U.S. patent application number 11/038946 was filed with the patent office on 2005-09-29 for inkjet inks containing crosslinked polyurethanes.
Invention is credited to Berge, Charles T., Li, Xiaoqing.
Application Number | 20050215663 11/038946 |
Document ID | / |
Family ID | 34807142 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050215663 |
Kind Code |
A1 |
Berge, Charles T. ; et
al. |
September 29, 2005 |
Inkjet inks containing crosslinked polyurethanes
Abstract
Inkjet inks are described that have, as a principal component, a
crosslinked polyurethane dispersoid binder additive. These inks can
be used for printing on different media, and are particularly
suitable for printing on paper.
Inventors: |
Berge, Charles T.;
(Greenville, DE) ; Li, Xiaoqing; (Newark,
DE) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
34807142 |
Appl. No.: |
11/038946 |
Filed: |
January 18, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60537880 |
Jan 21, 2004 |
|
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Current U.S.
Class: |
523/160 ;
523/161 |
Current CPC
Class: |
B41M 5/0023 20130101;
B41J 2/21 20130101; C09D 11/322 20130101; C09D 11/40 20130101; C09D
11/326 20130101; D06P 5/30 20130101; C09D 11/30 20130101; B41J 2/01
20130101; B41M 5/0088 20130101; Y10T 428/24802 20150115; B41M
5/0047 20130101 |
Class at
Publication: |
523/160 ;
523/161 |
International
Class: |
C09D 011/00; C03C
017/00 |
Claims
1. An inkjet ink composition comprising an aqueous vehicle having
stably dispersed therein a pigment and a crosslinked polyurethane
dispersoid, wherein the ink comprises the crosslinked polyurethane
dispersoid is an amount of more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the ink, and
wherein the amount of crosslinking in the crosslinked polyurethane
is greater than about 1% and less than about 50% (THF insolubles
test).
2. The inkjet ink composition of claim 1, wherein the crosslinking
in the crosslinked polyurethane is greater than about 4% and less
than about 50%.
3. The inkjet ink composition of claim 1, having a surface tension
in the range of about 20 dyne/cm to about 70 dyne/cm, and a
viscosity is in the range of about 1 cP to about 30 cP at
25.degree. C.
4. The inkjet ink composition of claim 1, wherein the crosslinked
polyurethane has incorporated therein hydrophilic functionality to
the extent required to maintain a stable dispersion of the polymer
in the aqueous vehicle.
5. The inkjet ink composition of claim 4, wherein the hydrophilic
functionality of the crosslinked polyurethane is derived from
anionic substituents.
6. An inkjet ink set comprising at least three differently colored
inkjet inks, wherein at least one of the inks is an inkjet ink
composition comprising an aqueous vehicle having stably dispersed
therein a pigment colorant and a crosslinked polyurethane
dispersoid, wherein the ink comprises the crosslinked polyurethane
dispersoid is an amount of more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the ink, and
wherein the amount of crosslinking in the crosslinked polyurethane
is greater than about 1% and less than about 50% (THF insolubles
test).
7. The inkjet ink set of claim 6, wherein ink set comprises: (a) a
first colored ink comprising a first aqueous vehicle having stably
dispersed therein a first pigment colorant and a first crosslinked
polyurethane dispersoid, wherein the first crosslinked polyurethane
dispersoid is more than about 0.5% to about 30% by weight (solids
basis), based on the total weight of the first ink, and wherein the
amount of crosslinking in the first crosslinked polyurethane
dispersoid is greater than about 1% and less than about 50%; (b) a
second colored ink comprising a second aqueous vehicle having
stably dispersed therein a second pigment colorant and a second
crosslinked polyurethane dispersoid, wherein the second crosslinked
polyurethane dispersoid is more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the second ink,
and wherein the amount of crosslinking in the second crosslinked
polyurethane dispersoid is greater than about 1% and less than
about 50%; and (c) a third colored ink comprising a third aqueous
vehicle having stably dispersed therein a third pigment colorant
and a third crosslinked polyurethane dispersoid, wherein the third
crosslinked polyurethane dispersoid is more than about 0.5% to
about 30% by weight (solids basis), based on the total weight of
the third ink, and wherein the amount of crosslinking in the third
crosslinked polyurethane dispersoid is greater than about 1% and
less than about 50%.
8. The inkjet ink set of claim 7, wherein the first colored ink is
a cyan ink, the second colored ink is a magenta ink and the third
colored ink is a yellow ink.
9. The inkjet ink set of claim 7, further comprising (d) a fourth
colored ink comprising a fourth aqueous vehicle having stably
dispersed therein a fourth pigment colorant and a fourth
crosslinked polyurethane dispersoid, wherein the fourth crosslinked
polyurethane dispersoid is more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the fourth ink,
and wherein the amount of crosslinking in the fourth crosslinked
polyurethane dispersoid is greater than about 1% and less than
about 50%.
10. The inkjet ink set of claim 9, wherein the first colored ink is
a cyan ink, the second colored ink is a magenta ink, the third
colored ink is a yellow ink and the fourth colored ink is a black
ink.
11. A method for inkjet printing onto a substrate, comprising the
steps of: (a) providing an inkjet printer that is responsive to
digital data signals; (b) loading the printer with a substrate to
be printed; (c) loading the printer with an inkjet ink composition
inkjet ink composition comprising an aqueous vehicle having stably
dispersed therein a pigment and a crosslinked polyurethane
dispersoid, wherein the ink comprises the crosslinked polyurethane
dispersoid is an amount of more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the ink, and
wherein the amount of crosslinking in the crosslinked polyurethane
is greater than about 1% and less than about 50% (THF insolubles
test); and (d) printing onto the substrate using the ink in
response to the digital data signals.
12. The method of claim 11, wherein the printer is loaded with an
inkjet ink set comprising at least three differently colored inkjet
inks, wherein at least one of the inks is an inkjet ink composition
comprising an aqueous vehicle having stably dispersed therein a
pigment colorant and a crosslinked polyurethane dispersoid, wherein
the ink comprises the crosslinked polyurethane dispersoid is an
amount of more than about 0.5% to about 30% by weight (solids
basis), based on the total weight of the ink, and wherein the
amount of crosslinking in the crosslinked polyurethane is greater
than about 1% and less than about 50% (THF insolubles test).
13. The method of claim 12, wherein ink set comprises: (a) a first
colored ink comprising a first aqueous vehicle having stably
dispersed therein a first pigment colorant and a first crosslinked
polyurethane dispersoid, wherein the first crosslinked polyurethane
dispersoid is more than about 0.5% to about 30% by weight (solids
basis), based on the total weight of the first ink, and wherein the
amount of crosslinking in the first crosslinked polyurethane
dispersoid is greater than about 1% and less than about 50%; (b) a
second colored ink comprising a second aqueous vehicle having
stably dispersed therein a second pigment colorant and a second
crosslinked polyurethane dispersoid, wherein the second crosslinked
polyurethane dispersoid is more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the second ink,
and wherein the amount of crosslinking in the second crosslinked
polyurethane dispersoid is greater than about 1% and less than
about 50%; and (c) a third colored ink comprising a third aqueous
vehicle having stably dispersed therein a third pigment colorant
and a third crosslinked polyurethane dispersoid, wherein the third
crosslinked polyurethane dispersoid is more than about 0.5% to
about 30% by weight (solids basis), based on the total weight of
the third ink, and wherein the amount of crosslinking in the third
crosslinked polyurethane dispersoid is greater than about 1% and
less than about 50%.
14. The method of claim 13, wherein the first colored ink is a cyan
ink, the second colored ink is a magenta ink and the third colored
ink is a yellow ink.
15. The method of claim 13, further comprising (d) a fourth colored
ink comprising a fourth aqueous vehicle having stably dispersed
therein a fourth pigment colorant and a fourth crosslinked
polyurethane dispersoid, wherein the fourth crosslinked
polyurethane dispersoid is more than about 0.5% to about 30% by
weight (solids basis), based on the total weight of the fourth ink,
and wherein the amount of crosslinking in the fourth crosslinked
polyurethane dispersoid is greater than about 1% and less than
about 50%.
16. The method of claim 15, wherein the first colored ink is a cyan
ink, the second colored ink is a magenta ink, the third colored ink
is a yellow ink and the fourth colored ink is a black ink.
17. The method of claim 11, wherein the substrate is a paper.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
from U.S. Provisional Application Ser. No. 60/537,880 (filed Jan.
21, 2004), the disclosure of which is incorporated by reference
herein for all purposes as if fully set forth.
[0002] This application is related to commonly owned U.S.
Application Ser. No. __/__,__, concurrently filed herewith,
entitled "Inkjet Inks Containing Crosslinked Polyurethanes", which
also claims priority under 35 U.S.C. .sctn.119 from U.S.
Provisional Application Ser. No. 60/537,880 (filed Jan. 21,
2004).
BACKGROUND OF THE INVENTION
[0003] This invention pertains to inkjet inks, more specifically to
pigmented inkjet inks containing crosslinked polyurethane
dispersoid binders, which are particularly suitable for printing on
paper and other media substrates.
[0004] Inkjet recording is a printing method wherein droplets of
ink are ejected through fine nozzles to form letters or figures on
the surface of recording media. Inks used in such recording are
subject to rigorous demands including, for example, good dispersion
stability, ejection stability, and good fixation to media.
[0005] Both dyes and pigments have been used as colorants for
inkjet inks. While dyes typically offer superior color properties
compared to pigments, they tend to fade quickly and are more prone
to rub off. Inks comprising pigments dispersed in aqueous media are
advantageously superior to inks using water-soluble dyes in
water-fastness and light-fastness of printed images. Additives to
the ink formulation are often required to achieve
water-fastness.
[0006] Pigments suitable for aqueous inkjet inks are in general
well known in the art. Traditionally, pigments are stabilized by
dispersing agents, such as polymeric dispersants or surfactants, to
produce a stable dispersion of the pigment in the vehicle. Other
additives to the ink modify the ink to match the needs for the
target printed system, which includes the media.
[0007] U.S. Pat. No. 6,034,154 discloses polymer fine particles,
each polymer fine particle containing a colorant. One of the
candidate polymers making up the polymer portion of the fine
particle is described as a crosslinked polyurethane.
[0008] U.S. Pat. No. 6,136,890 describes pigmented inks that
contain pigments and polyurethane dispersants that stabilize the
pigments. The pigment is dispersed by the polyurethane via
dispersing techniques used to achieve a stabile pigment
dispersion.
[0009] U.S. Pat. No. 6,713,531 describes a water-based pigmented
ink for use in inkjet printing (on paper and transparency media).
The ink consists of a pigment and a latex, of which uncrosslinked
polyurethanes are listed as candidate latexes.
[0010] WO03/029318 describes polyurethane block copolymers as
dispersants for inks. These polyurethanes are crosslinked prior to
inversion (addition of water to produce the polyurethane
dispersion) not during or after inversion. There is also
crosslinking derived from the added melamine crosslinker that is
only effective at high temperatures and/or acidic conditions that
occur at the time of the textile treatments after printing.
[0011] U.S. Pat. No. 6,063,834 describes an ink composition that
can contain a polyurethane having chemical components that would
make it hydrophobic and likely not dispersible in water.
[0012] The disclosures of all of the above-identified publications
are incorporated by reference for all purposes as if fully set
forth.
