Opaque jet ink compositions

The present invention relates to non-pigmented jet ink compositions and to a method of producing opaque coded messages therewith. The compositions comprise, on a weight basis, between 2 and 15% of a gellable cellulose ester having a hydroxyl content of from 2 to 8%, from 1.5 to 15% of a binding agent selected from the group consisting of alkali soluble rosin type and maleic type resins, polyvinyl acetate resins, and acrylic resins, and a solvent blend, the blend consisting essentially of an organic solvent system and a non-solvent, said non-solvent comprising from 2 to 10% by weight of the ink composition. Preferred solvents are methanol, acetone, methyl ethyl ketone and ethyl acetate, while the preferred non-solvent is water. Upon evaporation of the solvent blend, the resultant dry films scatter light incident thereto whereby the opaque images are produced. In a particularly preferred embodiment, a hygroscopic salt is included in the composition as an opacity enhancement agent.

FIELD OF INVENTION 
This invention relates to non-pigmented jet ink compositions that dry 
opaque, particularly to compositions that dry opaque white, or opaque 
yellow, and to their application onto non-porous substrates. The ink 
compositions, which are suitable for use in high speed jet ink printing 
systems, contain a cellulose ester film former and a resin binder in a 
solvent blend. It is believed that the resulting film, obtained upon 
evaporation of the solvent blend, has a reticulated structure containing a 
multiplicity of microvoids, the microvoids scattering light incident 
thereupon, whereby the white opaque image is produced. 
BACKGROUND OF THE INVENTION 
Jet ink printing systems discharge discrete droplets of ink through a fine 
jet nozzle to the substrate. In this method of printing, unlike letter 
press, gravure, silk screen and comparable printing techniques, there is 
no contact between the printer and article to be printed. The ink droplets 
have a defined resistivity so that they can be deflected by an electric 
field when discharged from the nozzle. The jet ink printing system is of 
considerable importance in applying decorative and identifying indicia to 
a variety of substrates, including glass, metal and synthetic polymeric 
surfaces. U.S. Pat. Nos. 3,465,350 and 3,465,351 are exemplary of these 
systems. 
Ink to be used with jet printing means have specific viscosity and 
resistivity limitations, should provide good wettability of the substrate, 
and must be quick drying and smear resistant. Further, the ink must be 
compatible both with the jet printing equipment and in the eventual end 
use application. With regard to the former it is critical that the ink 
flow through the fine jet nozzles without clogging same. 
Typically, jet inks consist of three basic components--a colorant such as a 
dye or pigment; a resin binding agent which serves to secure or adhere the 
colorant to the substrate surface, and a carrier fluid or solvent for the 
colorant or binding agent, the carrier fluid evaporating upon application 
of the ink. In jet printing inks, an electrolyte is often employed to 
ensure that the droplets can be adequately charged whereby proper 
deflection is achieved. U.S. Pat. No. 4,021,252 issued to Banczak et al is 
representative of this genre of jet printing inks. Banczak uses from one 
to 25% by weight shellac as the binding agent, between 0.5 and 5% by 
weight of a basic dye as the colorant, and a solvent blend consisting of 
water and alcohol. Optionally the solvent blend may be modified by the 
addition of a glycol ether to solubilize colorants of limited solubility. 
Other prior art patents reflective of the Banczak approach are listed 
below, some of which are for specific end use applications: 
______________________________________ 
U.S. Pat. No. 4,024,096 
Wachtel 
4,070,322 Hwang et al 
4,155,767 Specht et al 
4,155,895 Rohowetz et al 
4,168,254 Fell 
4,168,662 Fell 
4,177,075 Mansukhani 
4,186,020 Wachtel 
4,196,006 Mansukhani 
4,196,007 Mansukhani 
German Offenlegungsschrift 
28 12 364 M&T Chemicals 
(Published 
October 1978) 
______________________________________ 
To produce an opaque white image utilizing the ink formulations of the 
above identified prior art references, it would be necessary to use a 
pigment such as rutile titanium dioxide. However, this opacifying agent is 
present in the solvent as a dispersed solid, and tends to settle out of 
solution thereby clogging the jet nozzle. This drawback is even more 
pronounced in low viscosity jet inks which are preferred. Other 
disadvantages of conventional pigmented inks are that they usually require 
curing at elevated temperatures, and/or have extended drying times. The 
goal of the present invention, then, is to provide non-pigmented jet inks 
that produce opaque white images on non-porous substrates, and which can 
be applied to said substrates in a single operating step. 
