U.S. patent application number 16/399602 was filed with the patent office on 2019-08-22 for photo curable inks.
This patent application is currently assigned to Hewlett-Packard Development Company, L.P.. The applicant listed for this patent is Hewlett-Packard Development Company, L.P.. Invention is credited to Or Brandstein, Gregg A. Lane, Rodney David Stramel, Zhang-Lin Zhou.
Application Number | 20190256654 16/399602 |
Document ID | / |
Family ID | 56543886 |
Filed Date | 2019-08-22 |
![](/patent/app/20190256654/US20190256654A1-20190822-C00001.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00002.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00003.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00004.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00005.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00006.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00007.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00008.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00009.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00010.png)
![](/patent/app/20190256654/US20190256654A1-20190822-C00011.png)
View All Diagrams
United States Patent
Application |
20190256654 |
Kind Code |
A1 |
Zhou; Zhang-Lin ; et
al. |
August 22, 2019 |
PHOTO CURABLE INKS
Abstract
The present disclosure is drawn to polymeric photoactive agent,
photo curable inks containing the polymeric photoactive agent, and
methods of making the photo curable inks. The polymeric photoactive
agent can include a xanthone analog modified with a polyether chain
connecting to the xanthone analog through an ether linkage.
Inventors: |
Zhou; Zhang-Lin; (San Diego,
CA) ; Brandstein; Or; (San Diego, CA) ;
Stramel; Rodney David; (San Diego, CA) ; Lane; Gregg
A.; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hewlett-Packard Development Company, L.P. |
Spring |
TX |
US |
|
|
Assignee: |
Hewlett-Packard Development
Company, L.P.
Spring
TX
|
Family ID: |
56543886 |
Appl. No.: |
16/399602 |
Filed: |
April 30, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15540211 |
Jun 27, 2017 |
|
|
|
PCT/US2015/013016 |
Jan 27, 2015 |
|
|
|
16399602 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 65/48 20130101;
C09D 11/101 20130101; C09D 11/30 20130101; C08K 5/06 20130101; C08K
5/101 20130101; C09D 11/03 20130101 |
International
Class: |
C08G 65/48 20060101
C08G065/48; C08K 5/101 20060101 C08K005/101; C08K 5/06 20060101
C08K005/06; C09D 11/03 20060101 C09D011/03; C09D 11/101 20060101
C09D011/101; C09D 11/30 20060101 C09D011/30 |
Claims
1. A photo curable ink, comprising: a photo reactive binder; a
polymeric photoactive agent comprising a xanthone analog modified
with a polyether chain connecting to the xanthone analog through an
ether linkage; a co-photo initiator, a synergist, or combination
thereof; a colorant; and a liquid vehicle including co-solvent and
water.
2. The photo curable ink of claim 1, wherein the photo curable ink
has a pH of 7 to 12, the polymeric photoactive agent is stable in
the photo curable ink.
3. The photo curable ink of claim 1, wherein the photo curable ink
is photo curable using UV LED electromagnetic radiation.
4. The photo curable ink of claim 1, wherein the polymeric
photoactive agent is a sensitizer, and the ink comprises the
co-photo initiator.
5. The photo curable ink of claim 1, wherein the polymeric
photoactive agent is a photo initiator, and the ink comprises the
synergist.
6. The photo curable ink of claim 1, further comprising an
additional xanthone analog moiety connecting to an opposite end of
the polyether chain through an ether linkage.
7. The photo curable ink of claim 6, wherein the xanthone analog
moiety connecting the opposite end of the polyether chain through
the ether linkage has the general formula: ##STR00015## wherein
R.sub.1 to R.sub.4 are independently selected from the group
consisting of a hydrogen atom, an unsubstituted alkyl, a
substituted alkyl, an unsubstituted alkenyl, a substituted alkenyl,
an unsubstituted aryl, a substituted aryl, an unsubstituted
aralkyl, a substituted aralkyl, a halogen atom, --NO.sub.2,
--O--R.sub.d, --CO--R.sub.d, --CO--O--R.sub.d, --O--CO--R.sub.d,
--CO--NR.sub.d R.sub.e, --NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e, and a
perfluoroalkyl group, wherein R.sub.d, R.sub.e, and R.sub.f are
independently selected from the group consisting of a hydrogen
atom, an unsubstituted alkyl, a substituted alkyl, an unsubstituted
alkenyl, a substituted alkenyl, an unsubstituted aryl, a
substituted aryl, an unsubstituted aralkyl, and a substituted
aralkyl; and wherein X is selected from the group consisting of
--O--, --S--, --NH--, and --NR--, wherein R is selected from the
group consisting of CH.sub.3, CH.sub.2CH.sub.3, and
CH.sub.2CH.sub.2CH.sub.3.
8. The photo curable ink of claim 1, wherein the polyether chain is
selected from the group consisting of polyethylene glycol,
polypropylene glycol, and a copolymer of polyethylene glycol, and
polypropylene glycol.
9. The photo curable ink of claim 1, wherein the polymeric
photoactive agent has a general formula selected from the group
consisting of: ##STR00016## wherein R.sub.1 to R.sub.5 are
independently selected from the group consisting of a hydrogen
atom, an unsubstituted alkyl, a substituted alkyl, an unsubstituted
alkenyl, a substituted alkenyl, an unsubstituted aryl, a
substituted aryl, an unsubstituted aralkyl, a substituted aralkyl,
a halogen atom, --NO.sub.2, --O--R.sub.d, --CO--R.sub.d,
--CO--O--R.sub.d, --O--CO--R.sub.d, --CO--NR.sub.dR.sub.e,
--NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e, and a
perfluoroalkyl group, wherein R.sub.d, R.sub.e, and R.sub.f are
independently selected from the group consisting of a hydrogen
atom, an unsubstituted alkyl, a substituted alkyl, an unsubstituted
alkenyl, a substituted alkenyl, an unsubstituted aryl, a
substituted aryl, an unsubstituted aralkyl, and a substituted
aralkyl; wherein n is any integer from 5 to 200; and wherein X is
selected from the group consisting of --O--, --S--, --NH--, and
--NR--, wherein R is selected from the group consisting of
CH.sub.3, CH.sub.2CH.sub.3, and CH.sub.2CH.sub.2CH.sub.3.
10. The photo curable ink of claim 1, wherein the polymeric
photoactive agent has a molecular weight from about 500 to about
5000
11. The photo curable ink of claim 1, wherein the polymeric
photoactive agent has a general formula: ##STR00017## wherein n is
any integer from 10 to 25.
12. The photo curable ink of claim 1, wherein the polyether chain
is selected from the group consisting of PEG 550, PEG 600, and PEG
1000.
13. The photo curable ink of claim 1, wherein the polymeric
photoactive agent has a water solubility of at least 0.5 wt %.
14. The photo curable ink of claim 1, wherein the polymeric
photoactive agent has a water solubility of at least 0.5 wt %.
15. A method of making the photo curable ink of claim 1, comprising
admixing the photo reactive binder; the polymeric photoactive
agent; the co-photo initiator, the synergist, or combination
thereof; the colorant; and the liquid vehicle to form the photo
curable ink.
Description
[0001] The present Application is a Divisional Application of U.S.
patent application Ser. No. 15/540,211, filed Jun. 27, 2017, which
was a U.S. National Stage Application of International Application
No. PCT/US2015/013016, filed Jan. 27, 2015, each of which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Recently, curing of ink by radiation, and in particular
ultraviolet (UV) curing, has become popular. UV curable ink can be
cured after printing by application of UV light. Typically, UV
curable inks include monomers that form polymers by free radical
polymerization. The growing end of each polymer chain is a radical
that reacts with additional monomers, transferring the radical to
the end of the chain as each monomer is added. A photo initiator is
used to form the first radicals to begin the polymerization
process. The photo initiator is capable of absorbing UV light to
generate radicals to react with the monomers.
[0003] Two types of photo initiators can be used in UV curable
compositions. Type I photo initiators are unimolecular photo
initiators that undergo a hemolytic bond cleavage upon absorption
of UV light, forming radicals. Type II photo initiators are
bimolecular photo initiators. These are used as a system of a photo
initiator with a synergist, which can together form radicals upon
exposure to UV light. Some type II photo initiators react by
hydrogen abstraction from the synergist to the photo initiator.