[0013] A disadvantage of inkjet printing, in particular inkjet
printing with pigmented ink, is inkjet printed paper can lack
durability that is required for the printed paper. Waterfastness is
of the printed image still needs improvement.
[0014] Still, there is need in the art for improved durability of
inkjet images, especially on paper, and especially in cases where
the colorant is pigment.
SUMMARY OF THE INVENTION
[0015] It was found that the water-fastness of an inkjet printed
paper (as well as other substrates) can be improved by using a
crosslinked polyurethane dispersoid binder in aqueous inkjet
inks.
[0016] Thus, in one aspect of the present invention, there is
provided an inkjet ink composition comprising an aqueous vehicle
having stably dispersed therein a pigment and a crosslinked
polyurethane dispersoid, wherein the ink comprises the crosslinked
polyurethane dispersoid is an amount of more than about 0.5% to
about 30% by weight (solids basis), based on the total weight of
the ink, and wherein the amount of crosslinking in the crosslinked
polyurethane is greater than about 1% and less than about 50% (THF
insolubles test). The inkjet ink may optionally comprise other
well-known additives or adjuvants as required to obtain final
desired properties.
[0017] The colorant in the inkjet ink preferably ranges from about
0.1 to about 30 wt %, based on the total weight of the ink, and is
a pigment.
[0018] In accordance with another aspect of the present invention,
there is provided an inkjet ink set comprising at least three
differently colored inkjet inks, wherein at least one of the inks
is an inkjet ink as set forth above.
[0019] In yet another aspect of the present invention, there is
provided a method for inkjet printing onto a substrate, comprising
the steps of:
[0020] (a) providing an inkjet printer that is responsive to
digital data signals;
[0021] (b) loading the printer with a substrate to be printed;
[0022] (c) loading the printer with an ink as set forth above and
described in further detail below, or an inkjet ink set as set
forth above and described in further detail below; and
[0023] (d) printing onto the substrate using the ink or inkjet ink
set in response to the digital data signals.
[0024] As indicated above, the inks and ink sets in accordance with
the present invention are particularly useful as inkjet inks, more
particularly as inkjet inks for printing on paper, transparencies,
polymeric media and optionally textiles. Preferred substrates,
therefore, include paper.
[0025] These and other features and advantages of the present
invention will be more readily understood by those of ordinary
skill in the art from a reading of the following detailed
description. It is to be appreciated that certain features of the
invention which are, for clarity, described above and below in the
context of separate embodiments, may also be provided in
combination in a single embodiment. Conversely, various features of
the invention that are, for brevity, described in the context of a
single embodiment, may also be provided separately or in any
subcombination. In addition, references in the singular may also
include the plural (for example, "a" and "an" may refer to one, or
one or more) unless the context specifically states otherwise.
Further, reference to values stated in ranges include each and
every value within that range.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The aqueous inks comprise an aqueous vehicle, a colorant, a
crosslinked polyurethane dispersoid binder and other optional ink
components, wherein the colorant is soluble or dispersible in the
aqueous vehicle.
[0027] In accordance with the present invention, the term
"polyurethane dispersoid" refers to an aqueous dispersion/emulsion
of a polymer containing urethane groups (e.g., polyurethane), as
those terms are understood by persons of ordinary skill in the art.
The aqueous crosslinked polyurethane dispersoid in accordance with
the present invention comprises a crosslinked polyurethane, and
thus is an aqueous stable polyurethane emulsion or dispersion in
which the polyurethane contains some crosslinking. To distinguish
the polyurethane dispersions/emulsion binders from the other
dispersions and components in the inkjet ink, they are referred to
herein as polyurethane "dispersoid(s)".
[0028] The crosslinked polyurethane dispersoid is combined with the
aqueous vehicle and colorant to produce a stable inkjet ink that
can be used to print paper. The crosslinked polyurethane preferably
has had substantially all of its crosslinking completed prior to
its addition to the other inkjet ink components. The order of
addition of the ink components can be in any convenient order.
[0029] Examples of polyurethanes that can be used in the
crosslinked polyurethane dispersoids are described below. As
indicated above, the crosslinking of the polyurethanes is
preferably achieved prior to its addition to the ink system.
[0030] Pigment Colorants
[0031] Pigments suitable for used in the present invention are
those generally well-known in the art for aqueous inkjet inks.
Traditionally, pigments are stabilized by dispersing agents, such
as polymeric dispersants or surfactants, to produce a stable
dispersion of the pigment in the vehicle. More recently though,
so-called "self-dispersible" or "self-dispersing" pigments
(hereafter "SDP") have been developed. As the name would imply,
SDPs are dispersible in water without dispersants. Dispersed dyes
are also considered pigments as they are insoluble in the aqueous
inks used herein.
[0032] Pigments that are stabilized by added dispersing agents may
be prepared by methods known in the art. It is generally desirable
to make the stabilized pigment in a concentrated form. The
stabilized pigment is first prepared by premixing the selected
pigment(s) and polymeric dispersant(s) in an aqueous carrier medium
(such as water and, optionally, a water-miscible solvent), and then
dispersing or deflocculating the pigment. The dispersing step may
be accomplished in a 2-roll mill, media mill, a horizontal mini
mill, a ball mill, an attritor, or by passing the mixture through a
plurality of nozzles within a liquid jet interaction chamber at a
liquid pressure of at least 5,000 psi to produce a uniform
dispersion of the pigment particles in the aqueous carrier medium
(microfluidizer). Alternatively, the concentrates may be prepared
by dry milling the polymeric dispersant and the pigment under
pressure. The media for the media mill is chosen from commonly
available media, including zirconia, YTZ, and nylon. These various
dispersion processes are in a general sense well known in the art,
as exemplified by U.S. Pat. Nos. 5,022,592, 5,026,427, 5,310,778,
5,891,231, 5,679,138, 5,976,232 and US20030089277. The disclosure
of each of these publications is incorporated by reference herein
for all purposes as if fully set forth. Preferred are 2-roll mill,
media mill, and by passing the mixture through a plurality of
nozzles within a liquid jet interaction chamber at a liquid
pressure of at least 5,000 psi.
[0033] After the milling process is complete the pigment
concentrate may be "let down" into an aqueous system. "Let down"
refers to the dilution of the concentrate with mixing or
dispersing, the intensity of the mixing/dispersing normally being
determined by trial and error using routine methodology, and often
being dependent on the combination of the polymeric dispersant,
solvent and pigment.
[0034] The dispersant used to stabilize the pigment is preferably a
polymeric dispersant. Either structured or random polymers may be
used, although structured polymers are preferred for use as
dispersants for reasons well known in the art. The term "structured
polymer" means polymers having a block, branched or graft
structure. Examples of structured polymers include AB or BAB block
copolymers such as disclosed in U.S. Pat. No. 5,085,698; ABC block
copolymers such as disclosed in EP-A-0556649; and graft polymers
such as disclosed in U.S. Pat. No. 5,231,131. Other polymeric
dispersants that can be used are described, for example, in U.S.
Pat. Nos. 6,117,921, 6,262,152, 6,306,994 and 6,433,117. The
disclosure of each of these publications is incorporated herein by
reference for all purposes as if fully set forth.
[0035] Polymer dispersants suitable for use in the present
invention generally comprise both hydrophobic and hydrophilic
monomers. Some examples of hydrophobic monomers used in random
polymers are methyl methacrylate, n-butyl methacrylate,
2-ethylhexyl methacrylate, benzyl methacrylate, 2-phenylethyl
methacrylate and the corresponding acrylates. Examples of
hydrophilic monomers are methacrylic acid, acrylic acid,
dimethylaminoethyl(meth)acrylate and salts thereof. Also quaternary
salts of dimethylaminoethyl(meth)acrylate may be employed.
[0036] A wide variety of organic and inorganic pigments, alone or
in combination, may be selected to make the ink. The term "pigment"
as used herein means an insoluble colorant. The pigment particles
are sufficiently small to permit free flow of the ink through the
inkjet printing device, especially at the ejecting nozzles that
usually have a diameter ranging from about 10 micron to about 50
micron. The particle size also has an influence on the pigment
dispersion stability, which is critical throughout the life of the
ink. Brownian motion of minute particles will help prevent the
particles from flocculation. It is also desirable to use small
particles for maximum color strength and gloss. The range of useful
particle size is typically about 0.005 micron to about 15 micron.
Preferably, the pigment particle size should range from about 0.005
to about 5 micron and, most preferably, from about 0.005 to about 1
micron. The average particle size as measured by dynamic light
scattering is preferably less than about 500 nm, more preferably
less than about 300 nm.
[0037] The selected pigment(s) may be used in dry or wet form. For
example, pigments are usually manufactured in aqueous media and the
resulting pigment is obtained as water-wet presscake. In presscake
form, the pigment is not agglomerated to the extent that it is in
dry form. Thus, pigments in water-wet presscake form do not require
as much deflocculation in the process of preparing the inks as
pigments in dry form. Representative commercial dry pigments are
listed in previously incorporated U.S. Pat. No. 5,085,698.
[0038] In the case of organic pigments, the ink may contain up to
about 30%, preferably about 0.1 to about 25%, and more preferably
about 0.25 to about 10%, pigment by weight based on the total ink
weight. If an inorganic pigment is selected, the ink will tend to
contain higher weight percentages of pigment than with comparable
inks employing organic pigment, and may be as high as about 75% in
some cases, since inorganic pigments generally have higher specific
gravities than organic pigments.
[0039] Self-dispersed pigments (SDPs) can be use with the
crosslinked polyurethane dispersoids and are often advantageous
over traditional dispersant-stabilized pigments from the standpoint
of greater stability and lower viscosity at the same pigment
loading. This can provide greater formulation latitude in final
ink.
[0040] SDPs, and particularly self-dispersing carbon black
pigments, are disclosed in, for example, U.S. Pat. Nos. 2,439,442,
3,023,118, 3,279,935 and 3,347,632. Additional disclosures of SDPs,
methods of making SDPs and/or aqueous inkjet inks formulated with
SDP's can be found in, for example, U.S. Pat. Nos. 5,554,739,
5,571,311, 5,609,671, 5,672,198, 5,698,016, 5,707,432, 5,718,746,
5,747,562, 5,749,950, 5,803,959, 5,837,045, 5,846,307, 5,851,280,
5,861,447, 5,885,335, 5,895,522, 5,922,118, 5,928,419, 5,976,233,
6,057,384, 6,099,632, 6,123,759, 6,153,001, 6,221,141, 6,221,142,
6,221,143, 6,281,267, 6,329,446, U.S. Pat. No. 2001/0035110,
EP-A-1114851, EP-A-1158030, WO01/10963, WO01/25340 and WOO1/94476.
The disclosures of all of the above-identified publications are
incorporated by reference herein for all purposes as if fully set
forth.
[0041] Polyurethane Dispersoid Binders (PUDs)
[0042] As indicated above, a crosslinked polyurethane dispersoid
refers to an aqueous dispersion of a polymer containing urethane
groups and crosslinking, as those terms are understood by persons
of ordinary skill in the art. These polymers may also incorporate
hydrophilic functionality to the extent required to maintain a
stable dispersion of the polymer in water and, more preferably, the
aqueous vehicle. The main advantage of incorporating hydrophilic
functionality into the polymer is that dispersion can be performed
with minimal energy so that the dispersing processes do not require
strong shear forces, resulting in finer particle size, better
dispersion stability, and reduced water sensitivity of the polymers
obtained after evaporation of the water. These polymers may also
incorporate ionic and nonionic functionality to the extent required
to maintain a stable dispersion of the polymer in water.