As is well known in the art, a solution of certain compounds, particularly 
the cellulose esters, when applied to a surface will dry opaque white. See 
generally, Jerome Seiner, Microvoids As Pigments. A Review, Industrial and 
Engineering Chemistry, Product Research & Development, Vol. 17, pp. 
302-317 (Dec. 12, 1978) and J. J. Clancy, Microvoid Coatings in Graphic 
Art Application. A Patent Survey, Industrial and Engineering Chemistry, 
Product Research & Development, Vol. 13, No. 1, pp. 30-34 (March 1974). A 
sampling of patents issued with respect to such compositions follows: 
______________________________________ 
U.S. Pat. No. 1,449,157 
Wilkie 
2,296,337 Cummings 
2,519,660 James 
2,739,909 Rosenthal 
2,927,039 Vander Weel 
3,020,172 Mohnhaupt 
3,031,328 Larsen 
3,654,193 Seiner 
3,655,591 Seiner 
______________________________________ 
The above inventions are related to paints, paper coatings, and recording 
materials. 
More recently, U.S. Pat. No. 4,207,577 to Mansukhani applied this 
technology to jet inks. The Mansukhani patent discloses a two-step 
procedure for obtaining opacity, the second step being either an 
adjustment of the temperature of the applied film to the ambient dew 
point, or by applying moisture thereto. In an alternate embodiment a basic 
dye is used in the ink formulation, the film then being moistened with 
water. The method above is applied to a general ink composition consisting 
of cellulose esters, binding agents and a solvent blend. The two step 
approach of Mansukhani represents a serious limitation in the use of his 
ink in certain applications. For example, some products are sensitive and 
can not undergo the second "moisturing" step. Other products are humidity 
sensitive. Similarly, printing on a hot surface will drive off the 
solvents before the second step can be accomplished. Finally, the 
Mansukhani method requires the addition of a second step treatment zone to 
existing product conveying systems. 
SUMMARY OF INVENTION 
It is an object of this invention to provide improved non-pigmented jet ink 
compositions, suitable for use with jet ink printing techniques, that 
provide opaque films. 
It is another object of this invention to provide improved non-pigmented 
jet ink compositions that dry opaque white and which are suitable for use 
on metal, glass and other non-porous substrates. 
Yet another object of this invention is to provide a jet ink that dries 
opaque white which has good stability and shelf life. 
A related aspect of this invention is to provide a method for obtaining 
substrates having identifying indicia, said indicia derived by application 
of the jet ink compositions of the present invention by means of jet ink 
printing techniques. In this regard, the indicia as applied to non-porous 
substrates exhibit ready adhesion thereto, are abrasion and fade 
resistent, and can withstand post application conditions of moisture and 
elevated temperature. 
It is a primary object of this invention to obtain substrates having said 
identifying indicia by means of a one step method not involving a post 
cure treatment of the film to render it opaque. 
A further object of the invention is to provide a method for reconstituting 
cycled ink used in the printing operation. 
These and other objects of the invention will be better understood from a 
reading of the detailed description of the invention, a summary of which 
follows. 
The jet ink formulations disclosed herein comprise a film forming cellulose 
ester having a hydroxyl content between 2 to 8%, a resin binding agent, 
and a solvent blend. Preferred cellulose esters are cellulose acetate 
propionates, cellulose acetate butyrates and cellulose acetates, while the 
binding agent may be selected from a wide range of alkali soluble resins 
of the rosin ester and maleic types as well as polyvinyl acetate and 
acrylic resins. The solvent blend consists essentially of at least one 
volatile organic solvent within which the film forming cellulose ester is 
soluble in combination with one or more non-solvents of reduced volatility 
within which the film forming cellulose ester is essentially insoluble, 
and which is miscible with the organic solvent. Volatile components of the 
solvent blend comprise from about 70 to 90% by weight of the ink 
composition, and are selected from the group consisting of aliphatic 
alcohols of one to three carbon atoms, ketones of three to seven carbon 
atoms, and acetates of four to seven carbon atoms. The non-solvent is 
present in concentration from about 2 to 10% by weight of the ink 
composition, the preferred non-solvent being water. 