DETAILED DESCRIPTION
[0004] The present disclosure is drawn to polymeric photoactive
agents that can be used as photo initiators, sensitizers, or both.
More specifically, the present disclosure provides polymeric
photoactive agents comprising a xanthone analog modified with a
polyether chain connecting to the xanthone analog through an ether
linkage. The polymeric photoactive agents can be water soluble and
stable in aqueous inks, such as aqueous thermal inkjet inks, for
example. The polymeric photoactive agents also resist migration in
the ink after curing. Thus, the polymeric photoactive agents of the
present disclosure overcome some of the drawbacks of other photo
initiators and sensitizers which do not behave in this positive
manner in aqueous systems. Some small molecular weight photo
initiators, such as isopropyl thioxanthone (ITX), can have unwanted
odor, toxicity, and migration in cured materials. On the other
hand, many polymeric photo initiators are not water soluble and are
difficult to formulate into aqueous inks. Furthermore, some
polymeric photo initiators using other types of linkages, such as
ester linkages, are not stable in the basic aqueous conditions that
are common in thermal inkjet inks.
[0005] The inkjet printing industry uses various types of inks,
such as oil-based inks, solvent-based (non-aqueous) inks,
water-based inks, and solid inks (which are melted in preparation
for dispensing). Solvent-based inks are fast drying, and as a
result, are widely used for industrial printing. When solvent-based
inks containing binders and other ingredients are jetted onto a
substrate, the solvent(s) partially or fully evaporate from the
ink, leaving the binder and other ingredients such as pigment
particles on the printed substrate in the form of a dry film.
During the drying process, the solvents, which are often volatile
organic compounds (VOC), emit vapors, and therefore, can pollute
the environment. The amount of pollution produced can increase
greatly with higher printing speeds or for wide format images,
where large amounts of ink are deposited onto a substrate. As a
result of this and other concerns, efforts related to preparing
inks that are environmentally friendly have moved some research in
the direction of water-based inks. However, radiation-curable (or
photon-curable) water-based ink compositions are noticeably limited
among available options due to their specific formulation
properties. Accordingly, the development of radiation
radiation-curable water-based ink compositions that exhibit, when
printed, specific desirable printing properties such as, for
example, jetting properties as well as improved adhesion would be
an advancement in the field of inkjet technology.
[0006] Accordingly, a polymeric photoactive agent can include a
xanthone analog modified with a polyether chain connecting to the
xanthone analog through an ether linkage. As used herein,
"xanthone" refers to the chemical compound having the Formula
1:
##STR00001##
[0007] Also, as used herein, "xanthone analog" refers to xanthone
itself and other chemical compounds having the same basic structure
as xanthone, but in which one or more atoms are replaced by
different atoms or moieties. For example, any of the hydrogen atoms
can be replaced by R groups or the ring structures themselves can
be replaced by other atoms. In some specific examples, the oxygen
atom that is a member of the central ring of the xanthone molecule
can be replaced by a sulfur atom, an --NH-- group, or an --NR--
group where R is CH.sub.3, CH.sub.2CH.sub.3, or
CH.sub.2CH.sub.2CH.sub.3. In other examples, hydrogens on the
aromatic rings can be replaced by carbon atoms connecting to form
additional aromatic rings. Thioxanthone is an example of a xanthone
analog in which this oxygen atom is replaced by a sulfur atom. As
used herein, "thioxanthone" refers to the molecule also called
thioxanthen-9-one, having the Formula 2:
##STR00002##
[0008] Other molecules with a similar shape can also be xanthone
analogs. Additional examples include compounds having Formulas
3-5:
##STR00003##
where R (in Formula 4 or 5) is CH.sub.3, CH.sub.2CH.sub.3, or
CH.sub.2CH.sub.2CH.sub.3, and X is --O--, --S--, --NH--, or
--NR--.
[0009] The polyether chain can be a polyglycol, paraformaldehyde,
or other polyether. For example, the polyether chain can be
polyethylene glycol (PEG), methoxypolyethylene glycol (MPEG),
polypropylene glycol (PPG), polybutylene glycol (PBG), or a
polyglycol copolymer. In one specific example, the polyether chain
can be selected from polyethylene glycol, polypropylene glycol, and
a copolymer of polyethylene glycol and polypropylene glycol.
Various molecular weights of polyether can be suitable. The type of
polyether chain and the molecular weight of the polyether chain can
in some cases affect the solubility of the final polymeric
photoactive agent. For example, a higher ratio of oxygen atoms to
carbon atoms in the polyether chain tends to make the polymeric
photoactive agent more soluble. The molecular weight of the
polyether chain can also affect the degree to which the polymeric
photoactive agent can migrate in a cured ink. Longer polyether
chains can make it more difficult for the polymeric photoactive
agent to move within a cured ink, thus decreasing migration.
Therefore, the type of polyether chain can be selected to give good
water solubility and low migration of the polymeric photoactive
agent in cured ink. In one example, the polyether chain can be a
polyglycol having at least 5 glycol monomer units, and more
specifically in one example, from 5 to 200 glycol monomer
units.
[0010] The polyether chain can connect to the xanthone analog
through an ether linkage. As used herein, connecting to the
xanthone analog through an ether linkage means that a single oxygen
atom is bonded both to a carbon atom in one of the aromatic side
rings of the xanthone analog and to a carbon atom in the polyether
chain. This ether linkage can be formed by a suitable reaction,
such as a substitution reaction or a condensation reaction.
[0011] The xanthone analog, polyether chain, and ether linkage do
not necessarily make up the entire polymeric photoactive agent. For
example, additional groups can be attached along the polyether
chain or at the opposite end of the polyether chain. In some cases,
one or more additional xanthone analog moieties can be attached to
the polyether chain. These additional xanthone analog moieties can
connect to the polyether chain through ether linkages. In one
example, an additional xanthone analog moiety can connect to an
opposite end of the polyether chain through an ether linkage. In
other examples, the polyether chain can have multiple branches and
each branch can terminate with a xanthone analog moiety connected
to the polyether chain through an ether linkage. Specific examples
of such polymeric photoactive agents are described in detail
below.
[0012] In some examples, the xanthone analog with the ether linkage
can have a general formula according to Formula 6:
##STR00004##
[0013] In Formula 6, the ether linkage is illustrated as an oxygen
atom bonded to the right side ring of the xanthone analog. The
oxygen atom can be bonded to any of the available carbon atoms in
the right side ring by replacing a hydrogen atom. The groups
R.sub.1, R.sub.2, R.sub.2, and R.sub.4 can be independently
selected from: a hydrogen atom, an unsubstituted alkyl, a
substituted alkyl, an unsubstituted alkenyl, a substituted alkenyl,
an unsubstituted aryl, a substituted aryl, an unsubstituted
aralkyl, a substituted aralkyl, a halogen atom, --NO.sub.2,
--O--R.sub.d, --CO--R.sub.d, --CO--O--R.sub.d, --O--CO--R.sub.d,
--CO--NR.sub.dR.sub.e, --NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e, and a
perfluoroalkyl group, wherein R.sub.d, R.sub.e, and R.sub.f are
independently selected from: a hydrogen atom, an unsubstituted
alkyl, a substituted alkyl, an unsubstituted alkenyl, a substituted
alkenyl, an unsubstituted aryl, a substituted aryl, an
unsubstituted aralkyl, and a substituted aralkyl. In one specific
example, R.sub.1 to R.sub.4 can each be a hydrogen atom. The group
X can be --O--, --S--, --NH--, or --NR-- where R is CH.sub.3,
CH.sub.2CH.sub.3, or CH.sub.2CH.sub.2CH.sub.3. Formula 6
illustrates only the xanthone analog with the ether linkage. A
complete polymeric photoactive agent can be formed by combining a
xanthone analog and ether linkage as in Formula 3 with a polyether
chain. The polyether chain can be bonded to the oxygen atom forming
the ether linkage.