Alternatively, these polymers can be prepared by emulsification of
hydrophobic polyurethanes in water with the aid of suitable
external emulsifiers, surfactants and the like, and/or utilizing
strong shear forces to form an oil-in-water dispersion.
[0043] In general, the stability of the crosslinked polyurethane in
the aqueous vehicle is achieved by incorporating anionic, cationic
and/or non-ionic components in the polyurethane polymer, which
facilitates stabilizing the crosslinked polyurethane in aqueous
systems. External emulsifiers may also be added to stabilize the
polyurethane. Combinations of incorporated anionic, cationic and/or
non-ionic components, and/or external emulsifiers can also be
used.
[0044] Examples of suitable polyurethanes are those in which the
polymer is predominantly stabilized in the dispersion through
incorporated anionic functionality, and an example of this is
anionic functionality such as neutralized acid groups ("anionically
stabilized polyurethane dispersoid"). Further details are provided
below. Further examples of hydrophilic functionalization are
cationic and nonionic functionality.
[0045] Suitable aqueous polyurethane dispersoids are typically
prepared by multi-step synthetic processes in which an NCO
terminated prepolymer is formed, this prepolymer is added to water
or water is added to the prepolymer forming a polymer dispersed in
water (aqueous dispersion) and subsequently chain extended in the
aqueous phase. The pre-polymer can be formed by a single or
multi-step process. Chain extension, if used, can also be a single
or multi-step process. The important crosslinking can occur as part
of these single or multi-step processes.
[0046] After the polyurethane dispersoid is prepared it is included
with the other ink components to produce the inkjet ink. The
details of the preparation of the ink are familiar to those skilled
in the art.
[0047] It is preferred that the crosslinking for the polyurethane
is substantially completed prior to its addition to the ink
formulation. Other uses of polyurethanes in inkjet system can
require that there is a component in the polyurethane which
undergoes crosslink at the time of the ink formulation, or more
likely at the time of the printing, or post treatment of the
printed material. Alternatively, a crosslinking species can be
added to affect the crosslinking at the ink formulation time or
later. Each of these processes can be described as a
post-crosslinking system,
[0048] As indicated above, the polyurethane dispersoid is typically
prepared by a multiple step process. Typically, in the first stage
of prepolymer formation, a diisocyanate is reacted with a compound,
polymer, or mixtures of compound, mixture of polymers or a mixture
thereof, each containing two NCO-reactive groups. An additional
compound or compounds, all containing .gtoreq.2 NCO-reactive groups
as well as a stabilizing ionic functionality, is also used to form
an intermediate polymer. This intermediate polymer or pre-polymer
can be terminated with either an NCO-group or a NCO-reactive group.
The terminal groups are defined by the molar ratio of NCO to
NCO-reactive groups in the prepolymer stage. Typically, the
pre-polymer is an NCO-terminated material that is achieved by using
a molar excess of NCO. Thus, the molar ratio of diisocyanate to
compounds containing two isocyanate-reactive groups is at least
about 1.1:1.0, preferably about 1.20:1.0 to about 5.0:1.0, and more
preferably about 1.20:1.0 to about 2.5:1.0. In general, the ratios
are achieved by preparing, in a first stage, an NCO-terminated
intermediate by reacting one of the NCO-reactive compounds, having
at least 2 NCO reactive groups, with all or part of the
diisocyanate. This is followed, in sequence, by additions of other
NCO-reactive compounds, if desired. When all reactions are complete
the group, NCO and/or NCO-reactive groups will be found at the
termini of the pre-polymer. These components are reacted in amounts
sufficient to provide a molar ratio such that the overall
equivalent ratio of NCO groups to NCO-reactive groups is
achieved.
[0049] Suitable diisocyanates are those that contain either
aromatic, cycloaliphatic or aliphatic groups bound to the
isocyanate groups. Mixtures of these compounds may also be used.
The preferred is a prepolymer that has isocyanates bound to a
cycloaliphatic or aliphatic moieties. If aromatic diisocyanates are
used, cycloaliphatic or aliphatic isocyanates are preferably
present as well.
[0050] Examples of suitable diisocyanates include cyclohexane-1,3-
and -1,4-diisocyanate; 1-isocyanato-3-
isocyanatomethyl-3,5,5-trimethyl-cyclo- hexane (isophorone
diisocyanate or IPDI); bis-(4-isocyanatocyclohexyl)-met- hane; 1,3-
and 1,4-bis-(isocyanatomethyl)-cyclohexane;
1-isocyanato-2-isocyanatomethyl cyclopentane;
2,4'-diisocyanato-dicyclohe- xyl methane;
bis-(4-isocyanato-3-methyl-cyclohexyl)-methane,
alpha,alpha,alpha',alpha'-tetramethyl-1,3- and/or -1,4-xylylene
diisocyanate; 1-isocyanato-1-methyl-4(3)-isocyanatomethyl
cyclohexane; and 2,4- and/or 2,6-hexahydrotoluylene
diisocyanate.
[0051] Additional diisocyanates may be linear or branched and
contain 4 to 12 carbon atoms, preferably 4 to 9 carbon which
include 1,4-tetramethylene diisocyanate; 1,6-hexamethylene
diisocyanate; 2,2,4-trimethyl-1,6-hexamethylene diisocyanate; and
1,12-dodecamethylene diisocyanate. 1,6-hexamethylene diisocyanate
and isophorone diisocyanate are examples of diisocyanates effective
for the crosslinked polyurethanes
[0052] Examples of non-ionic dispersing groups include, for
example, a non-ionic dispersing segment present within the
polyurethane which is solvent-soluble and that promotes dispersion
of the polyurethane within a chosen solvent. When the chosen
solvent comprises water, for example, a non-ionic dispersing
segment can be a hydrophilic dispersing segment such as an alkylene
oxide or polyoxyalkylene oxide segment, e.g.,
--((CH.sub.2).sub.nO).sub.m--, wherein n can preferably be from 2
to 4, and m can be from about 1 to 400, preferably from about 5 to
200.
[0053] Isocyanate-reactive compounds containing ionic groups, for
example anionic and cationic groups, can be chemically incorporated
into the polyurethane to provide hydrophilicity and enable the
polyurethane to be dispersed in an aqueous medium.
[0054] Examples of ionic dispersing groups include carboxylate
groups (--COOM), phosphate groups (--OPO.sub.3 M.sub.2),
phosphonate groups (--PO.sub.3 M.sub.2), sulfonate groups
(--SO.sub.3 M), quaternary ammonium groups (--NR.sub.3 Y, wherein Y
is a monovalent anion such as chlorine or hydroxyl), or any other
effective ionic group. M is a cation such as a monovalent metal ion
(e.g., Na.sup.+, K.sup.+, Li.sup.+, etc.), H.sup.+, NR.sub.4.sup.+,
and each R can be independently an alkyl, aralkyl, aryl, or
hydrogen. These ionic dispersing groups are typically located
pendant from the polyurethane backbone.
[0055] In the case of anionic group substitution, the groups can be
carboxylic acid groups, carboxylate groups, sulphonic acid groups,
sulphonate groups, phosphoric acid groups and phosphonate groups,
The acid salts are formed by neutralizing the corresponding acid
groups either prior to, during or after formation of the NCO
prepolymer, preferably after formation of the NCO prepolymer.
[0056] Suitable compounds for incorporating carboxyl groups are
described in U.S. Pat. Nos. 3,479,310, 4,108,814 and 4,408,008, the
disclosures of which are incorporated by reference herein for all
purposes as if fully set forth. The neutralizing agents for
converting the carboxylic acid groups to carboxylate salt groups
are described in the preceding incorporated publications, and are
also discussed hereinafter. Within the context of this invention,
the term "neutralizing agents" is meant to embrace all types of
agents that are useful for converting carboxylic acid groups to the
more hydrophilic carboxylate salt groups. In like manner, sulphonic
acid groups, sulphonate groups, phosphoric acid groups, and
phosphonate groups can be neutralized with similar compounds to
their more hydrophilic salt form.
[0057] Examples of carboxylic group-containing compounds are the
hydroxy-carboxylic acids corresponding to the formula
(HO).sub.xQ(COOH).sub.y wherein Q represents a straight or
branched, hydrocarbon radical containing 1 to 12 carbon atoms, x is
1 or 2 (preferably 2), and y is 1 to 3 (preferably 1 or 2).
[0058] Examples of these hydroxy-carboxylic acids include citric
acid, tartaric acid and hydroxypivalic acid.
[0059] Especially preferred acids are those of the above-mentioned
formula wherein x=2 and y=1. These dihydroxy alkanoic acids are
described in U.S. Pat. No. 3,412,054, the disclosure of which is
incorporated by reference herein for all purposes as if fully set
forth. Especially preferred dihydroxy alkanoic acids are the
alpha,alpha-dimethylol alkanoic acids represented by the structural
formula: 1
[0060] wherein Q' is hydrogen or an alkyl group containing 1 to 8
carbon atoms. The most preferred compound is alpha,alpha-dimethylol
propionic acid, i.e., wherein Q' is methyl in the above
formula.
[0061] When the ionic stabilizing groups are acids, the acid groups
are incorporated in an amount sufficient to provide an acid group
content, known by those skilled in the art as acid number (mg KOH
per gram solid polymer), of at least about 5, preferably at least
about 10 milligrams KOH per 1.0 gram of polyurethane. The upper
limit for the acid number (AN) is about 50, preferably about
40.
[0062] Suitable polyols containing at least two NCO reactive
groups, which may be reacted to prepare the prepolymer, are those
having a molecular weight of about 60 to about 6000. Of these, the
polymeric polyols are best defined by the number average molecular
weight, and can range from about 200 to about 6000, preferably
about 800 to about 3000, and more preferably about 1000 to about
2500. The molecular weights are determined by hydroxyl group
analysis (OH number). Examples of these high molecular weight
compounds include polyester, polyether, polycarbonates,
polyacetals, poly(meth)acrylates, polyester amides, polythioethers
or mixed polymers such as a polyester-polycarbonate where both
ester and carbonate linkages are found in the same polymer. A
combination of these polymers can also be used. For examples, a
polyester polyol and a poly(meth)acrylate polyol may be used in the
same polyurethane synthesis.
[0063] Similar NCO reactive materials can be used as described for
hydroxy containing compounds and polymers, but which contain other
NCO reactive groups. Examples would be dithiols, diamines,
thioamines and even hydroxythiols and hydroxylamines. These can
either be compounds or polymers with the molecular weights or
number average molecular weights as described for the polyols.
[0064] Suitable polyester diols include reaction products of
polyhydric, preferably dihydric alcohols to which trihydric
alcohols may optionally be added, and polybasic (preferably
dibasic) carboxylic acids. Instead of these polycarboxylic acids,
the corresponding carboxylic acid anhydrides or polycarboxylic acid
esters of lower alcohols or mixtures thereof may be used for
preparing the polyesters.
