JPH0345752B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ink for an ink-type wire dot printer that moves the ink attached to the wire surface forward by sliding the wire back and forth, and transfers the ink attached to the wire surface to a printing medium.
More specifically, the present invention relates to an improved ink for ink-type wire dot printers that has excellent quick-drying properties and is less likely to cause unevenness on paper, especially when printed with multiple colors of ink. An ink-type wire dot printer uses the back-and-forth sliding movement of a wire to move the ink adhered to the wire surface forward and transfer the ink adhered to the wire surface to the printing medium. Unlike wire dot printers, the ink is introduced into the printer head in a liquid state, allowing for relatively free selection of the ink's physical properties, color tone, etc., which allows the printing quality and color tone to be changed freely. Suitable for color printing. However, due to the structure of ink-type wire dot printers, the printer head is connected to the printing surface (paper).
Since the printer head must be installed very close to the paper, the distance between the tip of the printer head and the paper is only about 0.2 to 0.7 mm, and if the surface of the paper is uneven, the printer head will rub against the paper, resulting in smeared prints. A problem arises. This problem rarely occurs when characters are printed once in a single color, but when two or more types (colors) of ink are printed in the same position multiple times, color printing is performed using the subtractive color mixing method. When printing (color printing), the next ink is printed before the first ink has completely dried, resulting in unevenness in the printed area, which often occurs when printing by mixed colors. In addition, because of the mechanism of ink-type wire dot printers, the ink is exposed to the air at the printer head, which tends to cause ink to evaporate. It has been known that the wire gradually dries in the head and when you try to restart the operation, the wire becomes difficult to move and solid ink is deposited on the head, making it difficult to print smoothly at the initial stage. . Therefore, attempts have been made to use aliphatic polyhydric alcohols and their derivatives as wetting agents for the purpose of suppressing drying of the ink, but although the drying of the ink can be suppressed to some extent, the printer is not operated for more than two days. When left for a long time, ink solids were observed to be deposited on the head, and the initial printing when operation was resumed was extremely unstable. Therefore, the first object of the present invention is to provide an ink-type wire dot printer that is suitable for color printing using the subtractive color mixing method, which dries quickly and does not cause irregularities on paper due to continuous printing in the same position. The objective is to obtain commercial ink. A second object of the present invention is to provide an ink-type wire dot printer which prevents ink from drying in the printer head as much as possible and allows smooth initial printing after the printer has been stopped for a long period of time. The purpose is to obtain ink. The present inventor has finally completed the present invention after studying various water-soluble organic solvents in order to obtain the desired ink. That is, the present invention provides an ink for ink-type wire dot printers comprising at least a water-soluble dye, a water-soluble organic solvent, water, and urea and/or a derivative thereof, wherein the water-soluble dye is an acid dye and/or a direct dye. and the water-soluble organic solvent has a saturated vapor pressure at normal temperature of more than 0.1 mmHg and 50 mmHg or less, and a boiling point at normal pressure of 75°C to 200°C,