[0014] In some examples, the polymeric photoactive agent can have a
general formula according one of Formulas 7-10:
##STR00005##
[0015] In each of Formulas 7-10, the groups R.sub.1, R.sub.2,
R.sub.2, R.sub.4, and R.sub.5 can independently be a hydrogen atom,
an unsubstituted alkyl, a substituted alkyl, an unsubstituted
alkenyl, a substituted alkenyl, an unsubstituted aryl, a
substituted aryl, an unsubstituted aralkyl, a substituted aralkyl,
a halogen atom, --NO.sub.2, --O--R.sub.d, --CO--R.sub.d,
--CO--O--R.sub.d, --O--CO--R.sub.d, --CO--NR.sub.dR.sub.e,
--NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e, or a
perfluoroalkyl group. In these examples, R.sub.d, R.sub.e, and
R.sub.f can independently be a hydrogen atom, an unsubstituted
alkyl, a substituted alkyl, an unsubstituted alkenyl, a substituted
alkenyl, an unsubstituted aryl, a substituted aryl, an
unsubstituted aralkyl, or a substituted aralkyl. In one specific
example, R.sub.1 to R.sub.5 can each be a hydrogen atom. The number
of monomer units n can be any integer from 5 to 200. The group X
can be --O--, --S--, --NH--, or --NR-- where R is CH.sub.3,
CH.sub.2CH.sub.3, or CH.sub.2CH.sub.2CH.sub.3.
[0016] As shown in Formulas 7-10, the polymeric photoactive agent
can include 1, 2, 3, or 4 xanthone analog moieties connected to a
branching polyether chain. In other examples, the polyether chain
can have more than 4 branches terminating in xanthone analog
moieties.
[0017] In one example, the polymeric photoactive agent can have a
general formula according to Formula 11:
##STR00006##
[0018] In the specific example described by Formula 11, n can be
any integer, e.g., 0 to 200, and in one example, the sum of m, n.
and p can be from 10 to 25.
[0019] The molecular weight of the polymeric photoactive agent can
affect its degree of migration in cured ink. For example, a
polymeric photoactive agent with a weight average molecular weight
(Mw) of about 500 Mw or more can have reduced migration in cured
ink compared with a small molecule photo initiator or sensitizer.
Migration can be further reduced by increasing the molecular weight
of the polymeric photoactive agent to about 1000 Mw or more. In one
example, the polymeric photoactive agent can have a molecular
weight from about 500 Mw to about 5000 Mw. Polyethers of various
molecular weights are available, allowing for the production of
polymeric photoactive agents with various molecular weights. In
some examples, the polyether chain can be selected from PEG 550,
PEG 600, and PEG 1000. In polymeric photoactive agents having
multiple xanthone analog moieties, a smaller molecular weight
polyether chain can be used while still maintaining a high overall
molecular weight of the polymeric photoactive agents. The molecular
weight of the polymeric photoactive agent can also be changed by
adding R groups to the xanthone analog. It is noted that when
referring to "R groups" generically herein, this term is defined to
include at least H and organic side chain side groups and other
specific constituents described and defined elsewhere herein, e.g.,
R.sub.1, R.sub.2, R.sub.3,R.sub.4, R.sub.5,R.sub.6, R.sub.d,
R.sub.e, R.sub.f, etc.
[0020] The molecular weight of the polymeric photoactive agent can
also affect its solubility in water. In some cases, the polyether
chain can be a water soluble polyether. Although the xanthone
analog alone can be insoluble in water, adding the soluble
polyether chain can make the entire polymeric photoactive agent
soluble. In such cases, the soluble polyether can have a sufficient
molecular weight so that its solubility properties overcome the
insolubility of the xanthone analog. In other cases, water soluble
R groups can be added to the xanthone analog to increase the
solubility of the polymeric photoactive agent. In one example, the
polymeric photoactive agent can have a water solubility of at least
0.5 wt %.
[0021] Typical aqueous ink jet inks can have a pH in the range of 7
to 12. Some commercially available photo initiators and sensitizers
with ester linkages can break down in such basic conditions. The
ether linkage in the polymeric photoactive agents according to the
present disclosure can be stable under these conditions. In some
examples, the polymeric photoactive agent can be stable in water up
to a pH from 7 to 12. In other examples, the polymeric photoactive
agent can be stable in water up to a pH of 8 or higher. As used
herein, "stable" refers to the ability of the polymeric photoactive
agent to have a shelf life of at least 1 year. Typically, aqueous
ink jet inks can have a shelf life of greater than 1 year, greater
than 2 years, or longer.
[0022] A general pathway for forming a polymeric photoactive agent
in accordance with an example of the present disclosure is shown in
Formula 12:
##STR00007##
[0023] In the pathway shown in Formula 12, R.sub.1 to R.sub.5 each
independently represent a hydrogen atom, a substituted or
unsubstituted alkyl, alkenyl, aryl or aralkyl group or a group
selected from a halogen atom, --NO.sub.2, --O--R.sub.d,
--CO--R.sub.d, --CO--O--R.sub.d, --O--CO--R.sub.d,
--CO--NR.sub.dR.sub.e, --NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e or a
perfluoroalkyl group. R.sub.d, R.sub.e and R.sub.f independently
represent a hydrogen or a substituted or unsubstituted alkyl,
alkenyl, aryl or aralkyl group. The number of monomer units n can
be any integer from 5 to 200. The group X can be --O--, --S--,
--NH--, or --NR-- where R is CH.sub.3, CH.sub.2CH.sub.3, or
CH.sub.2CH.sub.2CH.sub.3. The group Y can be a leaving group such
as --Cl, --Br, --I, --OTs, or --OTf.
[0024] According to this pathway, a monosubstituted polyethylene
glycol ether (1) is reacted with a leaving group to form a leaving
group modified polyethylene glycol (2). Various reagents can be
used to add the leaving group. For example, a halogenation reagent
can be used to add --Cl, --Br, or --I leaving groups; a tosylation
reagent can be used to add a --OTs leaving group; and a triflating
reagent can be used to add a --OTf leaving group. A
hydroxyl-modified xanthone analog (3) is reacted with NaOH to form
a corresponding sodium salt (4). The sodium salt is then reacted
with the leaving group modified polyethylene glycol (2) to form the
polymeric photoactive agent. Lines leading to the center of
aromatic rings in the hydroxyl-modified xanthone analog (3), the
sodium salt (4), and the final polymeric photoactive agent signify
that the group can be attached at any available location on the
ring.
[0025] Another example of a general pathway for forming a polymeric
photoactive agent in accordance with the present disclosure is
shown in Formula 13:
##STR00008##
[0026] In the pathway shown in Formula 13, R.sub.1 to R.sub.4 each
independently represent a hydrogen atom, a substituted or
unsubstituted alkyl, alkenyl, aryl or aralkyl group or a group
selected from a halogen atom, --NO.sub.2, --O--R.sub.d,
--CO--R.sub.d, --CO--O--R.sub.d, --O--CO--R.sub.d,
--CO--NR.sub.dR.sub.e, --NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e or a
perfluoroalkyl group. R.sub.d, R.sub.e and R.sub.f independently
represent a hydrogen or a substituted or unsubstituted alkyl,
alkenyl, aryl or aralkyl group. The number of monomer units n can
be any integer from 5 to 200. The group X can be --O--, --S--,
--NH--, or --NR-- where R is CH.sub.3, CH.sub.2CH.sub.3, or
CH.sub.2CH.sub.2CH.sub.3. The group Y can be a leaving group such
as --Cl, --Br, --I, --OTs, or --OTf.
[0027] According to this pathway, polyethylene glycol (5) is
reacted with a leaving group reagent to form a leaving group
modified polyethylene glycol (6). A hydroxyl-modified xanthone
analog (3) is reacted with NaOH to form a corresponding sodium salt
(4). The sodium salt is then reacted with the leaving group
modified polyethylene glycol (6) to form the polymeric photoactive
agent. Lines leading to the center of aromatic rings in the
hydroxyl-modified xanthone analog (3), the sodium salt (4), and the
final polymeric photoactive agent signify that the group can be
attached at any available location on the ring.