[0065] The polycarboxylic acids may be aliphatic, cycloaliphatic,
aromatic and/or heterocyclic or mixtures thereof and they may be
substituted, for example, by halogen atoms, and/or unsaturated. The
following are mentioned as examples: succinic acid; adipic acid;
suberic acid; azelaic acid; sebacic acid; 1,12-dodecyldioic acid;
phthalic acid; isophthalic acid; trimellitic acid; phthalic acid
anhydride; tetrahydrophthalic acid anhydride; hexahydrophthalic
acid anhydride; tetrachlorophthalic acid anhydride; endomethylene
tetrahydrophthalic acid anhydride; glutaric acid anhydride; maleic
acid; maleic acid anhydride; fumaric acid; dimeric and trimeric
fatty acids such as oleic acid, which may be mixed with monomeric
fatty acids; dimethyl terephthalates and bis-glycol
terephthalate.
[0066] Suitable polyhydric alcohols include, e.g., ethylene glycol;
propylene glycol-(1,2) and -(1,3); butylene glycol-(1,4) and
-(1,3); hexanediol-(1,6); octanediol-(1,8); neopentyl glycol;
cyclohexanedimethanol (1,4-bis-hydroxymethyl-cyclohexane);
2-methyl-1,3-propanediol; 2,2,4-trimethyl-1, 3-pentanediol;
triethylene glycol; tetraethylene glycol; polyethylene glycol;
dipropylene glycol; polypropylene glycol; dibutylene glycol and
poly-butylene glycol, glycerine, trimethylol-propane, polyether
diols such as polyethylene glycol, polypropylene glycol,
polybutylene glycol or mixed monomer polyether glycols. The
polyesters may also contain a portion of carboxyl end groups.
Polyesters of lactones, for example, epsilon-caprolactone, or
hydroxycarboxylic acids, for example, omegahydroxycaproic acid, may
also be used.
[0067] Polycarbonates containing hydroxyl groups include those
known, per se, such as the products obtained from the reaction of
diols such as propanediol-(1,3), butanediol-(1,4) and/or
hexanediol-(1,6), diethylene glycol, triethylene glycol or
tetraethylene glycol, higher polyether diols with phosgene,
diarylcarbonates such as diphenylcarbonate, dialkylcarbonates such
as diethylcarbonate or with cyclic carbonates such as ethylene or
propylene carbonate. Also suitable are polyester carbonates
obtained from the above-mentioned polyesters or polylactones with
phosgene, diaryl carbonates, dialkyl carbonates or cyclic
carbonates.
[0068] Suitable polyether polyols are obtained in a known manner by
the reaction of starting compounds that contain reactive hydrogen
atoms with alkylene oxides such as ethylene oxide, propylene oxide,
butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin or
mixtures of these. It is preferred that the polyethers do not
contain more than about 10% by weight of ethylene oxide units. Most
preferably, polyethers obtained without the addition of ethylene
oxide are used. Suitable starting compounds containing reactive
hydrogen atoms include the polyhydric alcohols set forth for
preparing the polyester polyols and, in addition, water, methanol,
ethanol, 1,2,6-hexane triol, 1,2,4-butane triol, trimethylol
ethane, pentaerythritol, mannitol, sorbitol, methyl glycoside,
sucrose, phenol, isononyl phenol, resorcinol, hydroquinone, 1,1,1-
and 1,1,2-tris-(hydroxylphenyl)-ethane, dimethylolpropionic acid or
dimethylolbutanoic acid.
[0069] Polyethers that have been obtained by the reaction of
starting compounds containing amine compounds can also be used.
Examples of these polyethers as well as suitable polyhydroxy
polyacetals, polyhydroxy polyacrylates, polyhydroxy polyester
amides, polyhydroxy polyamides and polyhydroxy polythioethers, are
disclosed in U.S. Pat. No. 4,701,480 (the disclosure of which is
incorporated by reference herein for all purposes as if fully set
forth).
[0070] Poly(meth)acrylates containing hydroxyl groups include those
common in the art of addition polymerization such as cationic,
anionic and radical polymerization and the like. Examples are
alpha-omega diols. An example of these type of diols are those
which are prepared by a "living" or "control" or chain transfer
polymerization processes which enables the placement of one
hydroxyl group at or near the termini of the polymer. U.S. Pat.
Nos. 6,248,839 and 5,990,245 (the disclosures of which are
incorporated by reference herein for all purposes as if fully set
forth) have examples of protocol for making terminal diols. Other
di-NCO reactive poly(meth)acrylate terminal polymers can be used.
An example would be end groups other than hydroxyl such as amino or
thiol, and may also include mixed end groups with hydroxyl.
[0071] The high molecular weight polyols are generally present in
the polyurethanes in an amount of at least about 5%, preferably at
least about 10% by weight, based on the weight of the polyurethane.
The maximum amount of these polyols is generally about 85%, and
preferably about 75% by weight, based on the weight of the
polyurethane.
[0072] Other optional compounds for preparing the NCO prepolymer
include low molecular weight, at least difunctional NCO-reactive
compounds having an average molecular weight of up to about 400.
Examples include the dihydric and higher functionality alcohols,
which have previously been described for the preparation of the
polyester polyols and polyether polyols.
[0073] In addition to the above-mentioned components, which are
preferably difunctional in the isocyanate polyaddition reaction,
mono-functional and even small portions of trifunctional and higher
functional components generally known in polyurethane chemistry,
such as trimethylolpropane or 4-isocyanantomethyl-1,8-octamethylene
diisocyanate, may be used in cases in which branching of the NCO
prepolymer or polyurethane is desired. However, the NCO prepolymers
should be substantially linear and this may be achieved by
maintaining the average functionality of the prepolymer starting
components at or below 2:1.
[0074] Other optional compounds include NCO-reactive compounds
containing branched and/or terminal, hydrophilic and/or hydrophobic
units. These units include non-ionic hydrophilic materials such as
polyethylene oxides or copolymers with other oxide, and hydrophilic
polyoxazolines. The content of hydrophilic units (when present) may
be up to about 10%, preferably up to about 8% and most preferably
about 2 to about 6%, by weight, based on the weight of the
polyurethane. In addition, up to about 75% of the allowable,
chemically incorporated, hydrophilic units may be replaced by known
nonionic, external emulsifiers. Examples of these are the alkaryl
type polyoxyethylene, nonyl phenyl ether or polyoxyethylene octyl
phenyl ether; those of the alkyl ether type such as polyoxyethylene
lauryl ether or polyoxyethylene oleyl ether; those of the alkyl
ester type such as polyoxyethylene laurate, polyoxyethylene oleate
or polyoxyethylene stearate; and those of the polyoxyethylene
benzylated phenyl ether type.
[0075] The isocyanate-reactive compounds for incorporating branched
and/or terminal, hydrophilic and/or hydrophobic units may contain
either one or two isocyanate-reactive groups, preferably hydroxy
groups. Examples of these compounds are disclosed in U.S. Pat. Nos.
3,905,929, 3,920,598 and 4,190,566 (the disclosures of which are
incorporated by reference herein for all purposes as if fully set
forth). Preferred hydrophilic components are the monohydroxy
polyethers or monohydroxyl oxazolines. These hydrophilic components
may be produced as described in the preceding patents by
alkoxylating a monofunctional starter, such as methanol or n-
butanol, using ethylene oxide and optionally another alkylene
oxide, such as propylene oxide or in the case of oxazolines,
methyloxazoline.
[0076] Other optional compounds include isocyanate-reactive
compounds containing self-condensing moieties. The content of these
compounds are dependent upon the desired level of self-condensation
necessary to provide the desirable resin properties.
3-amino-1-triethoxysilyl-propane is an example of a compound that
will react with isocyanates through the amino group and yet
self-condense through the silyl group when inverted into water.
[0077] Other optional compounds include isocyanate-reactive
compounds containing non-condensable silanes and/or fluorocarbons
with isocyanate reactive groups, which can be used in place of or
in conjunction with the isocyanate-reactive compounds. U.S. Pat.
Nos. 5,760,123 and 6,046,295 (the disclosures of which are
incorporated by reference herein for all purposes as if fully set
forth) list examples of methods for use of these optional
silane/fluoro-containing compounds.
[0078] Process conditions for preparing the NCO containing
prepolymers have been discussed in the publications previously
noted. The finished NCO containing prepolymer should have a
isocyanate content of about 1 to about 20%, preferably about 1 to
about 10% by weight, based on the weight of prepolymer solids.
[0079] Mixtures of compounds and/or polymers having mixed NCO
reactive groups are also possible.
[0080] The polyurethanes are typical prepared by chain extending
these NCO containing prepolymers. Chain extenders are polyamine
chain extenders, which can optionally be partially or wholly
blocked as disclosed in U.S. Pat. Nos. 4,269,748 and 4,829,122 (the
disclosures of which are incorporated by reference herein for all
purposes as if fully set forth). These publications disclose the
preparation of aqueous polyurethane dispersoids by mixing
NCO-containing prepolymers with at least partially blocked, diamine
or hydrazine chain extenders in the absence of water and then
adding the mixture to water. Upon contact with water the blocking
agent is released and the resulting unblocked polyamine reacts with
the NCO containing prepolymer to form the polyurethane.
[0081] Suitable blocked amines and hydrazines include the reaction
products of polyamines with ketones and aldehydes to form ketimines
and aldimines, and the reaction of hydrazine with ketones and
aldehydes to form ketazines, aldazines, ketone hydrazones and
aldehyde hydrazones. The at least partially blocked polyamines
contain at most one primary or secondary amino group and at least
one blocked primary or secondary amino group which releases a free
primary or secondary amino group in the presence of water.
[0082] Suitable polyamines for preparing the at least partially
blocked polyamines have an average functionality, i.e., the number
of amine nitrogens per molecule, of 2 to 6, preferably 2 to 4 and
more preferably 2 to 3. The desired functionalities can be obtained
by using mixtures of polyamines containing primary or secondary
amino groups. The polyamines are generally aromatic, aliphatic or
alicyclic amines and contain between 1 to 30, preferably 2 to 15
and more preferably 2 to 10 carbon atoms. These polyamines may
contain additional substituents provided that they are not as
reactive with isocyanate groups as the primary or secondary amines.
These same polyamines can be partially or wholly blocked
polyamines.
[0083] A suitable method of chain extension is to add polyamine to
the NCO-prepolymer before, during or after the pre-polymer
inversion into water. Optionally, the chain extension can occur
after pre-polymer inversion. The polyamines include
1-amino-3-aminomethyl-3,5,5- trimethylcyclohexane (isophorone
diamine or IPDA), bis-(4-amino-cyclohexyl)-methane,
bis-(4-amino-3-methylcyclohexyl)-methan- e, 1,6- diaminohexane,
hydrazine, ethylene diamine, diethylene triamine, triethylene
tetramine, tetraethylene pentamine and pentaethylene hexamine.
[0084] In some cases, chain termination may be desirable. This
requires the addition, in most cases, of a mono-NCO reactive
material such as a mono-amine or mono-alcohol. The materials can be
added before, during or after inversion of the pre-polymer.
Poly-NCO reactive materials can be used where one of the
NCO-reactive groups reacts substantially faster than the others.
Examples would be ethanol amine and diethanol amine. The amine
group will react much faster with the NCO group than the
alcohol.
[0085] Suitable chain terminators would be amines or alcohols
having an average functionality per molecule of 1, i.e., the number
of primary or secondary amine nitrogens or alcohol oxygens would
average 1 per molecule. The desired functionalities can be obtained
by using primary or secondary amino groups. The amines or alcohols
are generally aromatic, aliphatic or alicyclic and contain between
1 to 30, preferably 2 to 15 and more preferably 2 to 10 carbon
atoms. These may contain additional substituents provided that they
are not as reactive with isocyanate groups as the amine or alcohol
groups.