Furthermore, the present invention is directed to an ink for ink-type wire dot printers, characterized in that the amount of the water-soluble organic solvent used is 20% by weight or less based on the total amount of the ink. In the present invention, it is important that the water-soluble organic solvent satisfies the conditions described above. This is because ink that uses a water-soluble organic solvent with a saturated vapor pressure at room temperature of 0.1 mmHg or less and a boiling point of 200°C or more at normal pressure causes unevenness on the paper because the solvent evaporates slowly in the printed area after printing. In addition, water-soluble organic solvents with a saturated vapor pressure at normal temperature of more than 50 mmHg and a boiling point of 75° C. or less at normal pressure are likely to evaporate, causing ink to dry in the printer head. Furthermore, if the amount of water-soluble organic solvent used exceeds 20% by weight based on the total amount of ink, the amount of solvent per unit area of the printed area will increase, causing unevenness on the paper surface. The present invention will be explained in detail below. The water-soluble dyes used in the present invention include direct dyes and/or acid dyes, and specific examples include Japanol Fast Black D Conc (CI Direct Black 17), Water Black 100L (CI Direct Black 19), Water Black L-200 (same as
19), Direct Fast Black B (22), Direct Fast Black AB (32), Direct Deep Black EX (38), Direct Deep Black XA (similar to 38), Direct Fast Black Conc (51), Kayaras Spragley VGN (71), Kayaku Direct Brilliant Yellow G (CI Direct Yellow 4), Direct Fast Yellow 5GL (26), Eisen Primula Yellow GCLH (44), Direct Fast Yellow R (50), Eisen Direct Fast Stretched
FH (CI Direct Red 1), Nippon Fast Scarlet GSX (4), Direct Fast Scarlet 4BS (23), Eisen Direct Rodulin BH (31), Direct Scarlet B (37), Kayaku Direct Scarlet 3B
(39), Eisen Primula Pink 2BLH (75),
Sumilight Red F3B (80), Eisen Primula Red 4BH (81), Kayaras Spralvin BL
(83), Kayaras Light Red F5G (225), Kayaras Light Red F5B (226), Kayaras Light Rose FR (227), Direct Sky Blue
6B (CI Direct Blue 1), Direct Sky Blue 5B (CI Direct Blue 15), Sumilight Splat Blue BRR
Conch (71), Daibogen Turquoise Blue S (86), Water Blue #3 (86), Kayara Turquoise Blue GL (86), Kayara Spra Blue FF2GL (106), Kayara Spra Blue
Direct dyes such as FFRL (108), Kayaras Splat Turquoise Blue FBL (199), Acid Blue Black 10B (CI Acid Black 1), Nigrosine (2), Suminol Milling Black
8BX (24), Kayanor Milling Black VLG
(26), Suminoru Fast Black BR Conch (31), Mitsui Nylon Black GL (52), Eisen Opal Black WH Extra Conch (52), Suminoor Black WA (52), Ranil Black BG Extra Conch (52) 107), Kayanor Milling Black TLB (109), Suminol Milling Black B (109), Kayanor Milling Black TLR (110), Eisen Opal Black New York (119), Water Black
187-L (154), Kayaku Acid Brilliant Flavin FF (CI Acid Yellow 7:1), Kayashi Yellow GG (17), Xylene Light Yellow 2G140
% (17), Suminol Leveling Yellow NR (same)
19), Daiwa Tartrazine (23), Kayaktatrazine (23), Suminol Fast Yellow R (23)
25), Diamond Light Yellow 2GP (29), Suminol Milling Yellow O (38), Suminol Milling Yellow MR (42), Water Yellow #6
(42), Kayanor Yellow NFG (49), Suminol Milling Yellow 3G (72), Suminol Fast Yellow G (61), Suminol Milling Yellow G (78), Kayanor Yellow N5G (72) 110), Suminol Milling Yellow 4G200% (141), Kayanor Yellow NG (135), Kayanor Milling Yellow 5GW (127), Kayanor Milling Yellow