[0028] A further example of a general pathway for forming a
polymeric photoactive agent keeping with the present disclosure is
shown in Formula 14:
##STR00009##
[0029] In the pathway shown in Formula 14, R.sub.1 to R.sub.5 each
independently represent a hydrogen atom, a substituted or
unsubstituted alkyl, alkenyl, aryl or aralkyl group or a group
selected from a halogen atom, --NO.sub.2, --O--R.sub.d,
--CO--R.sub.d, --CO--O--R.sub.d, --O--CO--R.sub.d,
--CO--NR.sub.dR.sub.e, --NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e or a
perfluoroalkyl group. R.sub.d, R.sub.e and R.sub.f independently
represent a hydrogen or a substituted or unsubstituted alkyl,
alkenyl, aryl or aralkyl group. The number of monomer units n can
be any integer from 5 to 200. The group X can be --O--, --S--,
--NH--, or --NR-- where R is CH.sub.3, CH.sub.2CH.sub.3, or
CH.sub.2CH.sub.2CH.sub.3. The group Y can be a leaving group such
as --Cl, --Br, --I, --OTs, or --OTf.
[0030] According to this pathway, a glycerol polyethylene glycol
derivative (7) is reacted with a leaving group reagent to form a
leaving group modified glycerol polyethylene glycol derivative (8).
A hydroxyl-modified xanthone analog (3) is reacted with NaOH to
form a corresponding sodium salt (4). The sodium salt is then
reacted with the leaving group modified glycerol polyethylene
glycol derivative (8) to form the polymeric photoactive agent.
Lines leading to the center of aromatic rings in the
hydroxyl-modified xanthone analog (3), the sodium salt (4), and the
final polymeric photoactive agent signify that the group can be
attached at any available location on the ring.
[0031] Yet another example of a general pathway for forming a
polymeric photoactive agent in accordance with the present
disclosure is shown in Formula 15:
##STR00010##
[0032] In the pathway shown in Formula 15, R.sub.1 to R.sub.4 each
independently represent a hydrogen atom, a substituted or
unsubstituted alkyl, alkenyl, aryl or aralkyl group or a group
selected from a halogen atom, --NO.sub.2, --O--R.sub.d,
--CO--R.sub.d, --CO--O--R.sub.d, --O--CO--R.sub.d,
--CO--NR.sub.dR.sub.e, --NR.sub.dR.sub.e, --NR.sub.d--CO--R.sub.e,
--NR.sub.d--CO--O--R.sub.e, --NR.sub.d--CO--NR.sub.eR.sub.f,
--SR.sub.d, --SO--R.sub.d, --SO.sub.2--R.sub.d,
--SO.sub.2--O--R.sub.d, --SO.sub.2NR.sub.dR.sub.e or a
perfluoroalkyl group. R.sub.d, R.sub.e and R.sub.f independently
represent a hydrogen or a substituted or unsubstituted alkyl,
alkenyl, aryl or aralkyl group. The number of monomer units n can
be any integer from 5 to 200. The group X can be --O--, --S--,
--NH--, or --NR-- where R is CH.sub.3, CH.sub.2CH.sub.3, or
CH.sub.2CH.sub.2CH.sub.3. The group Y can be a leaving group such
as --Cl, --Br, --I, --OTs, or --OTf.
[0033] According to this pathway, a pentaerythritol polyethylene
glycol derivative (9) is reacted with a leaving group to form a
leaving group modified pentaerythritol polyethylene glycol
derivative (10). A hydroxyl-modified xanthone analog (3) is reacted
with NaOH to form a corresponding sodium salt (4). The sodium salt
is then reacted with the leaving group modified glycerol
polyethylene glycol derivative (10) to form the polymeric
photoactive agent. Lines leading to the center of aromatic rings in
the hydroxyl-modified xanthone analog (3), the sodium salt (4), and
the final polymeric photoactive agent signify that the group can be
attached at any available location on the ring.
[0034] Formula 16 illustrates a detailed synthetic pathway for one
example of a polymeric photoactive agent in accordance with the
present disclosure:
##STR00011##
[0035] According to this pathway, phenol (12) and 2-thiosalicylic
acid (11) undergo a condensation reaction in concentrated sulfuric
acid under heated conditions to yield 2-hydroxythioxanthen-9-one
(3). The 2-hydroxythioxanthen-9-one is treated with sodium
hydroxide in THF under reflux to give the corresponding sodium salt
(4). Mono-methyl polyethylene glycol ether (13) is reacted with
thionyl chloride in the presence of DMF to give chloro mono-methyl
polyethylene glycol ether (14). A substitution reaction of the
sodium salt (4) with the chloro compound (14) under reflux gives
the desired polymeric photoactive agent (15).
[0036] An alternative pathway for synthesizing the same polymeric
photoactive agent is shown in Formula 17:
##STR00012##
[0037] In this pathway, mono-methyl polyethylene glycol ether (13)
is reacted with p-toluenesulfonyl chloride in the presence of
pyridine to give mono-methyl polyethylene glycol ether tosylate
(16). Then, a substation reaction of sodium salt (4) with the
mono-methyl polyethylene glycol ether tosylate (16) gives the
desired polymeric photoactive agent (15).
[0038] A detailed synthetic pathway for forming another example of
a polymeric photoactive agent in accordance with the present
disclosure is shown in Formula 18:
##STR00013##
[0039] In this pathway, polyethylene glycol (17) reacts with
thionyl chloride in the presence of DMF to give dichloro
polyethylene glycol (18). Then, a substitution reaction of sodium
salt (4) with the dichloro polyethylene glycol (18) gives the
desired polymeric photoactive agent (19).
[0040] Formula 19 illustrates an alternate pathway for forming the
same polymeric photoactive agent:
##STR00014##
[0041] According to this pathway, polyethylene glycol (17) is
reacted with p-toluenesulfonyl chloride in the presence of pyridine
to give polyethylene glycol di-tosylate (20). Then, a substitution
reaction of sodium salt (4) and the polyethylene glycol di-tosylate
(20) gives the desired polymeric photoactive agent (19).
[0042] The present disclosure also extends to photo curable inks.
In some examples, a UV curable ink or an LED curable ink can be
used, e.g., UV and/or LED curable ink. These inks can include a
photo reactive binder, e.g., UV and/or LED, a polymeric photoactive
agent, co-photo initiator or an synergist, a colorant, and a liquid
vehicle including a co-solvent and water. The polymeric photoactive
agent can be a xanthone analog modified with a polyether chain
connecting to the xanthone analog through an ether linkage. In
various aspects, the polymeric photo active agent can act as a
photo initiator with the synergist, or it can act as a sensitizer
for a co-photo initiator, for example.
[0043] In some cases, the photo reactive binder can include a UV
curable polyurethane and hydrophobic radiation-curable monomers. In
one example, the photo reactive binder can include a water
dispersible (meth)acrylated polyurethane, such as NeoRad.RTM. R-441
by NeoResins (Avecia). Other examples of photo (UV) reactive
binders can include Ucecoat.RTM. 7710, Ucecoat.RTM. 7655 (available
from Cytec), Neorad.RTM. R-440, Neorad.RTM. R-441, Neorad.RTM.
R-447, Neorad.RTM. R-448 (available from DSM NeoResins),
Bayhydrol.RTM. UV 2317, Bayhydrol.RTM. UV VP LS 2348 (available
from Bayer), Lux 430, Lux 399, Lux 484 (available from Alberdingk
Boley), Laromer.RTM. LR 8949, Laromer.RTM. LR 8983, Laromer.RTM. PE
22WN, Laromer.RTM. PE 55WN, Laromer.RTM. UA 9060 (available from
BASF), or combinations thereof.
[0044] The polymeric photoactive agents of the present disclosure
can act as type II photo initiators. The photo curable ink can
include a synergist so that the photo initiator and synergist
together can generate radicals during photo curing, e.g., UV curing
or LED curing or UV LED curing. In some examples, the synergist can
be an amine synergist. The amine synergist can be a tertiary amine
compound. In one example, the amine synergist can be a polymeric
amine synergist such as a derivative of aniline and a polyether
amine such as Jeffamine.RTM. 900. In other examples, the amine
synergist can be trimethylamine, triethanolamine,
methyldiethanolamine, phenyldiethanolamine,
N,N,N',N'-tetra(hydroxylethyl)ethylenediamine, dimethylaminoethyl
acrylate, dimethylaminoethyl methacrylate, ethyl
dimethylaminobenzoate, or combinations thereof.
