Violet FN (CI.42535), Rhodamine F4G
(CI. 45160), rhodamine 6GCP (C.I.
I. 45160).

As a solvent or a dispersion medium, various water-soluble organic solvents can be used in addition to essential water, and these have various qualities as an aqueous ink, for example, prevention of ink drying at a pen tip, It is used for the purpose of preventing ink freezing. 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 Monobutyl 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 mono Butyl ether, dipropylene glycol monomethyl ether acetate,
Ethylene glycol monophenyl ether, ethers such as propylene glycol monophenyl ether, benzyl alcohol, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, 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. The amount of the ink used is preferably 5 to 40% by weight based on the total amount of the ink, because when the amount is small, the effect of preventing the tip from drying and freezing is small, and when the amount is large, the handwriting tends to spread.

The acrylic acid-alkyl methacrylate copolymer crosslinked with allylpentaerythritol and / or its salt can be used to prevent the insolubilization of the dye or the coagulation and sedimentation of the pigment, or to fill the hollow pipe directly with the ink. Also used to thicken the ink so that the ink does not leak from the pen tip. Specifically, Pemulen TR-1, Pemulen T
R-2, Carbopol 1382, Carbopol ETD
2020 (all manufactured by Nikko Chemicals Co., Ltd.) and the like. The amount of the acrylic acid-alkyl methacrylate copolymer cross-linked with allyl pentaerythritol and / or the salt thereof is not specified unconditionally in consideration of the interaction with other ink composition components. The effect of preventing insolubilization of dyes and coagulation and sedimentation of pigments and the ability to prevent ink leakage are not sufficiently exhibited.If there is too much, the ink becomes too thick and the ink is difficult to discharge, resulting in marked blurring of handwriting. Therefore, the content is preferably 0.1 to 5.0% by weight based on the total amount of the ink. still,
The crosslinked structure of the acrylic acid-alkyl methacrylate copolymer crosslinked with allylpentaerythritol and / or its salt used in the present invention and the analysis of the crosslinker are analyzed by pyrolysis gas chromatography, NMR spectroscopy, and infrared absorption spectroscopy. , Mass spectrometry and the like.

The acrylic acid-alkyl methacrylate copolymer crosslinked with allylpentaerythritol and / or a salt thereof is sufficiently swollen when the pH of the solution is 5 or more, and the viscosity of the ink is stabilized. 5 or more is desirable. Incidentally, the pH of the ink may be adjusted by adding various known acidic substances or basic substances. Specifically, it is adjusted by adding an acidic substance such as hydrochloric acid or sulfuric acid, or a basic substance such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or organic amines.

In order to prevent clogging of the ink passage of the writing instrument due to the generation of mold, sodium dehydroacetate is used.
Preservatives and fungicides such as 1,2-benzothiazalin-3-one, methyl-2-benzimidazole carbamic acid ester and sodium benzoate can also be added in appropriate amounts.

Further, in the case of a writing instrument using a metal in a portion that comes into contact with the ink, a corrosion inhibitor such as benzotriazole or ethylenediaminetetraacetic acid can be added to prevent corrosion of the metal.

The ink of the present invention can be obtained by mixing and stirring a pigment which is an essential component, water and an alkyl acrylate-alkyl methacrylate copolymer crosslinked with allylpentaerythritol and / or a salt thereof. Further, if necessary, the mixture may be set in a dispersing machine, and the classification of the coloring material and the defoaming of the ink may be performed by filtration and centrifugation. Further, by performing these steps under reduced pressure, entrapment of bubbles in the ink can be suppressed. As the writing means, as the type of the pen tip, a writing instrument such as a pen-type writing instrument, a writing brush, an air brush, a ballpoint pen, a fiber convergent pen tip, and a synthetic resin pen tip can be used.

[0017]

The aqueous ink of the present invention having an acrylic acid-alkyl methacrylate copolymer crosslinked with allylpentaerythritol and / or a salt thereof as an essential component can be produced without causing precipitation of dye or aggregation of pigment over time. The reason why writing without blurring is possible even after long-term aging is considered as follows.