6GW (142), Sumitomo Asto Scarlet A
(CI Assisted Red 8), Kayak Silk Scarlet (CI 9), Solar Rubin Extra (CI Assisted Red 8)
14), Daiwani Yukokushin (18), Eizen Ponceau RH (26), Daiwa Red No. 2 (27), Suminol Leveling Brilliant Red S3B (27)
35), Kayacyl Rubinol 3GS (37), Eisenerythrosin (51), Kayakuashi Rhodamine FB (52), Suminol Leveling Rubinol
3GP (57), Diamond Alizarin Rubinol
F3G200% (82), Ekinshi (87), Water Pink #2 (92), Crampsaid Phloxin PB (92), Rose Bengal (94), Kayanor Milling Scarlet FGW (111), Kayanor Milling Rubin 3BW (129), Suminor Milling Brilliant Red 3BN Conch (131),
Suminol Milling Virile Retread BS (same)
138), Eisen Opal Pink BH (186), Suminol Milling Brilliant Retard B Conch (249), Kayaku Ashit Brilliant Retded
3BL (254), Kayaku Ashit Brilliant Red BL (265), Kayanor Milling Red GW
(276), Mitsuiasu Violet 6BN (CI
Assisted Violet 15), Mitsui Biolent BN (17), Sumitomo Patent Pure Blue VX (CI Assisted Blue 1), Water Blue #106 (1), Patent Blue AF (7), Water Blue # 9 (9), Daiwa Blue No. 1 (9), Supranor Blue B (15), Orient Soluble Blue-OBC (22), Suminol Leveling Blue 4GL (23), Mitsui Nylon Fast Blue G ( 25), Kayasil Blue AGG (40),
Kayasil Blue BR (41), Mitsui Alizarin Saphyllose SE (43), Suminol Leveling Sky Blue R Extra Conc (62), Mitsui Nylon Fast Sky Blue B (78), Sumitomo Brilliant Indocyanine 6Bh/c ( 83),
Sandrancyanine N-6B350% (90%), Water Blue #115 (90%), Orient Soluble Blue OBB (93%), Sumitomo Brilliant Blue 5G (103%), Kayanor Milling Ultra Sky SE (112%) , Kayanol Milling Cyanine 5R
(113), Eisen Opal Blue 2GLH (113), Eisen Opal Blue 2GLH (113)
158), Daiwa Guinea Green B (CI Acid Green 3), Acid Brilliant Milling Green B (CI 9), Daiwa Green #70 (CI 16), Kayanol Cyanine Green G (CI 25), Suminol Milling Green G Examples include acidic dyes such as (27). These direct dyes and acid dyes can be used alone or as a mixture of two or more, and the amount used can be varied depending on the printing density and printing medium, but is preferably 1.0 to 20% by weight based on the total amount of ink. As mentioned above, water-soluble organic solvents can be used as long as they have a saturated vapor pressure at normal temperature of more than 0.1 mmHg and less than 50 mmHg, and a boiling point at normal pressure of 75°C to 200°C. Specific examples are given below. and ethylene glycol, methyl cellosolve, ethyl cellosolve, ethyl cellosolve isopropyl ether, butyl cellosolve, diethyl cellosolve, monoglyme, diglyme, diethyl carbitol, methyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether , polyhydric alcohols and their derivatives such as methyl cellosolve acetate, ethyl cellosolve acetate, ethanol, n-propanol, iso-propanol, n-butanol,
Alcohols such as sec-butanol, iso-butanol, tert-butanol, tetrahydrofurfuryl alcohol, diacetone alcohol, chloroethanol, amines such as dipropylamine, dibutylamine, monoethanolamine, morpholine, cyclohexanone, monoacetin, dimethyl These water-soluble organic solvents include formamide and the like, and these water-soluble organic solvents can be used alone or as a mixture of two or more. As mentioned above, the amount of the water-soluble organic solvent used must be 20% by weight or less based on the total amount of the ink. The amount of water used as the main solvent is preferably 50% by weight or more based on the total amount of ink. Urea and/or its derivatives used in the present invention are mainly used for the purpose of promoting dye dissolution and preventing drying in the printer head.
When used in combination with a water-soluble dye and a water-soluble organic solvent, it exhibits a particularly remarkable effect in preventing drying in the printer head.