[0045] The polymeric photoactive agents of the present disclosure
can act as the primary photo initiator in the photo curable ink, or
they can act as a sensitizer for another co-photo initiator.
Therefore, the photo curable ink can in some cases include a second
photo initiator in addition to the polymeric photoactive agents
disclosed herein, wherein the polymeric photoactive agent can act
as a sensitizer in some respects. Examples of radical co-photo
initiators include, by way of illustration and not limitation,
1-hydroxy-cyclohexylphenylketone, benzophenone,
2,4,6-trimethylbenzo-phenone, 4-methylbenzophenone,
diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl
bis(2,4,6trimethylbenzoyl)phosphine oxide,
2-hydroxy-2-methyl-1-phenyl-1-propanone, benzyl-dimethyl ketal,
2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropan-l-one, or
combinations thereof. Non-limiting examples of additional photo
initiators include alpha amino ketone UV photo initiators such as
Ciba.RTM. Irgacure.RTM. 907, Ciba.RTM. Irgacure.RTM. 369, and
Ciba.RTM. Irgacure.RTM. 379; bis acylphosphine oxide (BAPO) UV
photo initiators such as Irgacure.RTM. 819, Darocur.RTM. 4265, and
Darocur.RTM. TPO; alpha hydroxy ketone UV photo initiators such as
Irgacure.RTM. 184 and Darocur.RTM. 1173; including photo initiators
with or without sensitizers such as Darocur.RTM. ITX (2-isopropyl
thioxanthone).
[0046] The colorant in the photo curable ink can be a pigment, a
dye, or a combination thereof. In some examples, the colorant can
be present in an amount from 0.5 wt % to 10 wt % in the photo
curable ink. In one example, the colorant can be present in an
amount from 1 wt % to 5 wt %. In another example, the colorant can
be present in an amount from 5 wt % to 10 wt %.
[0047] In some examples, the colorant can be a dye. The dye can be
nonionic, cationic, anionic, or a mixture of nonionic, cationic,
and/or anionic dyes. Specific examples of dyes that can be used
include, but are not limited to, Sulforhodamine B, Acid Blue 113,
Acid Blue 29, Acid Red 4, Rose Bengal, Acid Yellow 17, Acid Yellow
29, Acid Yellow 42, Acridine Yellow G, Acid Yellow 23, Acid Blue 9,
Nitro Blue Tetrazolium Chloride Monohydrate or Nitro BT, Rhodamine
6G, Rhodamine 123, Rhodamine B, Rhodamine B Isocyanate, Safranine
O, Azure B, and Azure B Eosinate, which are available from
Sigma-Aldrich Chemical Company (St. Louis, Mo.). Examples of
anionic, water-soluble dyes include, but are not limited to, Direct
Yellow 132, Direct Blue 199, Magenta 377 (available from Ilford AG,
Switzerland), alone or together with Acid Red 52. Examples of
water-insoluble dyes include azo, xanthene, methine, polymethine,
and anthraquinone dyes. Specific examples of water-insoluble dyes
include Orasol.RTM. Blue GN, Orasol.RTM. Pink, and Orasol.RTM.
Yellow dyes available from Ciba-Geigy Corp. Black dyes may include,
but are not limited to, Direct Black 154, Direct Black 168, Fast
Black 2, Direct Black 171, Direct Black 19, Acid Black 1, Acid
Black 191, Mobay Black SP, and Acid Black 2.
[0048] In other examples, the colorant can be a pigment. The
pigment can be self-dispersed with a polymer, oligomer, or small
molecule; or can be dispersed with a separate dispersant. Suitable
pigments include, but are not limited to, the following pigments
available from BASF: Paliogen.RTM. Orange, Heliogen.RTM. Blue L
6901F, Heliogen.RTM. Blue NBD 7010, Heliogen.RTM. Blue K 7090,
Heliogen.RTM. Blue L 7101F, Paliogen.RTM. Blue L 6470,
Heliogen.RTM. Green K 8683, and Heliogen.RTM. Green L 9140. The
following black pigments are available from Cabot: Monarch.RTM.
1400, Monarch.RTM. 1300, Monarch.RTM. 1100, Monarch.RTM. 1000,
Monarch.RTM. 900, Monarch.RTM. 880, Monarch.RTM. 800, and
Monarch.RTM. 700. The following pigments are available from CIBA:
Chromophtal.RTM. Yellow 3G, Chromophtal.RTM. Yellow GR,
Chromophtal.RTM. Yellow 8G, Igrazin.RTM. Yellow 5GT, Igralite.RTM.
Rubine 4BL, Monastral.RTM. Magenta, Monastral.RTM. Scarlet,
Monastral.RTM. Violet R, Monastral.RTM. Red B, and Monastral.RTM.
Violet Maroon B. The following pigments are available from Degussa:
Printex.RTM. U, Printex.RTM. V, Printex.RTM. 140U, Printex.RTM.
140V, Color Black FW 200, Color Black FW 2, Color Black FW 2V,
Color Black FW 1, Color Black FW 18, Color Black S 160, Color Black
S 170, Special Black 6, Special Black 5, Special Black 4A, and
Special Black 4. The following pigment is available from DuPont:
Tipure.RTM. R-101. The following pigments are available from
Heubach: Dalamar.RTM. Yellow YT-858-D and Heucophthal Blue G
XBT-583D. The following pigments are available from Clariant:
Permanent Yellow GR, Permanent Yellow G, Permanent Yellow DHG,
Permanent Yellow NCG-71, Permanent Yellow GG, Hansa Yellow RA,
Hansa Brilliant Yellow 5GX-02, Hansa Yellow-X, Novoperm.RTM. Yellow
HR, Novoperm.RTM. Yellow FGL, Hansa Brilliant Yellow 10GX,
Permanent Yellow G3R-01, Hostaperm.RTM. Yellow H4G, Hostaperm.RTM.
Yellow H3G, Hostaperm.RTM. Orange GR, Hostaperm.RTM. Scarlet GO,
and Permanent Rubine F6B. The following pigments are available from
Mobay: Quindo.RTM. Magenta, Indofast.RTM. Brilliant Scarlet,
Quindo.RTM. Red R6700, Quindo.RTM. Red R6713, and Indofast.RTM.
Violet. The following pigments are available from Sun Chemical:
L74-1357 Yellow, L75-1331 Yellow, and L75-2577 Yellow. The
following pigments are available from Columbian: Raven.RTM. 7000,
Raven.RTM. 5750, Raven.RTM. 5250, Raven.RTM. 5000, and Raven.RTM.
3500. The following pigment is available from Sun Chemical: LHD9303
Black. Any other pigment and/or dye can be used that is useful in
modifying the color of the UV curable ink. Additionally, the
colorant can include a white pigment such as titanium dioxide, or
other inorganic pigments such as zinc oxide and iron oxide.
[0049] The components of the photo curable ink can be selected to
give the ink good ink jetting performance. Besides the curable
binder, photo reactive photoactive agents, and the colorant, the
photo curable ink can also include a liquid vehicle. Liquid vehicle
formulations that can be used in the photo curable ink can include
water and one or more co-solvents present in total at from 1 wt %
to 50 wt %, depending on the jetting architecture. Further, one or
more non-ionic, cationic, and/or anionic surfactant can be present,
ranging from 0.01 wt % to 20 wt % (if present). In one example, the
surfactant can be present in an amount from 5 wt % to 20 wt %. The
liquid vehicle can also include dispersants in an amount from 5 wt
% to 20 wt %. The balance of the formulation can be purified water,
or other vehicle components such as biocides, viscosity modifiers,
materials for pH adjustment, sequestering agents, preservatives,
and the like. In one example, the liquid vehicle can be
predominantly water.