[0086] Chain terminators and chain extenders can be used together,
either as mixtures or as sequential additions to the
NCO-prepolymer.
[0087] The amount of chain extender and/or chain terminator to be
used in accordance with the present invention is dependent upon the
number of isocyanate groups in the prepolymer. Preferably, the
ratio of isocyanate groups of the prepolymer to isocyanate-reactive
groups of the chain extender/terminator is between about 1.0:0.6
and about 1.0:1.1, more preferably between about 1.0:0.7 and about
1.0:1.1, on an equivalent basis. Any isocyanate groups that are not
chain extended/terminated with an amine or alcohol will react with
water, which functions as a chain extender.
[0088] Chain extension can take place prior to addition of water in
the process, but typically takes place by combining the NCO
containing prepolymer, chain extender, water and other optional
components under agitation.
[0089] In order to have a stable dispersion, a sufficient amount of
the ionic groups (if present) must be neutralized so that, when
combined with the optional hydrophilic ethylene oxide and other
alkenyl oxide units and optional external emulsifiers, the
resulting polyurethane will remain stably dispersed in the aqueous
medium. Generally, at least about 70%, preferably at least about
80%, of the acid groups are neutralized to the corresponding
carboxylate salt groups. Alternatively, cationic groups in the
polyurethane can be quaternary ammonium groups (--NR.sub.3Y,
wherein Y is a monovalent anion such as chlorine or hydroxyl).
[0090] Suitable neutralizing agents for converting the acid groups
to salt groups include tertiary amines, alkali metal cations and
ammonia. Examples of these neutralizing agents are disclosed in
previously incorporated U.S. Pat. No. 4,701,480, as well as U.S.
Pat. No. 4,501,852 (the disclosure of which is incorporated by
reference herein for all purposes as if fully set forth). Preferred
neutralizing agents are the trialkyl-substituted tertiary amines,
such as triethyl amine, tripropyl amine, dimethylcyclohexyl amine,
and dimethylethyl amine. Substituted amines are also useful
neutralizing groups such as diethyl ethanol amine or diethanol
methyl amine.
[0091] Neutralization may take place at any point in the process.
Typical procedures include at least some neutralization of the
prepolymer, which is then chain extended/terminated in water in the
presence of additional neutralizing agent.
[0092] The final product is a stable aqueous dispersoid of
polyurethane particles having a solids content of up to about 60%
by weight, preferably about 15 to about 60% by weight and most
preferably about 30 to about 40% by weight. However, it is always
possible to dilute the dispersions to any minimum solids content
desired.
[0093] The means to achieve the crosslinking of the polyurethane
generally relies on at least one component of the polyurethane
(starting material and/or intermediate) having 3 or more functional
reaction sites. Reaction of each of the 3 (or more) reaction sites
will produce a crosslinked polyurethane (3-dimensional matrix).
When only two reactive sites are available on each reactive
components, only linear (albeit possibly high molecular weight)
polyurethanes can be produced. Examples of crosslinking techniques
include but are not limited to the following:
[0094] the isocyanate-reactive moiety has at least 3 reactive
groups, for example polyfunctional amines or polyol;
[0095] the isocyanate has at least 3 isocyanate groups;
[0096] the prepolymer chain has at least 3 reactive sites that can
react via reactions other than the isocyanate reaction, for example
with amino trialkoxysilanes;
[0097] addition of a reactive component with at least 3 reactive
sites to the polyurethane prior to its use in the inkjet ink
preparations, for example tri-functional epoxy crosslinkers;
[0098] addition of a water-dispersible crosslinker with oxazoline
functionality;
[0099] synthesis of a polyurethane with carbonyl functionality,
followed by addition of a dihydrazide compound; and any combination
of the these crosslinking methods and other crosslinking means
known to those of ordinary skill in the relevant art.
[0100] Also, it is understood that these crosslinking components
may only be a (small) fraction of the total reactive functionality
added to the polyurethane. For example, when polyfunctional amines
are added, mono- and difunctional amines may also be present for
reaction with the isocyanates. The polyfunctional amine may be a
minor portion of the amines.
[0101] The crosslinking preferably occurs during the preparation of
the polyurethane. A preferred time for the crosslinking in the
polyurethane reaction sequence would be at or after the time of the
inversion step. That is, crosslinking preferably occurs during the
addition of water to the polyurethane preparation mixture or
shortly thereafter. The inversion is that point where sufficient
water is added such that the polyurethane is converted to its
stable dispersed aqueous form. Most preferred is that the
crosslinking occurs after the inversion. Furthermore, substantially
all of the crosslinking of the polyurethane is preferably complete
prior to its incorporation into the ink formulation.
[0102] Alternatively, the crosslinking can occur during the initial
formation of the urethane bonds when the isocyanates or
isocyanate-reactive groups have 3 or more groups capable of
reacting. If the crosslinking is done at this early stage, the
extent of crosslinking must not lead to gel formation. Too much
crosslinking at this stage will prevent the formation of a stable
polyurethane dispersion.
[0103] The amount of crosslinking of the polyurethane to achieve
the desired inkjet ink for printing can vary over a broad range.
While not being bound to theory, the amount of crosslinking is a
function of the polyurethane composition, the whole sequence of
reaction conditions utilized to form the polyurethane and other
factors known to those of ordinary skill in the art. The extent of
crosslinking, the inkjet ink formulation, the colorant, other inks
in the inkjet set, the substrate and the printing technique all
contribute to the final printed performance. Based on techniques
described herein, a person of ordinary skilled in the art is able
to determine, via routine experimentation, the crosslinking needed
for a particularly type of polyurethane to obtain an effective
inkjet ink for the desired substrate. As indicated above, these
inks may be used for plain paper, photo paper, transparencies,
vinyl, textiles and other printable substrates.
[0104] The amount of crosslinking can be measured by a standard
tetrahydrofuran insolubles test. For the purposes of definition
herein, the tetrahydrofuran (THF) insolubles of the polyurethane
dispersoid is measured by mixing 1 gram of the polyurethane
dispersoid with 30 grams of THF in a pre-weighed centrifuge tube.
After the solution is centrifuged for 2 hours at 17,000 rpm, the
top liquid layer is poured out and the non-dissolved gel in the
bottom is left. The centrifuge tube with the non-dissolved gel is
re-weighed after the tube is put in the oven and dried for 2 hours
at 110.degree. C.
% THF insolubles of polyurethane=(weight of tube and non-dissolved
gel-weight of tube)/(sample weight*polyurethane solid %)
[0105] The upper limit of crosslinking is related to the ability to
make a stable aqueous polyurethane dispersion. If a highly
crosslinked polyurethane has adequate ionic or nonionic
functionality such that it is a stable when inverted into water,
then its level of crosslinking will lead to an improved inkjet ink
for textiles. The emulsion/dispersion stability of the crosslinked
polyurethane can be improved by added dispersants or emulsifiers.
The upper limit of crosslinking as measured by the THF insolubles
test is about 50%.
[0106] The lower limit of crosslinking in the polyurethane
dispersoid is about 1% or greater, preferably about 4% or greater,
and more preferably about 10% or greater, as measured by the THF
insolubles test.
[0107] An alternative way to achieve an effective amount of
crosslinking in the polyurethane is to choose a polyurethane that
has crosslinkable sites, then crosslink those sites via
self-crosslinking and/or added crosslinking agents. Examples of
self-crosslinking functionality includes, for example, silyl
functionality (self-condensing) available from certain starting
materials as indicated above, as well as combinations of reactive
functionalities incorporated into the polyurethanes, such as
epoxy/hydroxyl, epoxy/acid and isocyanate/hydroxyl. Examples of
polyurethanes and complementary crosslinking agents include: (1) a
polyurethane with isocyanate reactive sites (such as hydroxyl
and/or amine groups) and an isocyanate crosslinking reactant, and
2) a polyurethane with unreacted isocyanate groups and an
isocyanate-reactive crosslinking reactant (containing, for example,
hydroxyl and/or amine groups). The complementary reactant can be
added to the polyurethane, such that crosslinking can be done prior
to its incorporation into an ink formulation. The crosslinking
should preferably be substantially completed prior to the
incorporation of the dispersoid into the ink formulation. This
crosslinked polyurethane preferably has greater than about 1% to
less than about 50% crosslinking as measured by the THF insolubles
test.
[0108] Combinations of two or more polyurethane crosslinked
dispersoid binders may also be utilized in the formulation of the
ink.
[0109] The crosslinked polyurethane dispersoid can be mixed with
other binders, including latexes, and the like. A non-limiting list
of these binders includes dispersed acrylics, neoprenes, dispersed
nylons, and non-crosslinked polyurethanes dispersions (as defined
herein by the THF insolubles test).
[0110] The term "latex" as used herein refers to a polymer particle
that is dispersed in the vehicle. A latex is sometimes referred to
as an "emulsion polymer". A latex is stabilized to dispersion by
stabilizers which can be part of the polymer itself (internal
stabilizers) or separate species (external stabilizers) such as
emulsifiers.
[0111] Commercially available latexes have a median particle size
in the range of about 0.02 to about 3 microns. For the present
invention, the median particle size should preferably be less than
about 1 micron, more preferably less than about 0.5 microns, and
most preferably in the range of about 0.03 to about 0.3
microns.
[0112] Polymer synthesis for these latexes can be performed under
emulsion polymerization conditions with standard free radical
initiators, chain transfer initiators and surfactants. Chain
transfer agents such as dodecyl mercaptan and sulfur are used to
control the molecular weight, branching, and gel content. Molecular
weight is typically in the range of about 100,000 to over about
1,000,000 Dalton. The percent conversion is also controlled to
limit the gel content.
[0113] Aqueous Vehicle
[0114] "Aqueous vehicle" refers to water or a mixture of water and
at least one water-soluble organic solvent (co-solvent). Selection
of a suitable mixture depends on requirements of the specific
application, such as desired surface tension and viscosity, the
selected colorant, drying time of the ink, and the type of
substrate onto which the ink will be printed. Representative
examples of water-soluble organic solvents that may be selected are
disclosed in previously incorporated U.S. Pat. No. 5,085,698.
[0115] The aqueous inks of the present invention are comprised
primarily of water. Thus, the instant inks comprise at least about
40%, preferably at least about 45%, and more preferably at least
about 50% by weight of water, based on the total weight of the
ink.
[0116] If a mixture of water and a water-soluble solvent is used,
the aqueous vehicle typically will contain about 40% to about 95%
by weight water with the balance (i.e., about 60% to about 5% by
weight) being the water-soluble solvent. Preferred compositions
contain about 65% to about 95% by weight water, based on the total
weight of the aqueous vehicle.
[0117] The amount of aqueous vehicle in the ink is typically in the
range of about 70% to about 99.8%, and preferably about 80% to
about 99.8%, by weight based on total weight of the ink.
[0118] The aqueous vehicle can be made to be fast penetrating
(rapid drying) by including surfactants or penetrating agents such
as glycol ethers and 1,2-alkanediols. Glycol ethers include
ethylene glycol monobutyl ether, diethylene glycol mono-n-propyl
ether, ethylene glycol mono-iso-propyl ether, diethylene glycol
mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene
glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether,
triethylene glycol mono-n-butyl ether, diethylene glycol
mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol
mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene
glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether,
dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-
propyl ether, and dipropylene glycol mono-isopropyl ether.
