Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-02-19
2001-01-23
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S386000, C106S031850, C106S031860
Reexamination Certificate
active
06177498
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to ink-jet inks, and, more particularly to ink-jet inks containing latex polymers having improved print properties.
BACKGROUND ART
Ink-jet inks have recently been developed that utilize latex polymers to achieve smearfastness. Examples of such latex polymers are disclosed in, for example, application Ser. No. 09/120,046, filed Jul. 21, 1998. Examples of such latex polymers used in formulating ink-jet ink compositions are disclosed in, for example, Ser. No. 09/120,270, also filed Jul. 21, 1998. Both applications are assigned to the same assignee as the present application.
There are two types of such latex polymers disclosed and claimed. The first type is referred to as durable core/shell polymers and are given by the formula
[(A)
m
(B)
n
(C)
p
(D)
q
(E)
r
]
x
(I)
wherein A, B, C, D, and E represent functionalities as follows:
A=at least one hydrophobic component contributing to improved durable, film-forming properties selected from moieties which, when homo-polymerized to a solid state, have a glass transition temperature (T
g
) in the range between −150° C. to +25° C.;
B=at least one hydrophobic and solvent barrier moiety used to adjust the T
g
of the hydrophobic component of the polymer (I) which, when homo-polymerized to a solid state, has a T
g
greater than +25° C.;
C=at least one hydrophilic component, selected from a wide variety of water-soluble monomers (optional);
D=at least one UV absorber (optional);
E=a moiety having at least one highly polar functional group (optional);
m=5 to 95 wt %;
n=5 to 95 wt %;
p=0 to 60 wt %;
q=0 to 50 wt %;
r=0 to 40 wt %;
m+n+p+q+r=100 wt %; and
x=1 to 100,000.
Preferably, the final T
g
of the polymer(s) (I) is within the range of about −25° to +110° C., and more preferably, the final T
g
is within the range of about −15° to +90° C., and most preferably within the range of about −10° to +75° C.
The molecular weight (weight average) of polymer (I) is between about 1,000 and 2,000,000, preferably between about 5,000 and 500,000, and most preferably between about 10,000 and 70,000.
Either the C moiety or the E moiety must be present in the polymer to provide a polymer having either a hydrophilic portion or a highly polar portion. Alternatively, one or more surfactants may be used in conjunction with polymer (I), whether in the presence or the absence of the C or E, or both, moieties. The surfactant(s) may be anionic, cationic, non-ionic, or zwitterionic.
The second type of latex polymers is referred to as primer core/shell polymers, which also have a hydrophilic portion and a hydrophobic portion and have the following general structure given by formula (II)
[(A)
m
(B)
n
(C)
p
(E)
r
]
y
(II)
wherein A, B, C, and E are as described above and where m, n, and r are as follows:
m=0 to 90 wt %, preferably 10 to 60 wt %, and more preferably 15 to 50 wt %;
n=0 to 90 wt %, preferably 10 to 60 wt %, and more preferably 15 to 50 wt %;
p=0 to 90 wt %, preferably 10 to 60 wt %, and more preferably 15 to 50 wt %;
r=0.01 to 100 wt %, preferably 0.01 to 60 wt %, and more preferably 1 to 40 wt %;
m+n+r=100 wt %; and
y=1 to 100,000, preferably 10 to 10,000, and more preferably 100 to 1,000.
Preferably, either m or n is non-zero.
The T
g
of the primer core/shell polymers is within the range of about −100° to +100° C., preferably within the range of about −25° to +25° C., and more preferably within the range of about 0° to +25° C.
The molecular weight (weight average) of polymer (II) is between about 100 and 2,000,000, preferably between about 1,000 and 500,000, and most preferably between about 5,000 and 300,000.
These latex polymers, though good for smearfastness, are difficult to print. The printability concerns stems from one or more of the following factors. Because of their partial solubility, these polymers could hinder the bubble nucleation, growth, and ejection process and also could dry fast in the orifice. Essentially, because of their bulky nature, they collect at the interface during nucleation and firing of the droplet, thus hindering the firing. By “printability” is meant any or all of the foregoing: start-up, drop ejection, decap and high frequency firing above 10 kHz. By “start-up” is meant when the pen first starts to fire, the ease with which it fires all nozzles, i.e., the amount of “spitting” required before all nozzles are active. By “drop ejection” is meant the degree of straight drops whose characteristics do not change with (1) time, (2) amount of firing, and (3) frequency. By “decap” is meant the ability of the pen to fire all nozzles consistently after non-firing periods of 5, 10, 15, or up to 20 seconds.
There is a need to improve the printability of ink-jet inks that utilize latex polymers, whether of the foregoing formulations or of other formulations.
DISCLOSURE OF INVENTION
In accordance with the present invention, a solvent system has been found which aids in start-up, drop ejection, decap and high frequency firing above 10 kHz for inks which contain latex polymers. Two solvents work in conjunction with each other: 3-hexyne-2,5-diol and 1,2-octanediol. These two solvents in combination improve printability in latex polymer-containing ink-jet inks.
BEST MODES FOR CARRYING OUT THE INVENTION
Latex polymers, also termed “core/shell” polymers, are polymers having both hydrophilic and hydrophobic portions. Such polymers are primarily used in pigment-based inks to improve the smearfastness of the inks.
In accordance with the present invention, the printability of inks containing one or more latex polymers is improved by including in the vehicle of the ink the following two co-solvents: 3-hexyne-2,5-diol and 1,2-octanediol. These two solvents in combination improve the printability of latex polymer-containing ink-jet inks.
The first compound (3-hexyne-2,5-diol) is present in a range of about 1 to 8 wt %, while the second compound (1,2-octanediol) is present in a range of about 0.01 to 0.5 wt %, both of the total ink composition. Preferably, the second compound is employed at the lower range of concentration, due to its tendency to feather at higher concentrations.
Although the concentration of each compound may be independent of the other, it is preferred that the ratio of the first compound to the second compound be about 100:1 to 1:100, and preferably about 20:1.
The inks of the invention comprise a colorant and a vehicle. Specifically, the inks of the present invention comprise about 5 to 50 wt %, preferably about 10 to 25 wt %, water-miscible organic co-solvent, about 0.05 to 10 wt %, preferably about 0.5 to 10 wt %, colorant, about 0.005 to 50 wt %, preferably about 0.1 to 10 wt %, more preferably about 0.5 to 5 wt %, durable core/shell polymer, about 0.005 to 50 wt %, preferably about 0.1 to 10 wt %, more preferably about 0.5 to 5 wt %, primer core/shell polymer, and water. Other components and additives to the ink may also be present, as discussed below.
The black inks of the invention comprise a pigment and a vehicle. Specifically, 15 the black inks of the present invention comprise about 5 to 50 wt %, preferably about 10 to 25 wt %, water-miscible organic co-solvent, about 0.05 to 10 wt %, preferably about 0.5 to 10 wt %, pigment, about 0.005 to 50 wt %, preferably about 0.1 to 10 wt %, more preferably about 0.5 to 5 wt %, durable latex polymer, about 0.005 to 50 wt %, preferably about 0.1 to 10 wt %, more preferably about 0.5 to 5 wt %, primer latex polymer, and water, in addition to the ester or diol/triol additive discussed above. Other components and additives to the ink may also be present, as discussed below.
1. Self-Dispersed Pigments
In one embodiment, the colorant employed in the ink is a self-dispersing pigment. Such pigments suitable for use in the practice of the present invention i
Egwim Kelechi C.
Hewlett--Packard Company
Wu David W.
LandOfFree
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