In use, the ink is fed from a supply reservoir to the nozzle of the jet 
printing apparatus and then dispensed as a coded series of droplets onto 
the substrate. Evaporation of the solvent blend from the droplets is 
achieved rapidly, the indicia turning opaque thereupon. Because the amount 
of ink actually printed is quite small, most printers transfer ink from 
the supply reservoir in a larger, more controllable volume, apply only the 
small quantity needed to the substrate, and send the excess to a return 
tank. However, the entire flow of ink from the supply reservoir discharges 
through the nozzle at atmospheric conditions, the resulting flash 
vaporization causing a change in the cycled ink composition present in the 
return tank. For this reason it is preferred to reconstitute the cycled 
ink with make-up solution consisting essentially of the organic solvent, 
but also including if necessary non-solvent and ink solids. The make-up 
ink is formulated specifically to re-attain approximately the supply 
reservoir composition for subsequent re-use of the cycled ink. 
DETAILED DESCRIPTION OF THE INVENTION 
The non-pigmented jet ink compositions of the present invention contain a 
film forming cellulose ester, a resin binding agent and a solvent blend 
therefor hereinafter described. The composition may optionally contain 
other ink solids such as dyes, optical brighteners, surfactants, 
hygroscopic salts, and electrolytes. As used herein, pigment and dyes 
comprise the class of compounds defined as colorants. Pigments, generally 
being insoluble, dry powers, are incompatible with the invention; dyes, 
typically being soluble organic compounds, may be included to provide 
enhanced visibility of the opaque image on a particular substrate. 
Each of the primary constituents must be in proper proportion to achieve 
both suitability for the jet ink printing apparatus and for coating a 
particular substrate. To meet these use requirements, the following 
standards should be attained: 
(1) inks should dry essentially instantly or be smear resistant upon 
application with subsequent complete drying in about 60 seconds, 
preferably in less than 30 seconds, without a post cure; 
(2) ink viscosity should be between from about 1.5 to about 25 centipoise, 
preferably between 1.5 and 18 centipoise; 
(3) indicia printed on glass must exhibit ready adhesion thereto, be 
abrasion and fade resistant, and have the ability to withstand conditions 
of moisture and elevated temperature encountered generally during 
conventional pasteurization operations; 
(4) as applied to metal or synthetic polymer coating surfaces, the indicia 
must exhibit resistance to fading and be able to maintain adhesion under 
pasteurization conditions when immersed in an aqueous solution for 15 
minutes at 150.degree. F.; 
(5) indicia printed on bottles must exhibit resistance to removal by 
lubricant soaps conventionally used by commercial bottlers on conveying 
lines, and 
(6) inks should have a minimum shelf life of about one month. 
Fade resistance as used herein means that indicia should remain opaque on 
the substrate for a period of not less than three months. Shelf life is 
defined as the ability of the ink itself to render opaque white films upon 
use after storage at ambient conditions for no less than one month. 
COMPONENTS OF THE COMPOSITION 
Investigations into the many film formers, the large array of binding 
agents, and the broad spectrum of solvent species and concentrations that 
can be hypothecated by a reading of the prior art revealed that the 
aforesaid properties of the ink, the characteristics of the indicia, and 
the one-step approach to film formation could be achieved only with the 
proper combination of compatible prime constituents. Thus, for example, 
adhesion to the substrate was poor unless the proper resin were used. The 
selection of resin, however, was a function of solvent blend employed and 
film former chosen. The ability to form an opaque film was likewise 
dependent on the compatibility of the constituents. Similarly, suitable 
shelf life was obtained by using the appropriate solvent blend--film 
former--resin ingredients. 
The Film Former and Binding Agent 
The film former used in the ink composition must be a cellulose ester whose 
percent hydroxyl content ranges from between 2.0% to about 8.0%, 
preferably between 4.0% to 6.0%. The ester is present in concentrations 
from about 2.0 to 15.0% by weight of the composition, preferably from 
between 3.0 to 10.0% by weight of the ink formula. It is critical that the 
film former be gellable in the non-solvent as will be more extensively 
described below. Hence, while the film former is soluble in the volatile 
organic solvent constitutents of the solvent blend, it is essentially 
insoluble in the less volatile non-solvent. Furthermore, the ink system 
should have a viscosity between 1.5 to 25 cp., preferably between 1.5 and 
18 cp. at the ester concentrations stated above for use with jet printing 
equipment. Preferred film formers are cellulose acetate propionate, 
cellulose acetate butyrate, cellulose acetate and combinations of same, 
each having a preferred hydroxyl content between 4.0 and 6.0% of the 
ester, and are available commercially from Eastman Chemical Company. 