The cross-linked acrylic acid-alkyl methacrylate copolymer and / or a salt thereof are in the form of a filament that has been shrunk in a coil shape in a dry state and overlapped in a layered form, and has a water content in a state of being dispersed in an aqueous ink. It swells when added to show a thickening effect. Further, when the pH is 5 or more, a part of the carboxyl group in the molecule is dissociated, and the gap between the molecules becomes larger due to the electric repulsion between the negative charges, thereby further swelling and exhibiting a large thickening effect. Since the acrylic acid-alkyl methacrylate copolymer and / or a salt thereof of the present invention is cross-linked, the molecular chains cannot spread indefinitely even when sufficiently swollen. A spherical microgel is formed. The acrylic acid-alkyl methacrylate copolymer and / or a salt thereof have a hydrophilic carboxyl group and a lipophilic alkyl group in the molecule. For this reason, the molecular chain on the outermost surface of the microgel formed in the ink, which is in contact with the hydrophilic solvent, has hydrophilic carboxyl groups on the solvent surface side, and the lipophilicity on the center side of the microgel of the same molecular chain Has a structure in which the alkyl groups of In the second molecular chain from the outside, alkyl groups are arranged on the outside, and carboxyl groups are arranged on the center side of the gel. The third layer from the outside has a layer sandwiched between lipophilic alkyl groups and a layer sandwiched between hydrophilic carboxyl groups, such as carboxyl groups on the outside and alkyl groups on the center of the microgel. Create a structure in which alternates exist. The dye or the pigment dispersed in the ink has a charge. When the electric charge is large, it enters between the hydrophilic layers formed in the microgel, and when the electric charge is small, it enters between the lipophilic layers. Since microgels are microspheres with a three-dimensional network structure in which molecular chains are partially crosslinked, they are difficult to deform due to external forces.
Since the coloring agent that has entered the interlayer formed by molecular chains is not easily affected by disturbance over time unless the gel is broken,
The dye is less likely to be insolubilized and the pigment to be coagulated and settled over time.
Therefore, even after a long period of time, blurring of the handwriting due to insolubilization of the dye and coagulation and sedimentation of the pigment can be suppressed as much as possible. When used with a ballpoint pen, the microgel is broken by the shearing force due to the rotation of the ball, the fluidity is imparted to the ink, and the blurring of the handwriting is further suppressed.

[0019]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. In Examples and Comparative Examples, "parts" means "parts by weight".
Is shown.

The viscosity of each ink is determined by E.
LD viscometer ST adapter 10 rpm measured value (25
° C).

Example 1 Purified water 36.5 parts Ethylene glycol 10.0 parts Glycerin 10.0 parts Microjet M800 (black pigment dispersion, manufactured by Orient Chemical Co., Ltd.) 25.0 parts Proxel GXL (1.2- Benzothiazolin-3-one, manufactured by ICI, UK) 0.2 part 2% aqueous solution of Pemulen TR-1 18.0 parts 25% aqueous sodium hydroxide 0.3 part Of the above components, other than 25% aqueous sodium hydroxide And stirred for 1 hour with propeller stirring. Thereafter, a 25% aqueous sodium hydroxide solution was added, and the mixture was stirred again for 1 hour.
A black ink having a pH of 7.8 and a viscosity of 1500 mPa was obtained.

Example 2 Purified water 18.3 parts Propylene glycol 10.0 parts Glycerin 15.0 parts NKW-2117 (fluorescent pink pigment dispersion, manufactured by Nippon Fluorescent Chemical Co., Ltd.) 40.0 parts Proxel GXL 2 parts 2% aqueous solution of Pemulen TR-2 14.0 parts 25% aqueous lithium hydroxide solution 2.5 parts Among the above components, components other than the 25% aqueous lithium hydroxide solution were mixed and stirred with a propeller stirrer for 1 hour. Then 25%
Add aqueous lithium hydroxide solution and stir again for 1 hour,
A fluorescent pink ink having a pH of 13.5 and a viscosity of 700 mPa was obtained.

Example 3 Purified water 51.7 parts Propylene glycol 15.0 parts Quinacridone red 6.0 parts SMA Resin 1440 (27% styrene-maleic acid copolymer, manufactured by ARCO Chemical, USA) 5.0 parts Proxel GXL 0.2 part 2% aqueous solution of Carbopol ETD 2020 22.0 parts 2-Amino-2-methyl-1,3-propanediol (pH adjuster) 0.1 part Carbopol ETD 2020-2 of the above components %
The components other than the aqueous solution were mixed and subjected to a dispersion treatment with a sand mill for 4 hours. After that, Carbopol ETD 2020-2
% Aqueous solution was added and stirred for 1 hour with a propeller stirrer, and then coarse particles were removed by centrifugation at 8000 G for 1 hour to obtain a red ink having a pH of 5.5 and a viscosity of 2200 mPa.