[0050] Classes of co-solvents that can be used can include organic
co-solvents including aliphatic alcohols, aromatic alcohols, diols,
glycol ethers, polyglycol ethers, caprolactams, formamides,
acetamides, and long chain alcohols. Examples of such compounds
include primary aliphatic alcohols, secondary aliphatic alcohols,
1,2-alcohols, 1,3-alcohols, 1,5-alcohols, ethylene glycol alkyl
ethers, propylene glycol alkyl ethers, higher homologs
(C.sub.6-C.sub.12) of polyethylene glycol alkyl ethers, N-alkyl
caprolactams, unsubstituted caprolactams, both substituted and
unsubstituted formamides, both substituted and unsubstituted
acetamides, and the like. Specific examples of solvents that can be
used include, but are not limited to, 2-pyrrolidinone,
N-methylpyrrolidone, 2-hydroxyethyl-2-pyrrolidone,
2-methyl-1,3-propanediol, tetraethylene glycol, 1,6-hexanediol,
1,5-hexanediol and 1,5-pentanediol.
[0051] One or more surfactants can also be used, such as alkyl
polyethylene oxides, alkyl phenyl polyethylene oxides, polyethylene
oxide block copolymers, acetylenic polyethylene oxides,
polyethylene oxide (di)esters, polyethylene oxide amines,
protonated polyethylene oxide amines, protonated polyethylene oxide
amides, dimethicone copolyols, substituted amine oxides, and the
like. The amount of surfactant added to the formulation of this
disclosure may range from 0.01 wt % to 20 wt %. Suitable
surfactants can include, but are not limited to, liponic esters
such as Tergitol.TM. 15-S-12, Tergitol.TM. 15-S-7 available from
Dow Chemical Company, LEG-1 and LEG-7; Triton.TM. X-100; Triton.TM.
X-405 available from Dow Chemical Company; LEG-1, and sodium
dodecylsulfate.
[0052] Consistent with the formulation of this disclosure, various
other additives can be employed to optimize the properties of the
ink composition for specific applications. Examples of these
additives are those added to inhibit the growth of harmful
microorganisms. These additives may be biocides, fungicides, and
other microbial agents, which are routinely used in ink
formulations. Examples of suitable microbial agents include, but
are not limited to, NUOSEPT.RTM. (Nudex, Inc.), UCARCIDE.TM. (Union
carbide Corp.), VANCIDE.RTM. (R.T. Vanderbilt Co.), PROXEL.RTM.
(ICI America), and combinations thereof.
[0053] Sequestering agents, such as EDTA (ethylene diamine tetra
acetic acid), may be included to eliminate the deleterious effects
of heavy metal impurities, and buffer solutions may be used to
control the pH of the ink. From 0.01 wt % to 2 wt %, for example,
can be used if present. Viscosity modifiers and buffers may also be
present, as well as other additives to modify properties of the ink
as desired. Such additives can be present at from 0.01 wt % to 20
wt % if present.
[0054] Table 1 shows the composition of an example of a photo
curable ink, e.g., UV LED curable ink, formulation example in
accordance with the present disclosure. The ink can be formulated
by mixing these ingredients or by other formulations. The pH of the
ink can then be adjusted. In one example, the ingredients can be
stirred for 30 minutes, and then aqueous potassium hydroxide can be
added to adjust the pH to 7 to 12, or in one example, about 8.5. It
is noted that though water concentrations are listed as "balance,"
it is understood that the balance of components could included
other liquid vehicle components or minor amounts of solids often
present in inkjet ink compositions.
TABLE-US-00001 TABLE 1 Component Weight Percent Photo reactive
binder 1-20% (UV reactive polymer) Polymeric photoactive agent
0.15-5% (sensitizer or photo initiator) Co-photo initiator *0-10%
Synergist *0-5% Surfactant 0-20% Anti-kogation agent 0-5% Colorant
0.5-10% Organic Co-solvent 0.1-50% Water Balance *As noted, when
the polymeric photo active agent is included as a sensitizer, the
co-photo initiator is at greater than 0%. When the polymeric photo
active agent is included as a photo initiator, the synergist is at
greater than 0%. All three components can likewise be present, i.e.
the polymeric photo active agent, the co-photo initiator, and the
synergist.
[0055] The photo curable ink can be used to print on a broad
selection of substrates including untreated plastics, flexible as
well as rigid, porous substrates such as paper, cardboard, foam
board, textile, and others. The ink has a good adhesion on a
variety of substrates. The photo curable ink also has a good
viscosity, enabling good printing performances and enables the
ability to formulate inks suitable for inkjet application. In some
examples, the ink can be formulated for thermal inkjet printing.
The photo curable ink composition of the present disclosure enables
high printing speed and is very well suited for a use in digital
inkjet printing.
[0056] The polymeric photoactive agents of the present disclosure
can be stable in aqueous environments at pH from 7 to 12 or higher.
Thus, the photo curable ink can be formulated to have a pH from 7
to 12. In some examples, the photo curable ink can have a pH of 8
to 12. In one specific example, the photo curable ink can have a pH
of about 8.5.
[0057] The polymeric photoactive agent can exhibit less migration
in cured ink compared with small molecule photo initiators. The
photo curable binder in the ink can comprise polymers or monomers
that polymerize or cross-link during the curing process. As the
binder cures, the polymeric photoactive agent can become locked
into the cured binder due to the long polyether chain of the
polymeric photoactive agent. Therefore, the photo curable ink can
be formulated so that there is little or no migration of the
polymeric photoactive agent in the ink after curing.
[0058] The present disclosure also extends to a method of making a
photo curable ink. The method includes mixing a photo reactive
binder; a polymeric photoactive agent comprising a xanthone analog
modified with a polyether chain connecting to the xanthone analog
through an ether linkage; a co-photo initiator, a synergist, or
combination thereof; a colorant; and a liquid vehicle including
co-solvent and water. The photo curable ink can be UV curable, and
in one specific example, UV LED curable. In one example, the method
can also include adjusting the pH of the ink to be from 7 to 12. In
another example, the method can include adjusting the pH of the ink
to be 8 or higher.
[0059] It is to be understood that this disclosure is not limited
to the particular process steps and materials disclosed herein
because such process steps and materials may vary somewhat. It is
also to be understood that the terminology used herein is used for
the purpose of describing particular examples only. The terms are
not intended to be limiting because the scope of the present
disclosure is intended to be limited only by the appended claims
and equivalents thereof.
[0060] It is noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the" include
plural referents unless the context clearly dictates otherwise.
[0061] As used herein, "photoactive agent" refers to materials that
participate in the initiation of photo polymerization, particularly
materials that act as a photo initiator or a sensitizer for a photo
initiator. The polymeric photoactive agents disclosed herein can be
used either as a photo initiator or as a sensitizer for another
photo initiator. In some systems, the polymeric photoactive agent
can act as both a photo initiator and a sensitizer.
[0062] As used herein, "UV curable" refers to compositions that can
be cured by exposure to ultraviolet light from any UV source such
as a mercury vapor lamp, UV LED source, or the like. Mercury vapor
lamps emit high intensity light at wavelengths from 240 nm to 270
nm and 350 nm to 380 nm. "LED curable" refers to compositions that
can be cured either by ultraviolet light from an ultraviolet LED.
Ultraviolet LEDs emit light at specific wavelengths. For example,
ultraviolet LEDs are available at 365 nm and 395 nm wavelengths,
among others. The term "photo curable" refers generally to
compositions that can be cured by exposure to light from any
wavelength suitable for the composition being cured. Typically, the
photo curable composition will be UV curable, and in some cases UV
LED curable.
[0063] As used herein, "liquid vehicle" or "ink vehicle" refers to
a liquid fluid in which colorant is placed to form an ink. A wide
variety of ink vehicles may be used with the systems and methods of
the present disclosure. Such ink vehicles may include a mixture of
a variety of different agents, including, surfactants, solvents,
co-solvents, anti-kogation agents, buffers, biocides, sequestering
agents, viscosity modifiers, surface-active agents, water, etc.
[0064] As used herein, "colorant" can include dyes and/or
pigments.
[0065] As used herein, "dye" refers to compounds or molecules that
absorb electromagnetic radiation or certain wavelengths thereof.
