JPS61271A - Water based ink composition having low electrical conductivity and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled compsn. which has low electrical conductivity, contains water as its main medium and can be used in an electrostatic ink jet system, by bringing a specified water-dispersible ink compsn. into contact with an ion-exchangeable surface. CONSTITUTION:Various cation and anion exchange resins or their moldings are added to a water-dispersible ink compsn. consisting of 1-40% water-insoluble or difficultly water-soluble nonionic dye (e.g. disperse dye) having an average particle size of 5mu of below, 3-100% (based on the quantity of dye) nonionic dispersant (e.g. polypropylene glycol polyethylene glycol ether), 0-40% water- soluble solvent (e.g. glycol), 30-99% water, etc. to bring the ink compsn. into contact with the surface having ion exchangeability, thus obtaining the titled compsn. in which electrical conductivity is lowered to 1X10<-6>S/cm or below. Ion exchange resin particles are mixed with the compsn. to keep low electrical conductivity during the storage of the compsn.

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a low conductivity aqueous ink composition and manufacturing process. (Prior art) Conventionally, water-based inks that use water as the main medium have high electrical conductivity because they use water-soluble ionic dyes, and Urakan Y ink is used for applications that require low electrical conductivity. . Examples of applications where conductivity is specified include inks for electrostatic ink cartridges and recording ink cartridges 1 to 11d. Literature in this field [e.g., Gutter [1 et al., 14th Imaging Engineering Conference/7 Lens]