1,2-alkanediols are preferably 1,2-C.sub.4-6 alkanediols, most
preferably 1,2- hexanediol. Suitable surfactants include
ethoxylated acetylene diols (e.g. Surfynols.RTM. series from Air
Products), ethoxylated primary (e.g. Neodol.RTM.) series from
Shell) and secondary (e.g. Tergitol.RTM. series from Union Carbide)
alcohols, Pluronic.RTM. block copolymer surfactants,
sulfosuccinates (e.g. Aerosol.RTM. series from Cytec),
organosilicones (e.g. Silwet.RTM. series from Witco) and fluoro
surfactants (e.g. Zonyl.RTM. series from DuPont).
[0119] The amount of glycol ether(s) and 1,2-alkanediol(s) added
must be properly determined, but is typically in the range of from
about 1 to about 15% by weight and more typically about 2 to about
10% by weight, based on the total weight of the ink.
[0120] Surfactants may be used, typically in the amount of about
0.01 to about 5% and preferably about 0.1 to about 1%, based on the
total weight of the ink.
[0121] In addition, solvents that are not water miscible may be
added to the ink to facilitate the printing the ink which has a
polyurethane dispersoid binder in it. While not being bound by
theory, it is believed that this added non-aqueous solvent assists
in the coalescence of the polyurethane onto the printed substrate,
especially a fabric in the case of textile printing. Examples of
these water-immiscible solvents are propylene carbonate and
dipropylene glycol monomethyl ether.
[0122] Proportion of Main Ingredients
[0123] The pigment levels employed in the textile inks are those
levels which are typically needed to impart the desired color
density to the printed image. Typically, pigment is present at a
level of about 0.1% up to a level of about 30% by weight of the
total weight of ink. Alternatively, the pigment can be about 0.25
to about 25% of the total weight of the ink. Further, the pigment
can be about 0.25 to about 15% of the total weight of the ink.
[0124] The crosslinked polyurethane dispersoid level employed is
dictated by the range of ink properties that can be tolerated.
Generally, polyurethane levels will range up to about 30%, more
particularly from more than about 0.5% up to about 30%, preferably
more than about 0.5% up to about 25%, and more preferably more than
about 0.5% to about 20%, by weight (polyurethane solids basis) of
the total weight of ink.
[0125] Effective levels of polyurethane are typically those where
the weight ratio of polyurethane (solids) to colorant (pigment) is
at least about 0.1, and preferably at least about 0.15. This weight
ratio must be balanced against other ink properties, such as
viscosity, to maintain acceptable jetting performance. The right
balance of properties must be determined for each circumstance,
which can be done by the person of ordinary skill in the art using
routine experimentation.
[0126] Other Ingredients
[0127] The inkjet ink may contain other ingredients as are well
known in the art. For example, anionic, nonionic, cationic or
amphoteric surfactants may be used. In aqueous inks, the
surfactants are typically present in the amount of about 0.01 to
about 5%, and preferably about 0.2 to about 2%, based on the total
weight of the ink.
[0128] Co-solvents, such as those exemplified in U.S. Pat. No.
5,272,201 (incorporated by reference herein for all purposes as if
fully set forth) may be included to improve pluggage inhibition
properties of the ink composition.
[0129] Biocides may be used to inhibit growth of
microorganisms.
[0130] Sequestering agents such as EDTA may also be included to
eliminate deleterious effects of heavy metal impurities.
[0131] Ink Properties
[0132] Jet velocity, separation length of the droplets, drop size
and stream stability are greatly affected by the surface tension
and the viscosity of the ink. Inkjet inks suitable for use with
inkjet printing systems should have a surface tension in the range
of about 20 dyne/cm to about 70 dyne/cm, more preferably about 25
to about 40 dyne/cm at 25.degree. C. Viscosity is preferably in the
range of about 1 cP to about 30 cP, more preferably about 2 to
about 20 cP at 25.degree. C. The ink has physical properties
compatible with a wide range of ejecting conditions, i.e., driving
frequency of the pen and the shape and size of the nozzle.
[0133] The inks should have excellent storage stability for long
periods. Preferably, the instant inks can sustain elevated
temperature in a closed container for extended periods (e.g.
70.degree. C. for 7 days) without substantial increase in viscosity
or particle size.
[0134] Further, the ink should not corrode parts of the inkjet
printing device it comes in contact with, and it should be
essentially odorless and non-toxic.
[0135] Inks of the instant invention can achieve the beneficial
durable properties of wash-fastness.
[0136] Ink Sets
[0137] The ink sets in accordance with the present invention
preferably comprise at least three differently colored inks (such
as CMY), and preferably at least four differently colored inks
(such as CMYK), wherein at least one of the inks is an aqueous
inkjet ink comprising an aqueous vehicle, a colorant and a
crosslinked polyurethane dispersoid, wherein the colorant is
soluble or dispersible in the aqueous vehicle, and wherein the ink
comprises the crosslinked polyurethane dispersoid is an amount of
at least about 0.5% by weight (solids basis), based on the total
weight of the ink, as set forth above.
[0138] The other inks of the ink set are preferably also aqueous
inks, and may contain dyes, pigments or combinations thereof as the
colorant. Such other inks are, in a general sense, well known to
those of ordinary skill in the art.
[0139] In one preferred embodiment, the ink set comprises three
differently colored inks as follows:
[0140] (a) a first colored ink comprising a first aqueous vehicle
having stably dispersed therein a first pigment colorant and a
first crosslinked polyurethane dispersoid, wherein the first
crosslinked polyurethane dispersoid is more than about 0.5% to
about 30% by weight (solids basis), based on the total weight of
the first ink, and wherein the amount of crosslinking in the first
crosslinked polyurethane dispersoid is greater than about 1% and
less than about 50%;
[0141] (b) a second colored ink comprising a second aqueous vehicle
having stably dispersed therein a second pigment colorant and a
second crosslinked polyurethane dispersoid, wherein the second
crosslinked polyurethane dispersoid is more than about 0.5% to
about 30% by weight (solids basis), based on the total weight of
the second ink, and wherein the amount of crosslinking in the
second crosslinked polyurethane dispersoid is greater than about 1%
and less than about 50%; and
[0142] (c) a third colored ink comprising a third aqueous vehicle
having stably dispersed therein a third pigment colorant and a
third crosslinked polyurethane dispersoid, wherein the third
crosslinked polyurethane dispersoid is more than about 0.5% to
about 30% by weight (solids basis), based on the total weight of
the third ink, and wherein the amount of crosslinking in the third
crosslinked polyurethane dispersoid is greater than about 1% and
less than about 50%.
[0143] Preferably, the first colored ink is a cyan ink, the second
colored ink is a magenta ink and the third colored ink is a yellow
ink.
[0144] In another preferred embodiment, this ink set further
comprises (d) a fourth colored ink comprising a fourth aqueous
vehicle having stably dispersed therein a fourth pigment colorant
and a fourth crosslinked polyurethane dispersoid, wherein the
fourth crosslinked polyurethane dispersoid is more than about 0.5%
to about 30% by weight (solids basis), based on the total weight of
the fourth ink, and wherein the amount of crosslinking in the
fourth crosslinked polyurethane dispersoid is greater than about 1%
and less than about 50%. Preferably this fourth colored ink is a
black ink.
[0145] The ink set may further comprise one or more
"gamut-expanding" inks, including different colored inks such as an
orange ink, a green ink, a red ink and/or a blue ink, and
combinations of full strength and light strengths inks such as
light cyan and light magenta. These "gamut-expanding" inks are
particularly useful in textile printing for simulating the color
gamut of analog screen printing, such as disclosed in previously
incorporated US20030128246.
[0146] Method of Printing
[0147] The inks and ink sets of the present invention can be by
printing with any inkjet printer. The substrate can be any suitable
substrate including plain paper (such as standard
elecrophotographic papers), treated paper (such as coated papers
like photographic papers), textile, and non-porous substrates
including polymeric films such as polyvinyl choride and
polyester.
[0148] This invention now will be further illustrated, but not
limited, by the following examples.
EXAMPLES
[0149] Tests used to characterize the polyurethane dispersoids, the
inks and the printed textiles were those commonly used in the art.
Some specific procedures are listed
[0150] Printing and Testinq Techniques
[0151] The inkjet printer used in the following examples was an
Epson 980.
[0152] The water-fastness was tested by printing a test image that
included at least one of the inventive or comparison colors.
Immediately after printing the test image, the paper was placed on
a 45.degree. Angle Plate and 2 drops of deionized water was dropped
across the test image at specified time intervals. The
water-fastness test was done at 10 seconds, 1 minute and 5 minutes
after printing. If the image was removed by the water, or smeared,
the test was considered a failed test and rated Not Good (NG). If
the image was not affected by the water, it was rated OK.
[0153] The colorant dispersion, or other stable aqueous colorant,
was prepared by techniques known in the inkjet art. A black pigment
dispersion was used for the ink examples except where noted.
[0154] Ingredients and Abbreviations
[0155] APTES=aminopropyltriethoxysilane
[0156] APTMS=aminopropyltrimethoxy silane
[0157] BZMA=benzyl methacrylate
[0158] CHBMA=1,3-cyclohexane bis(methyl amine)
[0159] DBTL=dibutyltindilaurate
[0160] DMEA=dimethylethanolamine
[0161] DMIPA=dimethylisopropylamine
[0162] DMPA=dimethylol propionic acid
[0163] EDA=ethylene diamine
[0164] EDTA=ethylenediamine tetraacetic acid
[0165] ETEGMA=ethoxytriethylenglycolmethacrylate
[0166] HDI=1,6-hexamethylene diisocyanate
[0167] IPDA=isophoronediamine
[0168] IPDI=isophoronediisocyanate
[0169] MAA=methyl acrylic acid
[0170] NMP=n-Methyl pyrolidone
[0171] POEA=2-phenoxyethyl acrylate ester
[0172] TEA=triethylamine
[0173] TEOA=triethanolamine
[0174] TETA=triethylenetetramine
[0175] THF=tetrahydrofuran
[0176] Unless otherwise noted, the above chemicals were obtained
from Aldrich (Milwaukee, Wis.) or other similar suppliers of
laboratory chemicals.
[0177] BYK.RTM. 348--a silicone surfactant from Byk-Chemie
(Wallingford, Conn.)
[0178] Cythane.RTM. 3174--an aliphatic polyisocyanate resin from
Cytec (West Patterson, N.J.)
[0179] Desmodur N3400, a hexamethylene diisocyanate 40 wt % dimer
and 60 wt % trimer blend from Bayer (Pittsburgh, Pa.)
[0180] Desmophene C 200--a polyester carbonate diol from Bayer
(Pittsburgh, Pa.)
[0181] GP426--a 2000 molecular weight silicone based diol from
Genesee Silicones, (Flint, Mich.)
[0182] Liponic.TM. EG-1--ethoxylated glycerin humectant from Lipo
Chemicals Inc. (Patterson, N.J.)
[0183] Silwet.RTM. L77--an organosilicone surfactant from GE
Silicones (Wilton, Conn.)
[0184] Surfynol.RTM. 104E--a nonionic surfactant from Air Products
(Allentown, Pa.)
[0185] Surfynol.RTM. 485E--a nonionic surfactant from Air Products
(Allentown, Pa.)
[0186] Surfynol.RTM. 440--a nonionic surfactant from Air Products
(Allentown, Pa.)