Dyes can impart a visible color to an ink if the dyes absorb
wavelengths in the visible spectrum.
[0066] As used herein, "pigment" generally includes pigment
colorants, magnetic particles, aluminas, silicas, and/or other
ceramics, organo-metallics or other opaque particles, whether or
not such particulates impart color. Thus, though the present
description primarily exemplifies the use of pigment colorants, the
term "pigment" can be used more generally to describe not only
pigment colorants, but other pigments such as organometallics,
ferrites, ceramics, etc. In one specific example, however, the
pigment is a pigment colorant.
[0067] As used herein, "ink-jetting" or "jetting" refers to
compositions that are ejected from jetting architecture, such as
ink-jet architecture. Ink-jet architecture can include thermal or
piezo architecture. Additionally, such architecture can be
configured to print varying drop sizes such as less than 10
picoliters, less than 20 picoliters, less than 30 picoliters, less
than 40 picoliters, less than 50 picoliters, etc.
[0068] As used herein, the term "substantial" or "substantially"
when used in reference to a quantity or amount of a material, or a
specific characteristic thereof, refers to an amount that is
sufficient to provide an effect that the material or characteristic
was intended to provide. The exact degree of deviation allowable
may in some cases depend on the specific context.
[0069] As used herein, the term "about" is used to provide
flexibility to a numerical range endpoint by providing that a given
value may be "a little above" or "a little below" the endpoint. The
degree of flexibility of this term can be dictated by the
particular variable and determined based on the associated
description herein.
[0070] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials may be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on their
presentation in a common group without indications to the
contrary.
[0071] Concentrations, amounts, and other numerical data may be
expressed or presented herein in a range format. It is to be
understood that such a range format is used merely for convenience
and brevity and thus should be interpreted flexibly to include not
only the numerical values explicitly recited as the limits of the
range, but also to include individual numerical values or
sub-ranges encompassed within that range as if each numerical value
and sub-range is explicitly recited. As an illustration, a
numerical range of "about 1 wt % to about 5 wt %" should be
interpreted to include not only the explicitly recited values of
about 1 wt % to about 5 wt %, but also include individual values
and sub-ranges within the indicated range. Thus, included in this
numerical range are individual values such as 2, 3.5, and 4 and
sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same
principle applies to ranges reciting only one numerical value.
Furthermore, such an interpretation should apply regardless of the
breadth of the range or the characteristics being described.
EXAMPLES
[0072] The following illustrates several examples of the present
disclosure. However, it is to be understood that the following are
only illustrative of the application of the principles of the
present disclosure. Numerous modifications and alternative
compositions, methods, and systems may be devised without departing
from the spirit and scope of the present disclosure. The appended
claims are intended to cover such modifications and
arrangements.
Example 1
[0073] Synthesis of 2-hydroxythioxanthen-9-one: 2-Mercaptobenzoic
acid (61.6 g, 0.4 mol) was added to concentrated sulfuric acid (600
mL) and stirred until uniformly dispersed. Then phenol (188.2 g, 2
mol) was added slowly and proportionwise with stirring, maintaining
the temperature below 60.degree. C. After the addition, the mixture
was stirred for 1 hour at room temperature and then for 2 hours at
95-100.degree. C. The reaction mixture was allowed to cool to room
temperature and then carefully poured into 4.5 L of boiling water.
The mixture was stirred and filtered. The filter cake was then
washed with water and dried in vacuum, which was then further
purified by flash chromatography to give the desired
2-hydroxythioxanthen-9-one (3) (60 g, 60% yield).
Example 2
[0074] Synthesis of sodium salt of 2-hydroxythioxanthen-9-one: To a
mixture of 2-hydroxythioxanthen-9-one (28.5 g, 0.125 mol) in 300 mL
of THF was added sodium hydroxide (30 g, 0.75 mol). The mixture was
heated to reflux for 2 hours. After cooling down to room
temperature, THF was evaporated off. Then to the flask was added
200 mL of water and the solid was separated by filtration, washed
with acetone (2.times.100 ml) and then hexanes (2.times.100 ml) and
finally dried in an oven overnight, producing the desired sodium
salt of 2-hydroxythioxanthen-9-one (28 g, 90% yield).
Example 3
[0075] Synthesis of dichloro-polyethylene glycol-1000: A mixture of
polyethylene glycol-1000 (100 grams, 0.1 mol), thionyl chloride (60
grams, 0.5 mol) and 0.1 grams of N-dimethylformamide (DMF) was
heated to reflux for 5 hours. After cooling down to room
temperature, 20 mL of methanol was added slowly to the solution and
stirred for 1 hour. Then the methanol and unreacted thionyl
chloride were removed by vacuum to give the desired
dichloro-polyethylene glycol (100 grams, 97% yield).
Example 4
[0076] Synthesis of dichloro-polyethylene glycol-600: A mixture of
polyethylene glycol-600 (100 grams, 0.1 mol), thionyl chloride (60
grams, 0.5 mol) and 0.1 grams of N-dimethylformamide (DMF) was
heated to reflux for 5 hours. After cooling down to room
temperature, 20 mL of methanol was added slowly to the solution and
stirred for 1 hour. Then the methanol and unreacted thionyl
chloride were removed by vacuum to give the desired
dichloro-polyethylene glycol (102 grams, 96% yield).
Example 5
[0077] Synthesis of polyethylene glycol di-tosylate: To a solution
of polyethylene glycol-1000 (100 grams, 0.1 mol) in 250 mL of
dichloromethane was added pyridine (14 mL, 0.16 mol). The above
solution was cooled to 0.degree. C. and then p-toluenesulfonyl
chloride (22.88 grams, 0.12 mol) was added portion-wise at
0.degree. C. under N.sub.2. The resulting solution was poured into
ice-water. The organic layer was separated, and the aqueous layer
was extracted with chloroform (2.times.50 ml). The combined organic
layer was washed with water and dried over sodium sulfate. The
sodium sulfate was filtered off and evaporation of solvent gave the
desired polyethylene glycol di-tosylate (65 grams, 100% yield).
Example 6
[0078] Synthesis of chloro mono-methyl polyethylene glycol ether: A
mixture of mono-methyl polyethylene glycol ether (100 grams, 0.18
mol), thionyl chloride (60 grams, 0.5 mol) and 0.1 grams of
N-dimethylformamide (DMF) was heated to reflux for 5 hours. After
cooling down to room temperature, 20 mL of methanol was added
slowly to the solution and stirred for 1 hour. Then the methanol
and unreacted thionyl chloride were removed by vacuum to give the
desired chloro mono-methyl polyethylene glycol ether (14) (100
grams, 97% yield).
Example 7
[0079] Synthesis of bis(2-oxythioxanthone) derivative of PEG 1000:
A mixture of sodium salt of 2-hydroxythioxanthone (28 g, 0.112 mol)
and dichloro-polyethylene glycol -1000 (58 g, 0.056 mol) in 100 mL
of DMF was heated to reflux for 2 hours. Then DMF was removed by
distillation. After cooling down to room temperature, to the
residue was added 500 mL of acetone and 10 grams of activated
carbon. The mixture was then heated to reflux for 20 min. Then the
solid was filtered off by simple filtration. Evaporation of solvent
by rotary evaporator gave a residue, which was further purified by
flash chromatography, giving rise to the desired
bis(2-oxythioxanthone) derivative of PEG 1000 (60 g, 75%
yield).
Example 8
[0080] Synthesis of bis(2-oxythioxanthone) derivative of PEG 600: A
mixture of sodium salt of 2-hydroxythioxanthone (34.7 g, 0.125 mol)
and dichloro-polyethylene glycol -600 (40 g, 0.0625 mol) in 100 mL
of DMF was heated to reflux for 2 hours. Then DMF was removed by
distillation. After cooling down to room temperature, to the
residue was added 500 mL of acetone and 10 grams of activated
carbon. The mixture was then heated to reflux for 20 min. Then the
solid was filtered off by simple filtration. Evaporation of solvent
by rotary evaporator gave a residue, which was further purified by
flash chromatography, giving rise to the desired
bis(2-oxythioxanthone) derivative of PEG 600 (35 g, 55% yield).
