Jet printing ink composition containing an ethylene oxide adduct of acetylenic diol

An ink composition for use in jet printing comprising an aqueous solution of a water-soluble dye and a humectant consisting of ethylene oxide adducts of at least one acetylenic diol in the absence of any glycol or glycol ether.

The invention relates jet ink and particularly an aqueous jet printing ink 
for printing with a jet ink printing system. 
The principle underlying jet printing with ink is based on driving ink 
through a fine nozzle of metal or glass, so that uniform ink Droplets are 
ejected from the nozzle tip. The ink Droplets are electrostatically 
deflected with a deflecting electrode, arranged in front of the nozzle, so 
that symbols are printed with a preliminarily determined matrix. In this 
printing process the ink in the nozzle is divided in fine ink Droplets and 
the direction of the ink jet is controlled by deflecting plates or through 
nozzle movement. This printing process is highly dependent on the 
properties of the ink. The ink must be capable of forming stable ink 
Droplets under pressure and under an electrical field, which have a high 
deflection sensitivity. Further, the ink must readily emerge from the 
nozzle. In addition, clogging of the nozzle by drying ink must be 
prevented. Commercial nozzle jet inks are divided in aqueous and 
nonaqueous inks. Nonaqueous inks have the disadvantage of low stability 
ink Droplets because of low surface tension. As a result, while in flight 
the ink Droplets form a fog. In addition, such a nonaqueous ink has a high 
electrical resistance and a low deflecting sensitivity. At the same time, 
these ink Droplets are particularly unstable under a high electrical 
charge. Consequently, it has been difficult to print clear and distinct 
symbols with this method. 
The concepts of the present invention reside in a new and improved ink 
composition suitable for use in jet printing comprising an aqueous 
solution of a water-soluble dye and a humectant consisting of ethylene 
oxide adducts of at least one acetylenic diol in the absence of any glycol 
or glycol ether. The preferred ethylene oxide adduct of at least one 
acetylenic diol is the ethylene oxide adduct of 
2,4,7,9-tetra-methyl-5-decyne-4,7-diol. 
It has been found that printing inks formulated in accordance with this 
invention have the desired viscosity for use in jet printing, and that the 
viscosity of the composition is subject to little variation with use as 
water is lost by evaporation during recirculation of the ink composition 
through the jet printer. In addition, the humectant of this invention 
substantially prevents or minimizes tip drying of the printing ink in the 
orifice or nozzle during down time of the printer, such as when the 
printer is shut down over night. 
The total amount of the humectant mixture employed in the ink composition 
of the present invention can be varied within wide limits as dictated by 
the viscosity considerations of the ink composition. 
As the coloring material in the ink composition of the invention, use 
should be made of a water-soluble dye or mixture of dyes. The use of 
pigments or other forms of particulate matter is preferably avoided since 
such materials tend to clog the very small orifice of the jet printer. 
Preferred dyes of the present invention are the commercially available 
direct dyes which generally contain an ionizable inorganic salt, such as 
Glauber salts, or sodium chloride which has been added during manufacture 
in order to standardize the dye lot. The inorganic material thus renders 
the dye conductive whereby the ink jet is capable of being deflected in an 
electromagnetic field during jet printing. Such direct dyes are well known 
to those skilled in the art and are commercially available, as represented 
by the C.I. direct black 38 dyes (e.g., capable of being deflected in an 
electromagnetic field Direct Black GW marketed by the Tenneco Color 
Division of Tenneco Chemicals and Capamine Black ESA marketed by the 
Capital Color and Chemical Co.). Such dyes are available in a number of 
colors, any one or more of which can be used in the practice of the 
invention. If use is made of a pure dye containing no ionizable salt, the 
desired conductivity can be achieved by adding 0.5% ionizable salt, such 
as one of the types described, to the composition. For a further 
description of such well known dyes, reference can be made to the Color 
Index, published by the Society of Dyes and Colorists in cooperation with 
the American Association of Textile Chemists and Colorists (1957). 
The ink composition of the present invention can be prepared by thoroughly 
mixing the components to insure uniform mixing and complete dissolution of 
the water-soluble dye, and then filtering the resulting composition to 
remove any particulate contamination. As will be apparent to those skilled 
in the art, filtration of the composition after mixing the components is 
highly desirable in order to remove from the ink composition particulate 
matter, such as contamination or undissolved dye, which might otherwise 
serve to clog or obstruct the jet of a jet printer during use. It is 
frequently preferred to filter the composition of the invention to remove 
particulate matter having a diameter greater than 2 microns, and 
preferably 1 micron, to insure that obstruction of the jet of the jet 
printer will be avoided. 
The invention is described in the following on the basis of exemplified 
embodiments.

While there are disclosed below but a limited number of embodiments of the 
invention herein presented, it is possible to provide still other 
embodiments without departing from the inventive concepts herein 
disclosed. Various other modifications will be readily apparent to those 
skilled in the art. 
The following novel compositions are expressed in parts by weight: 
EXAMPLE 1 
______________________________________ 
Distilled water 61% 
Ethylene oxide adduct of 
2,4,7,9-tetra-methyl-5- 
decyne-4,7-diol 
(Sold as Surfynol 485 
by Air Products and Chemicals, Inc. 
14% 
Direct Blue dye solution 
C.I. 218 (Sold as 
Pontamine Bond Blue B Liquid 
by E. I. DuPont deNemours & Co.) 
15% 
Direct Black C.I. 38 
(Sold as 
Pontamine Black SP Liquid 
by E. I. DuPont deNemours & Co.) 
10% 
100% 
______________________________________ 
This ink has a viscosity of 3.5 cp. It prints satisfactorily, and has idled 
on and off in the prototype jet printer for six days without clogging. 
Printer startups, after long periods of idling, are immediate. 
EXAMPLE 2 
______________________________________ 
Distilled water 75% 
Ethylene oxide adduct of 
2,4,7,9-tetra-methyl-5- 
decyne-4,7-diol 
(Sold as Surfynol 485 
by Air Products and Chemicals, Inc. 
5% 
Direct Blue dye solution 
C.I. 218 (Sold as 
Pontamine Bond Blue B Liquid 
by E. I. DuPont deNemours & Co.) 
10% 
Direct Black C.I. 38 
(Sold as 
Pontamine Black SP Liquid 
by E. I. DuPont deNemours & Co.) 
10% 
100% 
______________________________________ 
This ink has a viscosity of 2.0 cp.