[0187] Terathane.RTM. 1400--a polytetramethylene oxide polyol from
E.I. du Pont de Nemours and Company (Wilmington, Del.)
[0188] Extent of Polyurethane Reaction
[0189] The extent of polyurethane reaction was determined by
detecting NCO % by dibutylamine titration, a common method in
urethane chemistry.
[0190] In this method, a sample of the NCO containing prepolymer is
reacted with a known amount of dibutylamine solution and the
residual amine is back titrated with HCl.
[0191] Particle Size Measurements
[0192] The particle size for the polyurethane dispersions, pigments
and the inks were determined by dynamic light scattering using a
Microtrac.RTM. UPA 150 analyzer from Honeywell/Microtrac
(Montgomeryville, Pa.).
[0193] This technique is based on the relationship between the
velocity distribution of the particles and the particle size. Laser
generated light is scattered from each particle and is Doppler
shifted by the particle Brownian motion. The frequency difference
between the shifted light and the unshifted light is amplified,
digitalized and analyzed to recover the particle size
distribution.
[0194] The reported numbers below are the volume average particle
size.
[0195] Solid Content Measurement
[0196] Solid content for the solvent free polyurethane dispersoids
was measured with a moisture analyzer, model MA50 from Sartorius.
For polyurethane dispersoid containing high boiling solvent, such
as NMP, the solid content was then determined by the weight
differences before and after baking in 150.degree. C. oven for 180
minutes
[0197] THF Insolubles Measurement
[0198] THF insolubles content of the polyurethanes was measured by
first mixing 1 gram of the polyurethane dispersoid with 30 grams of
THF in a pre-weighed centrifuge tube. After the solution was
centrifuged for 2 hours at 17,000 rpm, the top liquid layer was
poured out and the non-dissolved gel in the bottom was left. The
centrifuge tube with the non-dissolved gel was re-weighed after the
tube was put in the oven and dried for 2 hours at 110.degree.
C.
% Micro-gel of polyurethane=((weight of tube and non-dissolved
gel)-(weight of tube))/(sample weight*polyurethane solid %).
[0199] Preparation of Inks
[0200] Inks used in the examples were made according to standard
procedures in the inkjet art. Ingredient amounts are in weight
percent of the final ink. Polyurethane dispersoid binders and
colorants are quoted on a solids basis.
[0201] As an example of ink preparation, the ink vehicle was
prepared and added with stirring to the polyurethane dispersoid
binders. After stirring until a good dispersion was obtained, the
mixture was then added to the pigment dispersion and stirred for
another 3 hours, or until a good ink dispersion was obtained.
[0202] Preparation of Black Pigment Dispersion
[0203] A black dispersion was prepared by first mixing well the
following ingredients: (i) 210.4 parts by weight (pbw) deionized
water, (ii) 80.3 pbw of a 41.5 wt % (solids) anionic polymeric
dispersant, and (iii) 9.24 pbw of dimethylethanolamine. The anionic
polymer dispersant was a graft co-polymer 66.3/-g-4.2/29.5
POEA/-g-ETEGMA/MAA prepared according to "Preparation of Dispersant
1" from previously incorporated US20030128246, with the ratios of
monomers adjusted to obtain the 66.2/4.2/29.5 instead of the
61.6/5.8/32.6 ratio indicated in the publication.
[0204] To this was gradually added 100 pbw black pigment (Nipex
180IQ, Degussa). After the pigment was incorporated, 100 pbw
deionized water was mixed in to form the millbase, which was
circulated through a media mill for grinding. 55.4 pbw deionized
water was then added for dilution to final strength.
[0205] The resulting 15 wt % dispersion had the following
properties: a viscosity of 8.60 cP (Brookfield viscometer,
20.degree. C.), a pH of about 7.5 and a median particle size of 92
nm.
[0206] Polyurethane Dispersoid 1 (PUD EX 1)
[0207] To a dry, alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 699.2 g Desmophene C 200, 280.0 g acetone and 0.06 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 189.14 g
IPDI was then added to the flask via the addition funnel at
40.degree. C. over 60 min, with any residual IPDI being rinsed from
the addition funnel into the flask with 15.5 g acetone.
[0208] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 44.57 g DMPA followed by 25.2 g TEA was then added
to the flask via the addition funnel, which was then rinsed with
15.5 g acetone. The flask temperature was then raised again to
50.degree. C. until NCO % was 1.14% or less.
[0209] With the temperature at 50.degree. C., 1498.0 g deionized
(DI) water was added over 10 minutes, followed by mixture of 97.5 g
EDA (as a 6.25% solution in water) and 29.7 g TETA (as a 6.25%
solution in water) over 5 minutes, via the addition funnel, which
was then rinsed with 80.0 g water. The mixture was held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0210] Acetone (-310.0 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 35.0% solids by weight.
[0211] For polyurethane dispersoid 1, the crosslinking was achieved
by the TETA.
[0212] Polyurethane Dispersoid 2 (PUD EX 2)
[0213] To a dry, alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 699.2 g Desmophene C 200, 280.0 g acetone and 0.06 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 189.14 g
IPDI was then added to the flask via the addition funnel at
40.degree. C. over 60 min, with any residual IPDI being rinsed from
the addition funnel into the flask with 15.5 g acetone.
[0214] The flask temperature was raised to 50.degree. C., then held
for 30 minutes. 44.57 g DMPA followed by 25.2 g TEA was added to
the flask via the addition funnel, which was then rinsed with 15.5
g acetone. The flask temperature was then raised again to
50.degree. C. and held at 50.degree. C. until NCO % was less than
1.23%.
[0215] With the temperature at 50.degree. C., 1498.0 g deionized
(DI) water was added over 10 minutes, followed by mixture of 24.4 g
EDA (as a 6.25% solution in water) and 118.7 g TETA (as a 6.25%
solution in water) over 5 minutes, via the addition funnel, which
was then rinsed with 80.0 g water. The mixture was held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0216] Acetone (-310.0 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 35.0% solids by weight.
[0217] For polyurethane dispersoid 2 the crosslinking was achieved
by the TETA.
[0218] Polyurethane DisDersoid 3 (PUD EX 3)
[0219] To a dry alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 375.0 g Desmophene C200, 156.7 g acetone and 0.04 g DBTL. The
contents were heated to 40.degree. C. and mixed well. 107.5 g IPDI
and 18.5 g Desmodur N3400 were then charged to the flask via the
addition funnel over 60 min, with any residual isocyanate being
rinsed from the addition funnel into the flask with 11.3 g
acetone.
[0220] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 31.5 g DMPA followed by 20.2 g TEA was then added
to the flask via the addition funnel, which was then rinsed with
7.4 g of acetone. The flask temperature was then held at 50.degree.
C. until the NCO % was less than 1.23%.
[0221] With temperature at 50.degree. C., 850.0 g DI water was
added over 10 minutes, followed by 100.0 g EDA (as a 6.25% solution
in water) over 5 minutes, via the addition funnel, which was then
rinsed with 50.0 g of water. The mixture was then held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0222] Acetone (-176.7 9) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 33% solids by weight.
[0223] For polyurethane dispersoid 3 the crosslinking was achieved
by the polyfunctional isocyanate component of the Desmodur
N3400.
[0224] Polyurethane Dispersoid 4 (PUD EX 4)
[0225] To a dry alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 363.3 g Desmophene C 200, 115.4 g acetone and 0.04 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 113.5 g
IPDI was then charged to the flask via the addition funnel over 60
min, with any residual IPDI being rinsed from the addition funnel
into the flask with 5.8 g acetone.
[0226] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 28.9 g DMPA followed by 19.6 g TEA was then added
to the flask via the addition funnel, which was then rinsed with
4.0 g of acetone. The flask temperature was held at 50.degree. C.
until NCO % was less than 1.50%. Then 32.4 g Cythane.RTM.) 3174
(Cytec) was charged and held at 50.degree. C. for 5 minutes,
followed by adding 600 g DI water over 10 minutes, and 120.0 g EDA
(as a 6.25% solution in water) over 5 minutes, via the addition
funnel, which was then rinsed with 40.0 g of water. The mixture was
then held at 50.degree. C. for 1 hr, then cooled to room
temperature.
[0227] Acetone (-125.2 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 37% solids by weight.
[0228] For polyurethane dispersoid 4 the crosslinking was achieved
by the polyfunctional isocyanate Cythane.RTM. 3174.
[0229] Polyurethane Dispersoid 5 (PUD EX 5)
[0230] To a dry, alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line was
added 327.64 g Terathane.RTM. 1400, 126.3 g acetone and 0.06 g
DBTL. The contents were heated to 40.degree. C. and mixed well.
115.36 g IPDI was then added to the flask via the addition funnel
at 40.degree. C. over 60 min, with any residual IPDI being rinsed
from the addition funnel into the flask with 7.5 g acetone.
[0231] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 22.2 g DMPA followed by 12.6 g TEA was added to the
flask via the addition funnel, which was then rinsed with 8.0 g
acetone. The flask temperature was then raised again to 50.degree.
C. held at 50.degree. C. until NCO % was less than 1.58%.
[0232] With the temperature at 50.degree. C., 860.0 g deionized
(DI) water was added over 10 minutes, followed 81.4 g TETA (as a
6.25% solution in water) over 5 minutes, via the addition funnel,
which was then rinsed with 80.0 g water. The mixture was held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0233] Acetone (-141.8 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 30.0% solids by weight.
[0234] For polyurethane dispersoid 4, the crosslinking was achieved
by the TETA.
[0235] Polyurethane Dispersoid 6 (PUD EX 6)
[0236] To a dry alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 219.95 g Desmophene C 200, 44.10 g acetone and 0.007 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 73.30 g
IPDI was then added to the flask via the addition funnel over 60
min, with any residual IPDI being rinsed from the addition funnel
into the flask with 10.90 g acetone.
[0237] The flask temperature was raised to 50.degree. C. and held
for 30-60 minutes (until the NCO %=5.0). 11.10 g DMPA followed by
8.88 g TEA was then added to the flask via the addition funnel,
which was then rinsed with 4.17 g of acetone. The flask temperature
was then held at 50.degree. C. for about 60 minutes (until the NCO
%=3.0), then cooled to 30.degree. C. 30.40 g APTES was added over
50-60 minutes while controlling the exotherm to not higher than
45.degree. C. The temperature was then raised to 50.degree. C.
until the NCO %=1.4%
[0238] With temperature at 50.degree. C., 544.31 g DI water was
added over 10 minutes, followed by 52.86 g of a 6.25% solution of
EDA in water over 5 minutes, via the addition funnel. The mixture
was then held at 50.degree. C. for 1 hr, then cooled to room
temperature.
[0239] Acetone (-59.17 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 36% solids by weight.
[0240] For polyurethane dispersoid 6, the crosslinking was achieved
by the APTES.
[0241] Properties for Polyurethane Dispersoids 1-6 and Comparative
Polyurethane Dispersoid 1
[0242] Polyurethane dispersoid physical properties and the THF
insolubles were measured and reported in Table 1.
1TABLE 1 Polyurethane Dispersoid Properties PUD PUD PUD EX 1 EX 2
EX 3 PUD EX 4 PUD EX 5 PUD EX 6 Viscosity (cps) 66 20 50 268 184 36
Solids % 35.2 35.9 32.8 36.9 30 36 pH 7.48 7.59 7.50 7.5 8.45 8.42
Particle Size 65 64 62.5 42 41 85 (nm) THF insolu- 5 18.3 17.8 2.6
84 14.8 bles, %
[0243] Polyurethane dispersoids 1-6 showed a range of THF
insolubles indicating a range of crosslinking. The comparative
example had no THF insolubles.