The resin binding agent is used to improve the adhesion of the film to the 
substrate. It is believed that the ester film has a planar structure 
providing few sites for attachment to a surface. The binding agent 
apparently provides molecular projections which attach to the substrate. 
One class of appropriate binding agents are rosin based ester resins or 
maleic resins soluble in the ink solvent system and also soluble in the 
non-solvent. Dissolution of these resins in the non-solvent in many 
instances is enhanced by a somewhat basic environment. Therefore, it is 
often preferred to adjust the pH of the ink to between 8 and 9 when they 
are used by the addition of an effective amount of dilute ammonium 
hydroxide or the equivalent. Examples of such compounds are Alresat KM140, 
a rosin modified maleic anhydride resin (American Hoescht); UniRez 757, a 
maleic resin (Union Camp), and Filtrez 5001, a fumaric rosin based resin 
(FRP Company). 
Preferred binding agents that can be used are polyvinyl acetate resins, 
acrylic type resins, and their copolymers. Commercially available resins 
of this type are Synthacryl VSC 75/1, an acrylic resin (American Hoescht); 
Gelva #264 and Gelva #V1 1/2, polyvinyl acetate resins (Monsanto), and 
NS26-1314, a carboxylated polyvinyl acetate resin copolymer (National 
Starch). As with the rosin and maleic resins, the preferred resins should 
be soluble in the ink solvent, and should also be soluble in water or 
dilute alkali solutions. In commercial form many of these binding agents 
themselves are in solution, the solvents therefor necessarily being 
compatible with the ink itself. 
The binding agent is present in the ink composition in an amount between 
1.5 to 15% by weight, although the preferred range is between 2 and 8% by 
weight. Necessarily, the agent must be compatible with the cellulose ester 
film former, and generally has a viscosity in a 50% by weight solution of 
dilute aqueous alkali of less than 15,000 cps., preferably less than 2000 
cps. The melting point should be above 150.degree. F. Binding agent 
percentages stated herein are on a resin solvent free basis. 
The Solvent Blend 
In the description of the solvent blend, the following definitions are 
employed: 
Solvent Blend--the mixture of a more volatile solvent and a less volatile 
non-solvent. 
Solvent--the more volatile portion of the solvent blend within which the 
film former and resin is soluble. Where more than one solvent is used, the 
term solvent system has been employed. Non-solvent--the less volatile 
portion of the solvent blend within which the film former is essentially 
soluble. 
The solvent blend consists essentially of at least one or more volatile 
solvents and at least one less volatile non-solvent. The amount of solvent 
in the blend must be sufficient to completely dissolve the film former 
notwithstanding the diminution of solvating power of the blend by the 
addition of non-solvent thereto. Its volatility should be such that 
substantial evaporation of the solvent takes place rapidly, preferably 
within 2 to 3 seconds, upon application of the ink composition to the 
substrate. However, the solvent must also be compatible with the jet ink 
printer. For example, ethers such as ethyl ether have been found to be 
suitable solvents yet are not preferred because they are incompatible with 
gaskets and seals typically used in the printing equipment and form 
dangerous reaction products with oxygen. Another requirement of the 
solvent is that it should evaporate uniformly from the film former and 
binder. That is, the solvent should be present in solution with the 
non-solvent and dissolved solid constituents throughout the initial 
evaporation period and at least until the onset of gellation as will 
hereinafter be described. 
Conversely, the non-solvent, which is present in concentration ranging 
between 2 and 10% by weight of the composition, should be less volatile so 
that the non-solvent remains subsequent to the evaporation of the solvent. 
Of course, the rate of evaporation of individual constitutents of the 
blend will be dependent on their relative volatilities, and as evaporation 
takes place the solvent blend will become increasingly non-solvent rich. 
It is also preferable that the solvent blend constitutents not form an 
azeotrope that will solubilize the film former. 