Specific examples of urea and its derivatives that can be used in the present invention include urea, ethylene urea, thiourea, and ethylene oxide adducts to urea, and the amount used is preferably 20% or less based on the total amount of the ink. In addition to the above ingredients, various anionic and /or Penetrants such as nonionic surfactants are used at 3% by weight or less based on the total amount of the ink, and formalin, phenol, pentachlorophenol, and dehydroacetic acid are used to prevent ink flow inhibition due to mold growth and ink decay. A small amount of a preservative and fungicide such as sodium may be added as appropriate. Furthermore, when the ink comes into contact with metal parts, anticorrosive agents such as benzotriazole and ethylenediaminetetraacetate may be added as necessary to prevent metal corrosion. Rust agents can also be added as appropriate. In addition, as necessary, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, poly(methyl vinyl ether), methyl cellulose,
Water-soluble polymers such as hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, and gelatin can also be added, and if these water-soluble polymers are used,
The viscosity can be adjusted to an appropriate value without using a large amount of water-soluble organic solvent, and the problem that occurs when adjusting the viscosity using a large amount of water-soluble organic solvent is that it takes a long time to dry the printed image. It becomes possible to prevent this. The ink of the present invention is prepared by appropriately selecting, dissolving, and mixing the above-mentioned ink components, and as for the physical properties of the ink, it is preferable to adjust the viscosity to 12 cp or less at 25°C. This is because if it is 12 cp or more, the ink will not move smoothly from the ink-impregnated material to the wire in the head, and the ink will not cover the entire tip of the wire, making it impossible to print clearly. Hereinafter, the present invention will be explained in detail based on Examples. In the Examples, "part" indicates "part by weight", "P" indicates "saturated vapor pressure at 25 ° C.",
"bp" indicates "boiling point at normal pressure". Example 1 (Yellow ink) Daiwa Tartrazine (manufactured by Daiwa Kasei Co., Ltd., CI Acid Yellow 23) 5.0 parts ethylene glycol (P = 0.12 mmHg, bp =
197.3℃) 10.0 parts Urea 7.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.1 part Benzotriazole (corrosion inhibitor) 0.4 parts Sodium hydroxide (25% aqueous solution) 0.1 part HPC(H) (1% aqueous solution) (Japan) Hydroxypropyl cellulose (manufactured by Soda Co., Ltd.) 20.0 parts Water 57.4 parts 100.0 parts The above ingredients were mixed and stirred at 20 to 25°C for 3 hours, then mixed into paper (No. 2 manufactured by Toyo Paper Co., Ltd.). Impurities were separated by filtration to obtain a yellow ink with a viscosity of 5.2 Cp. Example 2 (Magenta ink) Suminol Milling Brilliant Red B Conc (manufactured by Sumitomo Chemical Co., Ltd., CI Assured Red 249)
3.5 parts Ethylene glycol 10.0 parts Urea 7.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.1 part Benzotriazole 0.4 parts Sodium hydroxide (25% aqueous solution) 1.5 parts HPC(H) (1% aqueous solution) 20.0 parts Water 57.5 parts 100.0 An ink was prepared from each of the above components in the same manner as in Example 1 to obtain a magenta ink with a viscosity of 5.2 Cp. Example 3 (Cyan ink) Water Blue #3 (manufactured by Orient Chemical Industry Co., Ltd.,
CI Direct Blue 86) 4.5 parts Acid Brilliant Milling Green B (manufactured by Hodogaya Chemical Co., Ltd., CI Acid Green 9) 0.5 parts Tetrahydrofurfuryl Alcohol (P=0.8mm
Hg, bp=178℃) 5.0 parts Ethylene glycol 5.0 parts Urea 5.0 parts Water 80.0 parts Total 100.0 parts An ink was prepared in the same manner as in Example 1 using each of the above components to obtain a cyan ink with a viscosity of 3.2Cp. . Example 4 (Black ink) Water Black L-200 (20% solution) (manufactured by Orient Chemical Industry Co., Ltd., CI Direct Black 19)
25.0 parts Water Yellow #6 (for complementary colors) (Orient Chemical)