[0244] Polyurethane Dispersoid 7 (PUD EX 7)
[0245] To a dry, alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 340 g Desmophene C 200, 9.8 g GP426, 140 g acetone and 0.04 g
DBTL. The contents were heated to 40.degree. C. and mixed well.
94.2 g IPDI was then added to the flask via the addition funnel at
40.degree. C. over 60 min, with any residual IPDI being rinsed from
the addition funnel into the flask with 7.7 g acetone.
[0246] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 22.3 g DMPA followed by 12.6 g TEA was added to the
flask via the addition funnel, which was then rinsed with 7.7 g
acetone. The flask temperature was then raised again to 50.degree.
C. and held for 60 minutes.
[0247] With the temperature at 50.degree. C., 780 g deionized (DI)
water was added over 10 minutes, followed by mixture of 13.0 g EDA
(as a 6.25% solution in water) and 63.5 g TETA (as a 6.25% solution
in water) over 5 minutes, via the addition funnel, which was then
rinsed with 40 g water. The mixture was held at 50.degree. C. for 1
hr, then cooled to room temperature.
[0248] Acetone (-155.4 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 34.0% solids by weight.
[0249] For polyurethane dispersoid 7, the crosslinking was achieved
by the TETA.
[0250] Polyurethane Dispersoid 8 (PUD EX 8)
[0251] To a dry, alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 90.0 g Desmophene C 200, 245.5 g Terathane.RTM. 1400, 140 g
acetone and 0.04 g DBTL. The contents were heated to 40.degree. C.
and mixed well. 108.3 g IPDI was then added to the flask via the
addition funnel at 40.degree. C. over 60 min, with any residual
IPDI being rinsed from the addition funnel into the flask with 5.8
g acetone.
[0252] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 22.3 g DMPA followed by 12.6 g TEA was added to the
flask via the addition funnel, which was then rinsed with 12.5 g
acetone. The flask temperature was then raised again to 50.degree.
C. and held for 60 minutes.
[0253] With the temperature at 50.degree. C., 787 g deionized (DI)
water was added over 10 minutes, followed by 49 g TETA (as a 6.25%
solution in water) over 5 minutes, via the addition funnel, which
was then rinsed with 40 g water. The mixture was held at 50.degree.
C. for 1 hr, then cooled to room temperature.
[0254] Acetone (-157.3 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 34.0% solids by weight.
[0255] For polyurethane dispersoid 8, the crosslinking was achieved
by the TETA.
[0256] Polyurethane Dispersoid 9 (PUD EX 9)
[0257] To a dry alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 335.0 g of Desmophene C 200, 135 g acetone and 0.04 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 82 g IPDI
and 24.5 g Desmodur N3400 were then charged to the flask via the
addition funnel over 60 min, with any residual isocyanate being
rinsed from the addition funnel into the flask with 10.0 g
acetone.
[0258] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 22.3 g DMPA followed by 13.1 g TEA was then added
to the flask via the addition funnel, which was then rinsed with
10.0 g of acetone. The flask temperature was held at 50.degree. C.
until NCO % was 1.52 or less.
[0259] With temperature at 50.degree. C., 730.0 g DI water was
added over 10 minutes, followed by 96.0 g EDA (as a 6.25% solution
in water) over 5 minutes, via the addition funnel, which was then
rinsed with 40.0 g of water. The mixture was then held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0260] Acetone (-155 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 37% solids by weight.
[0261] For polyurethane dispersoid 9 the crosslinking was achieved
by the polyfunctional isocyanate component of the Desmodur
N3400.
[0262] Polyurethane Dispersoid 10 (PUD EX 10)
[0263] To a dry alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 335.0 g of Desmophene C 200, 138 g acetone and 0.04 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 90 g IPDI
and 27.0 g Desmodur N3400 were then charged to the flask via the
addition funnel over 60 min, with any residual isocyanate being
rinsed from the addition funnel into the flask with 10.0 g
acetone.
[0264] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 22.8 g DMPA followed by 13.3 g TEA was then added
to the flask via the addition funnel, which was then rinsed with
10.0 g of acetone. The flask temperature was held at 50.degree. C.
until NCO % was 1.8% or less.
[0265] With temperature at 50.degree. C., 716.0 g DI water was
added over 10 minutes, followed by 134.0 g EDA (as a 6.25% solution
in water) over 5 minutes, via the addition funnel, which was then
rinsed with 40.0 g of water. The mixture was then held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0266] Acetone (-158 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 39% solids by weight.
[0267] For polyurethane dispersoid 10 the crosslinking was achieved
by the polyfunctional isocyanate component of the Desmodur
N3400.
[0268] Polyurethane Dispersoid 11 (PUD EX 11)
[0269] To a dry alkali- and acid-free flask, equipped with an
addition funnel, a condenser, stirrer and a nitrogen gas line, was
added 335.0 g of Desmophene C 200, 142 g acetone and 0.04 g DBTL.
The contents were heated to 40.degree. C. and mixed well. 99 g IPDI
and 29.5 g Desmodur N3400 were then charged to the flask via the
addition funnel over 60 min, with any residual isocyanate being
rinsed from the addition funnel into the flask with 10.0 g
acetone.
[0270] The flask temperature was raised to 50.degree. C. and held
for 30 minutes. 23.4 g DMPA followed by 13.6 g TEA was then added
to the flask via the addition funnel, which was then rinsed with
10.0 g of acetone. The flask temperature was held at 50.degree. C.
until NCO % was 2.3% or less.
[0271] With temperature at 50.degree. C., 700.0 g DI water was
added over 10 minutes, followed by 174.0 g EDA (as a 6.25% solution
in water) over 5 minutes, via the addition funnel, which was then
rinsed with 40.0 g of water. The mixture was then held at
50.degree. C. for 1 hr, then cooled to room temperature.
[0272] Acetone (-162 g) was removed under vacuum, leaving a final
dispersoid of polyurethane with about 36% solids by weight.
[0273] For polyurethane dispersoid 11 the crosslinking was achieved
by the polyfunctional isocyanate component of the Desmodur
N3400.
[0274] Properties for Polyurethane Dispersoids 7-11
[0275] Polyurethane dispersoid physical properties and the THF
insolubles were measured and reported in Table 2.
2TABLE 2 Properties for Polyurethane Dispersoids 7-11 PUD PUD EX 7
PUD EX 8 PUD EX 9 PUD EX 10 EX 11 Viscosity (cps) 26 414 486 320 24
Solid % 34% 34% 37% 39% 36% pH 7.50 7.50 8.05 8.4 8.4 Particle Size
71 41 62 94 85 (nm) THF insolubles 14.7% 8% 14% 31% 39%
[0276] Set 1: Ink Stability
[0277] Inks of the instant invention generally are storage stable.
Thus, the instant inks can sustain elevated temperature in a closed
container for extended periods (e.g. 70.degree. C. for 7 days)
without substantial increase in viscosity or particle size.
3TABLE 3 Example for Stability Testing Black Dispersion (% pigment)
4.25% PUD EX 1 11% Dipropylene Glycol Methyl Ether 3% Glycerol 8%
Ethylene Glycol 11% Liponic .TM. EG-1 Surfynol .RTM. 104E 0.2%
Silwet .RTM. L77 0.2% Water (to 100%) Bal. Viscosity (cps) 7.94
[0278] Ink Example was heated at 70.degree. C. for 7 days and
physical properties were measured.
4TABLE 4 Storage stability Before aging After aging Viscosity 7.98
7.52 pH 7.81 7.81 Particle size D50(nm) 66 68 <202.4 nm 100%
97.5%
[0279] This ink was judged to be stable.
[0280] Set 2: Paper Printing Example; Black
[0281] The crosslinked polyurethane dispersoids were used to
produce a 3.46 cps viscosity black ink for testing on paper. Table
5 shows an ink composition that was based on PUD EX 8, and Table 6
shows ink properties. Ink was printed with an EPSON 980 printer on
Hammermill Tidal paper.
5TABLE 5 Ink composition for printing on plain paper; Ink Example A
PUD EX 8 1% Pigment, SDP black 6.5% Glycerol 9.0% Ethylene glycol
6.0% 1,6-Hexane diol 5.0% EDTA (5% solution) 2.0% BYK .RTM. 348
0.1% TEOA (10% solution) 1.0 Water Balance
[0282]
6TABLE 6 Ink properties for Printing on plain paper Viscosity (cps)
3.46 pH 8.15 Surface tension (dyne/cm) 25.11
[0283] Set 3: Paper Printing Example--Magenta and Yellow
[0284] The crosslinked polyurethane dispersoids were tested with
different colored inks. that were formulated for paper printing.
Table 7 shows the pigment dispersion source for a magenta and a
yellow ink. The ink compositions and ink properties for the magenta
and the yellow ink are shown in Table 8. Ink was printed with an
EPSON 980 printer on Hammermill Tidal paper or Xerox 4024
paper.
7TABLE 7 Colored Inks, Pigment Types and Polymeric Dispersants
Color Pigment type Polymeric Dispersant Yellow PY 74 BzMA//MAA
(13//10) Magenta PR 122 BzMA//MAA (13//10) Note: BzMA//MAA(13//10)
was prepared using the procedure "Preparation of Dispersant 2" from
previously incorporated US20030128246.
[0285]
8TABLE 8 Ink B and C Compositions and Properties. Ingredients,
amount, grams Ink B Ink C Magenta concentrate 29.15 Yellow
concentrate 9.49 PUD Ex 2 5.0 2.0 Glycerol 29.15 28.2
1,2-Hexanediol 18.46 5.97 Triethylene Glycol Monobutyl Ether 14.09
Diethylene glycol Monobutyl Ether 0.60 Ethylene Glycol 7.60
Triethanolamine 12.14 Proxel .RTM. GXL 0.97 0.4 BYK 348 1.21 1.0
Water 215.43 91.25 PH 9.34 8.7 Viscosity (cPs) 60 RPM @ 20.degree.
C. 4.36 3.4 Surface tension (dynes/cm) 29.96 26.45
[0286]
9TABLE 9 Washfastness Results HCP HCP HCP Xerox 4024 Xerox 4024
Xerox 4024 Ink 10 sec 1 min 5 min 10 sec 1 min 5 min Ink B OK OK OK
OK OK OK Ink C OK OK OK OK OK OK Note: OK means acceptable. NG
means not acceptable.
[0287] A comparative ink was tested with no added polyurethane
dispersoid and under each test condition the print failed. Set 4:
Paper printing example--Magenta with Various Levels of Polyurethane
Dispersoid
[0288] Three different concentrations of the polyurethane
dispersoid were tested for water-fastness.
10TABLE 10 Washfastness Results Ink B at % HCP HCP HCP Xerox 4024
Xerox 4024 Xerox 4024 concentration 10 sec 1 min 5 min 10 sec 1 min
5 min 0.25 NG NG NG NG NG NG 0.50 NG/OK NG/OK NG/OK OK OK OK 1.0 OK
OK OK OK OK OK
[0289] The NG/OK notation indicates that with tests of multiple
printed samples, some of the samples failed, that is, some of the
printed image was smeared or removed by the water and in other
samples the printed image was not affected by the water.
* * * * *