Water is the preferred non-solvent, although glycerin has also been found 
to be a suitable substitute. Water is preferred not only because it forms 
the desired gel with the film former, but also because its viscosity is 
low relative to its vapor pressure. Thus, when used in proper amounts, the 
viscosity of the ink composition ranges between 1.5 and 25 cp. as noted 
above. 
Solvents acceptable for use in the blend are aliphatic alcohols having from 
one to three carbons, aliphatic ethers having from four to ten carbons, 
aliphatic ketones of three to seven carbons, and aliphatic acetates of 
three to seven carbons, none of which form an azeotrope that will dissolve 
the film former. In addition, two or more solvents can be combined within 
the blend, and such combinations are preferred in balancing the 
volatility, viscosity, density and resistivity properties of the ink 
composition. For example, methanol is a suitable solvent. However, solvent 
systems comprising methanol-acetone, methanol-methyl ethyl ketone, and 
methanol-acetone-methyl ketone have been found more effective. Similarly, 
the methanol-ethyl acetate and methanol-acetone-ethyl acetate solvent 
systems have been used with success. Generally, however, alkyl acetates 
and ketones should not be present in amounts above about 50% by weight of 
the solvent. As parameters for achieving a usable solvent system for 
incorporation into the solvent blend, it is desirable for the relative 
drying time of the solvent system to be in the range between one and nine 
as compared with ethyl ether having an arbitrary drying time of 1.0 (quick 
drying), and for the viscosity to be between from about 0.2 and 1.2 cp. 
Preferably, the ink composition contains at least 30% by weight methanol. 
The remaining solvent blend constituents are, as a weight percent of the 
ink composition, preferably between 20 and 50% acetone, from 0 to about 
25% methyl ethyl ketone, and from 0% to about 25% ethyl acetate. The 
solvent system is between 70% and 90% by weight of the ink composition. 
The solvent blend, including nonsolvent and solvent, in combination with 
the film former and the binding agent, comprises the ink composition, 
except for minor concentrations of miscellaneous additives hereinafter 
described. 
Other Ingredients 
In general the resistivity of the ink should be between 100 and 3500 
ohm/cm., preferably between 500 and 2000 ohm/cm. In some instances the 
solvent blend or the resin binding agent used will satisfy this 
requirement. However, electrolytes can be added optionally to maintain the 
specific resistivity of the ink within desired limits for use in video jet 
printing equipment. Satisfactory compounds include dimethylamine 
hydrochloride, sodium propionate, sodium acetate, and the like. In 
addition, it has been found that the addition of a hygroscopic salt and 
preferably a deliquescent salt such as dimethylamine hydrochloride or 
lithium chloride in an amount between 0.05 and 3.%, preferably between 0.1 
and 1.0%, by weight of the composition also enhances the opacity of the 
dried film. Hence, such hygroscopic/deliquescent salts are the preferred 
electrolytes, and may be included even though the resistivity is within an 
acceptable range without their addition. 
Finally, small amounts, generally no more than 2.0% each by weight, of 
conventional basic dyes, surfactants, and optical brighteners, can be 
included in the composition. A dye is useful when a white image does not 
show up clearly on a particular substrate. However, the film produced is 
still opaque, and relies on the mechanism described below for visibility. 
Particularly advantageous dyes for use herein are yellow. Typical yellow 
dyes are Morfast Yellow 101, an azo-type dye and Morfast Yellow 102, a 
metal-complexed azo-type dye, both available from Morton-Norwich Company. 
The above dyes are supplied as a 50% solution, with isopropanol as the 
solvent. When used, these dye solutions typically comprise 0.5% to 4% by 
weight of the ink composition. 
Another acceptable yellow dye is Neozapon Yellow GG, also a metal-complexed 
azo-type dye, available from BASF Wyandotte Company. 
MECHANISM FOR PRODUCING WHITE OPAQUE IMAGES 
It is believed that the following events take place to form the film which 
produces the opaque images. 
Upon deposition of the ink on the substrate, the solvent blend evaporates 
rapidly. Because of the difference in relative volatility between the 
solvent and non-solvent, the cellulose ester film former and binding agent 
remain behind in a progressively non-solvent rich residuum of the solvent 
blend. As the concentration of non-solvent increases, the film former, 
which is insoluble in the non-solvent, forms a gel with but a portion of 
the remaining solvent blend. The surplus of solvent blend not entrapped 
within the gel is present as microdroplets amid the gel. Upon subsequent 
complete evaporation of the solvent blend, now principally the non-solvent 
species therein, a reticulated film is produced over the substrate, the 
microdroplets having produced a network of microvoids both within and on 
the surface of the film, said microvoids scattering incident light thereby 
making the film opaque. 