Example 4 Purified water 35.8 parts Ethylene glycol 10.0 parts Glycerin 10.0 parts Microjet M800 (black pigment dispersion, manufactured by Orient Chemical Co., Ltd.) 25.0 parts Proxel GXL 0.2 parts Pemulen TR-1 2% aqueous solution 18.0 parts Sulfuric acid 1.0 part Among the above components, except for the 25% sodium hydroxide aqueous solution, were mixed and stirred with a propeller for 1 hour. Thereafter, sulfuric acid was added, and the mixture was stirred again for 1 hour, so that the pH was 4.4 and the viscosity was 120 m.
A black ink of Pa was obtained.

Comparative Example 1 Purified water 54.0 parts Ethylene glycol 10.0 parts Glycerin 10.0 parts Microjet M800 25.0 parts Proxel GXL 0.2 parts Guar gum (Sancho Co., Ltd. product) 0.8 parts Among the components, components other than Microjet M800 and guar gum are mixed and stirred with a propeller stirrer. Guar gum was added during stirring, and the mixture was stirred for 2 hours.
800 and stirred for an additional 2 hours until pH 7.5,
A black ink having a viscosity of 1300 mPa was obtained.

Comparative Example 2 Purified water 35.8 parts Ethylene glycol 10.0 parts Glycerin 10.0 parts Microjet M800 25.0 parts Proxel GXL 0.2 parts Rheogic 252L (crosslinked sodium acrylate, Nippon Pure Chemical ( 18.0 parts 25% aqueous sodium hydroxide solution 1.0 part Of the above components, a mixture other than the 25% aqueous sodium hydroxide solution was mixed, and the mixture was stirred with a propeller stirrer for 2 hours. % Aqueous sodium hydroxide solution, and stirred again for 1 hour.
A black ink having a H of 8.0 and a viscosity of 1500 mPa was obtained.

[0027]

The results of the following tests performed on the inks of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

Writing Scattering Test After Aging The inks of Examples 1 to 4 and Comparative Examples 1 and 2 were filled in a refill of a ballpoint pen K105 manufactured by Pentel Co., Ltd. to prepare a sample for a writing test. Was left facing downward at a temperature of 50 ° C. and a humidity of 30% for 3 months. Next, the left sample is brought to room temperature (about 25 ° C.) for 2 hours.
After a while, the temperature of the sample is returned to room temperature, and then JIS
3201 Writing paper TS-4C-
The writing speed was 10 cm, the writing speed was 7 cm / sec, the writing weight was 100 g, and the writing angle was 70 °, and the writing was performed 100 cm. The length of the thin spot in this 100 cm handwriting was measured. The shorter the length of the thread, the less clogging due to sedimentation of the pigment over time,
It can be determined that the ink has been properly discharged.

Test for confirming the dispersion stability of the pigment The same three-month standing test as in Test 1 was carried out at room temperature (about 25 ° C.) for 2 hours, and the temperature of the sample was returned to room temperature. The holding portion was cut off with a cutter, and the first drop coming out of the pen tip and one drop of the inks of Examples 1 to 4 and Comparative Examples 1 and 2 immediately after production were applied to J.
It was applied to IS3201 writing paper and spread evenly and simultaneously with a rubber spatula. In each of the examples and comparative examples, the densities of the spread ink of the sample immediately after preparation and the sample left for 3 months were visually compared. If there is little difference between the concentration of the ink immediately after preparation and the concentration of the sample left for 3 months under the conditions of a temperature of 50 ° C. and a humidity of 30%, the ink is less dispersed in pigment and has excellent dispersion stability.
If the concentration of the sample left for 3 months at 30 ° C. and a humidity of 30% is higher, it can be determined that the ink has a large amount of sedimentation of the pigment and has poor dispersion stability.

[0030]

[Table 1]

As described above, the water-based ink of the present invention can minimize the occurrence of blurring at the time of writing due to the insolubilization of the dye and the coagulation and sedimentation of the pigment even with the lapse of time. The microgel is broken by the shearing force due to the rotation of the ball, the fluidity is imparted to the ink, and the blurring of the handwriting is further suppressed.

Continued on the front page (72) Inventor Yoshiya Ueda 4-1-8 Yoshimachi, Soka-shi, Saitama F-term (reference) in the grass processing plant of Pentel Co., Ltd. 4J039 AD09 AD10 BC07 BE01 BE12 CA03 CA06 EA44 GA27

Claims (2)

[Claims] 1. An aqueous ink for writing implements, comprising at least an acrylic acid-alkyl methacrylate copolymer cross-linked with a colorant, water and allylpentaerythritol and / or a salt thereof. 2. The water-based ink for a ball-point pen according to claim 1, wherein the pH of the water-based ink is 5 or more (25 ° C.).