JPH0120669B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ink for an ink-type wire dot printer that moves ink adhered to the wire surface forward by sliding the wire back and forth, and transfers the ink adhered to the wire surface to a printing medium. 2. Description of the Related Art Printers such as thermal printers and wire dot printers are known as printers used for computer output recording, facsimile, and the like. Among these, wire dot printers include ribbon-type wire dot printers that print by striking an ink ribbon with a wire.The ink adhering to the wire surface is moved forward by the sliding movement of the wire back and forth, and the ink adhering to the wire surface is printed. Ink-type wire dot printers that transfer images onto a medium are known. Due to the mechanism of this ink-type wire dot printer, the ink is exposed to the air at the printer head, so the ink tends to evaporate. After the printer gradually dries, when you try to resume operation, you will find that 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. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ink for an ink-type wire dot printer, which prevents ink from drying in the printer head as much as possible, and enables smooth initial printing after the printer has been stopped for a long period of time. There is a particular thing. In order to obtain the desired ink, the inventor of the present invention has finally completed the present invention as a result of detailed examination of the mechanism of an ink-type wire dot printer and the composition and materials of the ink that is compatible with it. The present invention comprises a water-soluble dye; a water-soluble organic solvent; water; one or a mixture of two or more selected from polyvinyl alcohol, polyvinylpyrrolidone, and polyoxyethylene; urea and/or a derivative thereof; Viscosity at 25℃ is 3-12
The gist of this article is an ink for ink-type wire dot printers characterized by centipoise (cp), surface tension of 32 dyne/cm or more, and PH of 7 or more. The present invention will be explained in detail below. The water-soluble dye used in the present invention has a pH of 7.
Those above are preferable and are soluble in water, such as direct dyes,
Acidic dyes, food colorants, etc. are suitable, and specific examples include Direct Deep Black XA (similar to CI Direct Black 38), Kayaku Direct Deep Black EX (CI Direct 38), Kayaku Direct Fast Black (CI Direct 51), Water black L200 (same as
19), Direct Fast Black AB (32),
Direct Fast Black B (22), Kayaku Direct Brilliant Yellow G (CI Direct Yellow 4), Eisen Primula Yellow 5GLH (same)
26), Eisen Primula Yellow GCLH (44), Direct Fast Yellow R (50), Kayaku Direct Scarlet B (CI Direct Red 37),
Eisen Direct Fastread FH (same 1),
Eisen Primula Scarlet GSH (same 4), Eisen Direct Rodulin Red BH (same)
31), Eisen Primula Red 4BH (81), Direct Fast Scarlet 4BS (23), Kayaku Direct Scarlet 3B (39), Eisen Primula Pink 2BLH (75), Kayaku Direct Sky Blue 6B (CI Direct Blue 1), Eisen Direct Sky Blue 5BH (15), Mitsui Direct Blue 2BN (6), Kayaras Splat Turquoise Blue FBL (199), Water Blue #3 (86), Kayaras Blue Gconc (78), Direct dyes such as Kayarasu Spura Blue FF2GL (106), Nigrosine (CI acid black 2), Suminol Milling Black 8BX (24), Kayanor Milling Black VLG (26), Suminol Milling Black NB (29) , Eisen Opal Black WH (52), Water Black 187-
L (154), Fast Yellow (CI Assisted Yellow 9), Mitsui Assisted Fast Yellow G (17),
Suminol Leveling Yellow NR (19), Water Yellow #1 (23), Suminol Fast Yellow R (25), Metanyl Yellow (36), Water Yellow #6 (42), Suminol Fast Stretch
GG (CI Acid Orange 19), Naphthol Orange (CI 20), Suminol Milling Orange R (CI Acid Orange R)
45), Water Orange #18 (56), Solar Red RB (CI Assisted 7), Solar Rubin (14), Newcoccin (18), Acidrhodamin G (50), Erythrosin (51), Kayaqua Shitsurodamine FB (52), Water Red #2 (87), Water Pink #2 (52)
92), Eisen Rose Bengal (94), Suminol Brilliant Scarlet DH (97), Mitsuiashi Violets 6BN (CI Assits Violets 15), Mitsuiashi Violets BN (CI Assits)
17), Patent Blue V (CI Acid Blue 1),
Patent Blue AF (7), Water Blue #9 (9), Water Blue #116 (15), Orient Solble Blue OBC (22), Mitsui Nylon Fast Blue G (25), Suminol Fast Blue Acidic dyes such as 3G (27), Daiwa Digo Carmine (74), Water Blue #115 (90), Orient Soluble Blue OBB (93), Acid Brilliant Milling Green B (CI Acid Green 9) , Sunset Yellow (C.