USE OF THE INK COMPOSITION 
A continuous stream of ink is transferred from a pressurized supply 
reservoir for discharge as droplets from a printing nozzle at ambient 
conditions. The pressure in the reservoir is sufficient to overcome 
transfer line and nozzle pressure drops, said pressure being about 10 to 
50 psia. The disposition of the droplets exiting the nozzle is dependent 
on whether a coded message is to be printed on a substrate. Assuming that 
the coded message is not to be printed, the droplets are recaptured 
proximate to the nozzle and cycled back to a return tank. Because the 
nozzle discharges to atmosphere, it is necessary that the return tank be 
under vacuum, the return tank pressure being about 4-6 psia. 
When an article to be encoded passes beneath the printer nozzle, a portion 
of the droplet stream is deflected by a pre-set series of electric signals 
thereby causing the coded message to be printed. The bulk of the droplets, 
however, continue to be recaptured for transfer to the return tank. This 
system is used because the actual amount of ink necessary for printing the 
coded messages is substantially smaller than the volumetric flow rate 
through the printing equipment required for meaningful control. Droplets 
applied to the substrate turn opaque rapidly, generally within a few 
seconds, by means of the mechanism postulate above. 
Make-Up Solution 
Because of the flash vaporization which occurs at the nozzle, and the 
reduction in pressure in the return tank, the composition of the ink in 
the return tank is different than the ink in the supply reservoir. For 
this reason it is necessary to reconstitute the former for eventual re-use 
by the addition of make-up solution. The make-up formulation is a function 
of the rate of loss of the ink constituents, and consists essentially of 
the volatile solvent species, but may also include non-solvent and ink 
solids. In general, make-up is added intermittently. The return tank is 
mounted on a weigh scale, and as evaporation occurs, an automatic valve is 
actuated to allow make-up solution to be transferred from a make-up 
reservoir to the return tank. Alternately, a property of the ink could be 
monitored, e.g., specific gravity, to actuate the transfer. Because the 
rate of loss is dependent upon the actual ink composition and operating 
conditions, the make-up solution composition should be determined a priori 
by a trial and error procedure.

The examples below further illustrate the teachings of this disclosure: 
EXAMPLE 1 
The ink formulation which follows was used successfully to print white 
opaque videojet codes on glass and black cable: 
______________________________________ 
pbw 
______________________________________ 
Cellulose Acetate Propionate 
Film Former 4.32 
(Eastman CAP 504-0.2) 
Polyvinyl Acetate Binding Agent: 
(Monsanto Gelva #264) 
Resin 2.14 
Ethanol 2.61 
Methanol Solvent 86.4 
Water Non-Solvent 4.32 
Dimethylamine Hydrochloride 
Electrolyte; 
0.20 
(DMA.HCl) Opacifier 
Total 
99.99 
______________________________________ 
The use of cellulose acetate propionate has been found to be the most 
preferred film former of those tested. Publication No. E-169D from Eastman 
indicates that CAP 504-0.2 has the following properties: 
______________________________________ 
Viscosity 0.2 seconds (ASTM D-1343 with 
Formula A, D-817) 
Specific Gravity 
1.263 25.degree./4.degree. C. 
Melting Range 188-210.degree. C. 
Hydroxyl Content 
5.0 wt. % (avg.) 
Propionyl Content 
40.0 wt. % (avg.) 
Acetyl Content 2.5 wt. % (avg.) 
______________________________________ 
Gelva #264 is a vinyl type resin whose viscosity is between 7000 and 11000 
cps. in a 55-57% ethanol solution by weight. For computing solvent blend 
constituent concentrations, the resin solvent should be taken into 
account. Conversely, resin concentrations defined herein are on a dry 
basis. 
The ink produced according to this formulation had a Brookfield viscosity 
of 4.0 centipoises at 24.5.degree. C. and a resistivity of 800 ohm/cm. at 
24.5.degree. C. 
EXAMPLE 2 
In this example, the solvent comprises a mixture of methanol and acetone, 
the acetone being used to reduce the viscosity of the ink composition. 