(Manufactured by Kuraray Co., Ltd., CI Acid Yellow 42) 0.3 parts Ethylene glycol 15.0 parts Urea 8.0 parts Sodium hydroxide (25% aqueous solution) 0.1 part Kuraray Poval 124 (10% aqueous solution) (Manufactured by Kuraray Co., Ltd.,
Polyvinyl alcohol) 7.0 parts Water 44.6 parts Total 100.0 parts An ink was prepared in the same manner as in Example 1 using each of the above components to obtain a black ink with a viscosity of 4.3 cP. Comparative Example 1 (Example containing high boiling point solvent) Kayasil Yellow GG (manufactured by Nippon Kayaku Co., Ltd., CI Acid Yellow 17) 4.0 parts ethylene glycol 10.0 parts thiodiglycol (bp = 282°C) 10.0 parts glycerin (bp = 290°C) 10.0 parts Urea 10.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.1 parts Water 55.9 parts 100.0 parts An ink was prepared from each of the above components in the same manner as in Example 1 to obtain a yellow ink with a viscosity of 3.4 cP. Comparative Example 2 (Example containing a low boiling point solvent) Kayaku Ashido Brilliant Red 3BL (Nippon Kayaku Co., Ltd. CI Ashido Red 254) 1.5 parts Water Pink #2 (manufactured by Orient Chemical Industry Co., Ltd.,
CI Acid Drops 92) 2.5 parts ethylene glycol 10.0 parts methanol (bp=64.5°C) 5.0 parts urea 10.0 parts sodium hydroxide (25% aqueous solution) 0.3 parts water 70.7 parts 100.0 parts Using the above ingredients, prepare in the same manner as in Example 1. Ink was made and magenta ink with a viscosity of 3.2Cp was obtained. Comparative Example 3 (Example containing 20% or more of solvent) Water Blue #3 4.0 parts Water Blue #9 (manufactured by Orient Chemical Industry Co., Ltd.,
CI acid blue 9) 0.2 parts ethylene glycol 25.0 parts monoethanolamine (P=0.59mmHg, bp=
170.95℃) 2.0 parts Urea 5.0 parts Metrose 90SH-15000 (1% aqueous solution) (Shin-Etsu Chemical
Co., Ltd., Hydroxypropyl Methyl Cellulose)
10.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.1 parts Water 53.7 parts 100.0 parts An ink was prepared in the same manner as in Example 1 using each of the above components to obtain a cyan ink with a viscosity of 4.8 Cp. Comparative example 4 (Ink not containing urea) Water black #100-L (20% solution) (manufactured by Orient Chemical Industry Co., Ltd., CI Direct Black
19) 35.0 parts Daiwa Green #70 (manufactured by Daiwa Kasei Co., Ltd., CI Acid Green 16) 0.3 parts Kuraray Poval 124 (10% aqueous solution) 7.0 parts Ethylene glycol 15.0 parts Monoethanolamine 3.0 parts Sodium pentachlorophenol (10%) Aqueous solution) 0.1 part Sodium hydroxide (25% aqueous solution) 0.2 part Water 39.4 parts 100.0 parts An ink was prepared from the above components in the same manner as in Example 1 to obtain a black ink with a viscosity of 5.2 Cp. The inks of Examples 1 to 4 and Comparative Examples 1 to 4 were used in an ink type wire dot printer to print and evaluate the inks. The results are shown in the table below.

[○: Printing paper has no unevenness and is in good condition. △: There are unevenness on the printing paper, but there is no printing stain. ×: The printing paper has unevenness and the head rubs the paper, staining the printing. ]

From the above results, the ink of the present invention is optimal as an ink for ink type wire dot printers.

[Brief explanation of drawings]

FIG. 1 shows a printing pattern by a wire dot printer for determining the state of paper after printing according to the present invention, where 1 indicates a dot and 2 indicates a portion that is not printed.

Claims (1)

[Claims] 1. An ink for ink-type wire dot printers comprising at least a water-soluble dye; a water-soluble organic solvent; water; and urea and/or its derivatives,
The water-soluble dye is an acid dye and/or a direct dye, and the water-soluble organic solvent has a saturated vapor pressure at room temperature.
greater than 0.1 mmHg and less than 50 mmHg, and
An ink for an ink-type wire dot printer, characterized in that the boiling point at normal pressure is 75°C to 200°C, and the amount of the water-soluble organic solvent used is 20% by weight or less based on the total amount of the ink.