``Ink ejection characteristics for inkjet printers'' by Kanatsu et al., Institute of Electronics and Communication Engineers EMC83-151 - Development of color ink for inkjet printers'' (1983), the preferable electrical conductivity is 10-9 to 10-78/cm. thing,
Is water-based ink high in electricity? +(10-I S , ycm about r9F,) (7)/l is disclosed to be suitably f. (Problems to be Solved by the Invention) The present invention provides an aqueous ink composition that can be used in an electrostatic inkjet in a water-soil medium. (Means for Solving the Problems) (1) Contains a nonionic dye and a nonionic dispersant that are insoluble or poorly soluble in water, and contains 1
A water-based ink composition having a low conductivity of 10-6 S/cm or less (at 25°C). (2) At least insoluble or poorly soluble in water + 1
A water-dispersed ink composition containing an ionic dye and a non-ionic dispersant is contacted with an ion-exchangeable surface to form a 1×1
A method for producing an aqueous ink, characterized by reducing the conductivity to 0-6877 cm or less (25°C). Hereinafter, the content of the present invention will be explained in detail. The dyes of the present invention include commonly used water-soluble anionic dyes that are insoluble or poorly soluble nonionic dyes;
Alternatively, cabionic dyes have high conductivity (not suitable). Suitable dyes for the present invention include those that do not have these anionic groups or cationic groups, such as disperse dyes, vat dyes, and oil-soluble dyes.Structure of the dye is optional.However, commercially available dyes that contain a large amount of 7-ion dispersants have high conductivity as an aqueous solution, which is undesirable.
, it is necessary to use a pure dye from which f-axis substances have been removed as much as possible. The pure dye of the present invention is insoluble or sparingly soluble in water, and it is necessary to use a dispersant to avoid fine dispersion when preparing aqueous ink. It is necessary to use a dispersant as long as it can disperse the dye.
Its structure is in question. . Examples of these include known -JI: ion active angle agents such as -j;
-L, polyAxy] nitrogen alkyl door,
Polyoxyethylene fatty acid nitrogen, poly/1-1-
1F Renzurbitan fat i! f I Thrill, Porin゛(]] Pirengri] - Rupoly L Direngrini 1ru 1-
Examples include Ral Sentence n. In particular, polypropylene resin 1- which is said to be a pull D nick type
A nonionic bamboo activator having a polycyclic structure such as a hydrophobic group or a hydrophobic group has a high dispersion effect and is preferably used. In the present invention, in addition to the dye and the dispersant, it is preferable to add a solvent such as water-soluble Grinyls, and an agent for adjusting physical properties such as surface tension and viscosity. The conductivity of the water-based ink of the present invention is 1×1O-6s,'cm
(25°C) or below. According to the investigation conducted by the present inventors, the aqueous ink obtained from a nonionic dye, a nonionic dispersant, and pure water using a normal method has a conductivity of around 10"S/cn, and the above-mentioned slit 5゜4 (Fengming et al. this water ↑!t ink on the ion-exchangeable surface E, ig)'I'J! In particular, L and 'ri, which match dispersion stability: < I
Q'-6 or less low conductivity ink is applied, electrostatic type for slitting, 1 to 1, etc., ink for T to 1 ink, 1, (R1) J susceptibility is good f< It was found that 19. The upper limit of the electrical conductivity is not particularly limited, but the electrical conductivity of pure water is 6.3X10-"S,'Cl'l
, '-d3, even when mixed with a low conductivity solvent, 1
It is difficult to obtain an aqueous ink with a molecular weight of 0-9 or less.
1 to 40% dispersant 3 to 100% to aqueous dye 111 solvent 0 to 40% water Preferably, the ink has a composition of 30 to 99%.Physical properties such as viscosity and surface tension may be adjusted as appropriate depending on the application. Ru. From the viewpoint of dispersion support bamboo, the particle size of the dye is on average 5μ or more, preferably on average 2μ or less. Applications of the aqueous ink of the present invention include, for example, ink for electrostatic ink printing, such as slitting, printing, printing, etc., but of course it is not limited to these. Next, the method for producing the ink of the present invention will be described. According to the studies conducted by the present inventors, even if fractional IJ is performed using purified nonionic dye, dispersant, and pure water, l
A low conductivity ink of X10-6 or lower, that is, a 10-7 level, cannot be obtained, and is at most a 10-5 level. The inventors used such an ink once prepared as an ink. It has been found that a low electrical conductivity of 10-t level can be obtained relatively easily by contacting a surface with a conductivity of 10-t. According to the study by unexploited town names, θY is better (is 1 even during preservation).
．． Contact with ion exchange surfaces should be avoided. This is -E
This is because the power outage rate gradually increases by placing ink whose conductivity is at the 10-7 level in the IJ. Therefore, the ink of the present invention can be prepared by introducing an ion exchange material such as ion exchange resin particles into the ink during storage.
It is preferable that tj <. The ion exchange material used in the present invention is not particularly limited, and various known cation and anion exchange resins and molded products made from them can be used. Next, in the present invention, for the purpose of adjusting conductivity, preventing drying, preventing freezing, etc. Rice water-soluble 11 solvent can be added. The solvent to be added preferably has an electrical conductivity equal to or lower than that of water. For example, 1, alcohols such as ethanol and isopropyl alcohol, 1.33 zotanyls, hexylene glycols, glycols such as propylene glycols, and propylene glycols. Examples include glycol derivatives such as pyrene glycol 1-rumetyl 1-fluor and pyrene glycol 1-fluor. <Example> Example 1 8 parts of non-ionic supernatant 1, C, 1, F-wispers and knot 60 washed with pure water, 8 parts of Plu [1 Nick F-68 (Jl!J) as a dispersant. Non-iΔ manufactured by Denka Co., Ltd.
4 parts (50% counter-staining agent), 9 parts ion-exchanged pure water
2 parts were pulverized and dispersed using Santocou) ink,
A disperse dye ink with an average particle size of 0.9 μm was obtained. The conductivity of this ink is 25°C-CI, 3x 10-” S/c
…Met. To this ink, 20 parts of ion exchange resin Amberlite MB-2 resin (manufactured by Rohm and Haas) particles were added, and 3
Stir for hours. The conductivity of the ink with 1q is 5,2
x 1 (significantly lowered to 1-78y'am. When ion exchange resin was added to this ink and left as IJ for one week, it was 6.3X10-7 S, -'cm) Low conductivity 2. Those that retain the ion exchange resin are 3. lX1O-(i has electrical conductivity of 10-yy
There was a sh'r. When this was tested using a slit-type ink jet tester, the low conductivity ink of the example was found to be in a good jetting state, but the ink that was not treated with the ion-exchange resin was The ink smear occurred and the casting condition was poor. Although this ink is suitable for printing on paper, it has been found to be suitable for use in inkjet dyeing of polynisple fabrics. Example 2 Dyeing El binding-CC, 1, Disverse Et c+-5
4 parts of Pluronic [108] as a dispersant, 20 parts of hexyl 1, non-glycyl, 1-l, and 68 parts of ion-exchanged pure water were dispersed in the same manner as in Example 1, and using an ion-exchange resin. When processed, 7.4X 10 7 S
An aqueous ink with a low conductivity of ,,/am was obtained. Example 3 As a dye, 10 parts of C,1, Solvent Blue 83,
Dispersion and ion exchange were performed in the same manner as in Example 1 using 6 parts of Pull 1 Conic F--68 as a dispersant and 84 parts of ion-exchanged pure water, and the conductivity was 4.3 x 10-7.
A low conductivity ink of S/cm was obtained. (Effects of the Invention) The ink of the present invention enables water-based ink to be used in fields that require low conductivity, where conventionally only oil-based inks could be used.
One major advantage is that there are no environmental hygiene issues such as irritation or odor. The dye ink of the present invention can be applied to paper [r'l copy [,
C can be preferably used for dyeing.

Claims (2)

[Claims] (1) Contains a nonionic dye that is insoluble or poorly soluble in water and a nonionic dispersant, and has an electrical conductivity of 1 x 10^-
A low conductivity aqueous ink composition having a conductivity of ^6S/cm or less (25°C). (2) A water-dispersible ink composition containing at least a nonionic dye that is insoluble or poorly soluble in water and a nonionic dispersant is brought into contact with an ion exchange surface,
A method for producing an aqueous ink, characterized by reducing the conductivity to 6 S/cm or less (25° C.).