I. Food Yellow 3), Amaranth (CI Food Red 9), Food Grade Green No. 2 (CI Food Green 2)
There are food colorants, such as, which can be used singly 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 0.5 to 20% by weight based on the total amount of ink. The water-soluble organic solvent used in the present invention is used for the purpose of preventing ink drying and promoting dye dissolution, and specific examples include ethylene glycol, propylene glycol,
1.3-butanediol, diethylene glycol,
Polyhydric alcohols and their derivatives such as triethylene glycol, tetraethylene glycol, dipropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, dimethyl cellosolve, diglyme, glycerin, methyl carbitol, carbitol, Formamide, dimethyl sulfoxide, tetrahydrofurphthalyl alcohol, tetrahydrofurandimethanol, diacetone alcohol, 2-pyrrolidone,
N-methyl-2-pyrrolidone, 4-butyrolactone, sulfolane, thiodiethanol, monoethanolamine, diethanolamine, triethanolamine, ethylene carbonate, propylene carbonate, morpholine, 1-(2-hydroxyethyl)-piperazine, etc. It can be used as a seed or a mixture of two or more types, and the amount used is preferably 5 to 40% by weight based on the total amount of the ink. The amount of water used as the main solvent is based on the total amount of ink.
40-80% by weight is desirable. 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, tetramethyl urea, thiourea, and ethylene oxide adducts to urea, and the amount used is based on the total amount of ink.
20% or less is preferable. In addition, polyvinyl alcohol, polyvinylpyrrolidone, and polyoxyethylene used in the present invention are mainly used for the purpose of adjusting the viscosity of ink, and by adding small amounts of these water-soluble polymers, water-soluble organic It is now possible to adjust the viscosity to 3 to 12 cp without using a large amount of solvent, and prevents the problem that it takes a long time for the printed image to dry, which occurs when adjusting the viscosity by using a large amount of water-soluble organic solvent. becomes possible. 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. The ink of the present invention is prepared by appropriately selecting, mixing, and dissolving the above-mentioned ink components.As for the physical properties of the ink, it is necessary to adjust the viscosity to 3 to 12 cp at 25°C. This is because when printing is less than 3 cp, the head temperature is around room temperature at the beginning of printing, the ink comes out smoothly, and clear printing is possible, but as printing continues, the head temperature rises and the ink viscosity decreases. Therefore, too much ink comes out, and when the wire collides with the printing medium, the ink scatters around the dots, resulting in a disadvantage that the printing becomes smudged. Also, if it is 12 cp or more,
Because the ink does not move smoothly from the ink-impregnated material to the wire, the ink does not cover the entire tip of the wire, making it impossible to print clearly. Furthermore, it is necessary to adjust the surface tension of the ink to 32 dyne/cm or higher. When the ink is set to 32 dyne/cm or less, the ink penetrates well into the printing medium (especially paper), so it dries quickly on the printing medium, which is preferable as a printer ink. This makes it unsuitable as an ink for wire dot printers that require fine print. Furthermore, the ink of the present invention needs to have a pH of 7 or higher. This is because if the pH is below 7, the metal parts used in the printer head will corrode over time. Hereinafter, the present invention will be explained in more detail according to examples, and in the examples, "parts" indicate "parts by weight." Example 1 (Black ink) Kayaku Direct Deep Black EX (Nippon Kayaku
Co., Ltd., CI Direct Black 38) 7.0 parts Water Elo #1 (Orient Chemical Co., Ltd., CI Direct Yellow 23) 0.3 parts Kuraray Poval 124 (10% aqueous solution) (Kuraray Co., Ltd. polyvinyl alcohol) 6.0 parts Ethylene glycol 10.0 parts Thiodiglycol 7.0 parts Diethylene glycol 1.0 parts Urea 5.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.2 parts Water 63.5 parts After mixing each of the above components and stirring at 40 to 50°C for 3 hours, viscosity 4.2cp, surface tension
A black ink of 55 dyne/cm and pH 9.4 was obtained. Example 2 (yellow ink) Eisen Primula Yellow 5GLH (manufactured by Hodogaya Chemical Co., Ltd.,
CI Direct War 26) 3.0 parts Water Erotic #2 (manufactured by Orient Chemical Co., Ltd., CI
Food Yellow 3) 1.0 part polyvinylpyrrolidone K=30 (10% aqueous solution)
15.0 parts Ethylene glycol 10.0 parts Thiodiglycol 7.0 parts Triethanolamine 1.0 parts Ethylene urea 2.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.1 parts Water 60.9 parts The above ingredients were mixed and stirred at 40-50°C for 2 hours. After that, it is filtered to separate the impurities, and the viscosity is 5.7cp,
A yellow ink with a surface tension of 53 dyne/cm and a pH of 9.8 was obtained. Example 3 (Red ink) Eisen Primula Pink 2BLH (Hodogaya Chemical Co., Ltd.)