______________________________________ 
pbw 
______________________________________ 
Cellulose Acetate Propionate 
(Eastman CAP 504-0.2) 
Film Former 8.0 
Acrylic Resin (American 
Binding Agent: 
Hoescht Synthacryl VSC 75/1) 
Resin 2.8 
Isopropanol 2.8 
Water 1.4 
Methanol Solvent 40.0 
Acetone Solvent 50.0 
Water Non-Solvent 6.0 
Dimethylamine Hydrochloride 
Electrolyte; 0.2 
Opacifiers 
Total 111.20 
______________________________________ 
This composition has a Brookfield viscosity of 6.11 centipoises at 
24.5.degree. C., and produced a smear resistent printed code about two 
seconds after application to the substrate. 
______________________________________ 
EXAMPLE 3 
pbw 
______________________________________ 
CAP 504-0.20 7.0 
Synthacryl VSC 75/1 
6.0 
Methanol 44.5 
Acetone 26.5 
Methyl Ethyl Ketone 
9.0 
Water 5.8 
Surfactant 1.0 
DMA.HCl 0.2 
Total 100.0 
______________________________________ 
The Brookfield viscosity was 5.6 cps. and the resistivity was 800 ohm-cm., 
each at 24.5.degree. C. This ink was life tested and produced opaque 
images upon use after 1000 hours of storage at ambient conditions. 
In conjunction with the use of this ink on the jet printing apparatus, the 
following make-up solution was employed: 
______________________________________ 
ml. (25.degree. C.) 
______________________________________ 
Acetone 1425 
Methanol 1110 
Methyl Ethyl Ketone 
230 
Ink (as stated above) 
234 
2999. 
______________________________________ 
EXAMPLES 4-9 
Table I provides further examples of the use of cellulose acetate 
propionate in combination with various resin compounds and solvent blends. 
TABLE I 
__________________________________________________________________________ 
Example No. 
Constituent, pbw 
4* 5 6 7 8 9 
__________________________________________________________________________ 
CAP504-0.2 
60 6.0 6.0 8.0 7.0 4.5 
Binding Agent: 
Resin 60 Resin 5.0 
Resin 2.4 
Resin 2.6 
Resin 2.4 
Resin 2.0 
Ethanol 3.6 
Isopropanol 0.4 
Isopropanol 
Ethanol 2.5 
Water 4.0 
Water 1.2 
(Rosin modified 
(Maleic resin, 
(Carboxylated 
(Acrylic resin, 
(Syntharcyl 
(Gelva #264) 
maleic resin, 
UniRez 7083, 
polyvinyl 
Acrysol 1-100, 
VSC 75/1) 
Alresat KM140, 
Union Camp 
acetate, 
Rohm and Haas) 
American Hoescht) 
Corp.) NS-26-1314, 
National 
Starch) 
Methanol 805 82.0 84.0 40.0 57.5 85.5 
Acetone 30.0 
MEK 20.0 
Ethyl Acetate 25.0 
Water 65 7.0 5.0 6.0 4.0 4.5 
DMA.HCl 0.2 0.5 
Optical Brightener 
15 
(Hm-35, DayGlo 
Corp.) 
Surfactant 
20 1.0 0.5 
(FC 170C, 3M Corp.) (FC 170C) 
(Arquad 2C-75, 
Armak Chemicals) 
Dye 2 
(Yellow GG, BASF 
Wyandotte) 
TOTAL, pbw 
1027 100.0 101.0 111.2 100.5 99.5 
__________________________________________________________________________ 
*Sufficient NH.sub.4 OH to raise pH to 8.5 
EXAMPLE 10 
This ink composition shows the use of cellulose acetate butyrate, which has 
a hydroxyl content of 4.3%. 
______________________________________ 
pbw 
______________________________________ 
Cellulose Acetate Butyrate 
6.0 
(Eastman CAP 533-0.4) 
Acrylic Resin (Synthacryl 
7.0 
VSC 75/1) 
Methanol 45.0 
Acetone 20.0 
Methyl Ethyl Ketone 9.0 
Water 7.0 
DMA.HCl 0.2 
Total 94.2 
______________________________________ 
The examples above are intended to be illustrative only, and are not to be 
construed as in any way limiting the invention defined by the claims which 
follow.