(manufactured by CI Direct Red 75) 1.0 part Eisen acid Phloxin PB (Hodogaya Chemical Co., Ltd.)
4.0 parts ethylene glycol 5.0 parts thiodiglycol 10.0 parts PEO-15 (1% aqueous solution) (manufactured by Steel Chemical Industry Co., Ltd., polyoxyethylene) 10.0 parts urea 2.0 parts sodium pentachlorophenol (10 parts) % aqueous solution) 0.1 part water 67.9 parts The above ingredients were mixed, stirred at 40-50℃ for 2 hours, filtered to separate impurities, and the viscosity was 4.7 cp.
A red ink with a surface tension of 51 dyne/cm and a pH of 8.3 was obtained. Example 4 (Blue ink) Water Blue #3 (manufactured by Orient Chemical Co., Ltd., C.
I. Direct Blue 86) 4.0 parts Ethylene glycol 14.0 parts N-methyl-2-pyrrolidone 5.0 parts Ethylene urea 10.0 parts Kuraray Poval 124 (5% aqueous solution) 25.0 parts Sodium pentachlorophenol (10% aqueous solution) 0.1 part Water 41.9 parts Above After mixing each component and stirring at 40-50℃ for 3 hours, the viscosity was 7.7cp and the surface tension was
A blue ink of 57 dyne/cm and pH 8.8 was obtained. Comparative Example 1 (Black ink) 5.0 parts of urea was removed from the ink composition of Example 1,
When black ink was mixed by adding 5.0 parts of water instead, an ink with a viscosity of 4.1 cp, a surface tension of 56 dyne/cm, and a pH of 9.3 was obtained. Comparative Example 2 (Yellow ink) When 15.0 parts of polyvinylpyrrolidone K = 30 (10% aqueous solution) in the ink composition of Example 2 was changed to 2.0 parts, 13.0 parts of water was added instead to form a yellow ink.
An ink with a viscosity of 2.2 cp, a surface tension of 51 dyne/cm, and a pH of 10.0 was obtained. Comparative Example 3 (Red ink) 10.0 parts of PEO-15 (3% aqueous solution) was used instead of 10.0 parts of PEO-15 (1% aqueous solution) in the ink composition of Example 3.
When red ink was blended using
An ink with a surface tension of 51 dyne/cmPH of 8.3 was obtained. Comparative Example 4 (Blue ink) The ink composition of Example 4 was added with Florado FC-430.
(Fluorine-based surfactant, manufactured by Sumitomo 3M Ltd.) 0.2
When blue ink was mixed with
A blue ink with a surface tension of 7.7 cp, a surface tension of 28 dyene/cm, and a pH of 8.8 was obtained. 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.

【table】

[Table] ○: Good △: Slightly problematic ×: Poor Evaluation was performed as follows. Drying of head: After printing, the head was left indoors for 3 days without a cover, and then printing was performed again and the print quality was visually judged. Smear resistance, scratch resistance, and splatter resistance: Visually judge the image quality of the printed test pattern (characters, symbols). From the above results, the ink of the present invention is optimal as an ink for ink type wire dot printers.

Claims (1)

[Claims] 1 A water-soluble dye; a water-soluble organic solvent; water; one or a mixture of two or more selected from polyvinyl alcohol, polyvinylpyrrolidone, and polyoxyethylene; urea and/or its derivative; at 25°C. An ink for ink-type wire dot printers characterized by a viscosity of 3 to 12 centipoise, a surface tension of 32 dyne/cm or more, and a pH of 7 or more.