Example 9
[0081] Synthesis of bis(2-oxythioxanthone) derivative of PEG 550: A
mixture of sodium salt of 2-hydroxythioxanthone (34.7 g, 0.125 mol)
and chloro mono-methyl polyethylene glycol ether (71 g, 0.125 mol)
in 100 mL of DMF was heated to reflux for 2 hours. Then DMF was
removed by distillation. After cooling down to room temperature, to
the residue was added 500 mL of acetone and 10 grams of activated
carbon. The mixture was then heated to reflux for 20 min. Then the
solid was filtered off by simple filtration. Evaporation of solvent
by rotary evaporator gave a residue, which was further purified by
flash chromatography, giving rise to the desired
bis(2-oxythioxanthone) derivative of PEG 550.
Example 10
[0082] A photo curable inkjet ink (UV LED curable) is prepared by
mixing the following components as shown in Table 2.
TABLE-US-00002 TABLE 2 Component Weight Percent Photo reactive
binder (UV reactive) 15% Irgacure .RTM. 819 (co-photo initiator)
0.3% bis(2-oxythioxanthone) derivative of 0.5% PEG 600 (type II
photo initiator or sensitizer) LEG-1 (surfactant) 1% CT-211
(surfactant) 1% Crodafos .RTM. N3 (anti-kogation agent) 0.5%
Pigments 2.5% 2-hydroxyethyl-2-pyrrolidone 10% (co-solvent) Water
69.2%
Example 11
[0083] A UV or LED curable inkjet ink is prepared by mixing the
following components as shown in Table 3.
TABLE-US-00003 TABLE 3 Component Weight Percent Photo reactive
binder (UV reactive) 5% Irgacure .RTM. 819 (photo initiator) 0.1%
bis(2-oxythioxanthone) derivative of 0.25% PEG 600 (type II photo
initiator or sensitizer) Aniline derivative of Jeffamine .RTM. 900
0.5% (amine synergist) LEG-1 (surfactant) 1% CT-211(surfactant)
0.5% Crodafos .RTM. N3 (anti-kogation agent) 0.5% Pigments 3%
2-hydroxyethyl-2-pyrrolidone 10% (co-solvent) Water 79.15%
Example 12
[0084] A UV or LED curable inkjet ink is prepared by mixing the
following components as shown in Table 4.
TABLE-US-00004 TABLE 4 Component Weight Percent Photo reactive
binder (UV reactive) 10% Irgacure .RTM. 819 (co-photo initiator)
0.2% bis(2-oxythioxanthone) derivative of 0.5% PEG 600 (type II
photo initiator or sensitizer) LEG-1 (surfactant) 1% CT-211
(surfactant) 1% Crodafos .RTM. N3 (anti-kogation agent) 0.5%
Pigments 4% 2-hydroxyethyl-2-pyrrolidone 10% (co-solvent) Water
72.5%
Example 13
[0085] A photo curable inkjet ink (UV LED curable) is prepared by
mixing the following components as shown in Table 5.
TABLE-US-00005 TABLE 5 Component Weight Percent Photo reactive
binder (UV reactive) 15% Irgacure .RTM. 819 (co-photo initiator)
0.3% bis(2-oxythioxanthone) derivative of 1% PEG 600 (type II photo
initiator or sensitizer) LEG-1 (surfactant) 1% CT-211 (surfactant)
1% Crodafos .RTM. N3 (anti-kogation agent) 0.5% Pigments 2.5%
2-hydroxyethyl-2-pyrrolidone 10% (co-solvent) Water 68.7%
Example 14
[0086] A photo curable inkjet ink (UV LED curable) is prepared by
mixing the following components as shown in Table 6.
TABLE-US-00006 TABLE 6 Component Weight Percent Photo reactive
binder (UV reactive) 15% Irgacure .RTM. 819 (co-photo initiator)
0.3% bis(2-oxythioxanthone) derivative of 3% PEG 600 (type II photo
initiator or sensitizer) LEG-1 (surfactant) 1% CT-211 (surfactant)
1% Crodafos .RTM. N3 (anti-kogation agent) 0.5% Pigments 2.5%
2-hydroxyethyl-2-pyrrolidone 10% (co-solvent) Water 66.7%
Example 15
[0087] A photo curable inkjet ink (UV LED curable) is prepared by
mixing the following components as shown in Table 7.
TABLE-US-00007 TABLE 7 Component Weight Percent Photo reactive
binder (UV reactive) 15% Irgacure .RTM. 819 (co-photo initiator)
0.3% bis(2-oxythioxanthone) derivative of 5% PEG 600 (type II photo
initiator or sensitizer) LEG-1 (surfactant) 1% CT-211 (surfactant)
1% Crodafos .RTM. N3 (anti-kogation agent) 0.5% Pigments 2.5%
2-hydroxyethyl-2-pyrrolidone 10% (co-solvent) Water 64.7%
Example 16
[0088] A photo (UV LED) curable inkjet ink was prepared with the
ingredients and proportions as in Example 10, using the following
method: (1) Mix UV-curable polyurethane dispersion, 30% of the
water amount and IRG819 PI dispersion at 60.degree. C. for 5 min;
(2) Mix 2HE2P, 70% of the water amount, Crodafos N3A, CT211, and
LEG-1, then neutralize to pH=7.5 with KOH solution; (3) Combine the
mixtures from steps (1) and (2); (4) Add bis(2-oxythioxanthone)
derivative of PEG 600 (type II photo initiator or sensitizer), mix
well until it is dissolved into the mixture; (5) Mix (4) Into
14-SE-73 pigment dispersion; and (6) Adjust to pH=8.5 using KOH
solution.
Example 17
[0089] A print test of the ink from Example 16 was performed using
the following method: (1) Ink was filled into TIJ4 pen; (2) Fixer
was printed from a different pen onto two paper substrates: offset
coated paper (Sterling Ultra Gloss "SUG") and whitetop coated Kraft
liner RockTenn 1 ("RT1"); (3) Ink was printed onto the paper
substrates; (4) Ink was immediately dried using hot air blower for
5 seconds at 375.degree. F.; and (5) Dried ink was then immediately
cured at a speed of 100 fpm using a 16 W/cm.sup.2 LED 395 nm
wavelength (from Phoseon).
Example 18
[0090] Durability tests were performed on the printed ink from
Example 17. A wet rub test was performed after a pre-defined time
period after printing and curing. For SUG, the wet rub test was
performed 24 hr after printing. For RT1, the test was preformed 72
hrs after printing. A Taber test tool was used with Crockmeier
cloth attached to the tip. The weight load was 350 g. One cycle was
performed for SUG, and two cycles for RT1. Windex.RTM. solution was
used during the wet rub test. The delta optical density (.DELTA.OD)
was determined by measuring OD before and after the rub. The lower
the .DELTA.OD, the better the durability. A .DELTA.OD<0.15 is
considered a very good score. An immediate dry rub test was also
performed. In this test, a hand held rubbing tool was used to
assess the smearing of dried and cured ink immediately after
printing. The tool was fit with a rubber tip that when pushed down
applies a constant pressure of 6-7 lb. The .DELTA.OD is measured
before and after the rub. The lower the .DELTA.OD, the better the
durability. A .DELTA.OD<0.15 is considered a very good score.
The results of the tests were as follows: The Example 10 black ink
was printed as described above in two methods: Test 1--with the
curing step; Test 2--without the curing step. The durability was
tested on both papers SUG and RT1, using both durability methods
described above, namely, Wet Rub and Immediate Rub. The results are
shown in Table 8:
TABLE-US-00008 TABLE 8 Test 1-with Curing Test 2-without Curing
.DELTA.OD .DELTA.OD Example 10 Black Ink Wet Immediate Wet
Immediate on Media Rub Dry Rub Rub Dry Rub SUG 0.23 0.14 1.73 0.71
RT1 0.13 0.06 1.24 0.5
[0091] The results show that the Example 10 Black ink had
significantly better wet rub and immediate dry rub resistance after
curing. Initial OD was 2.08 and 1.76 on SUG and RT1 therefore a
.DELTA.OD of 0.23 for example means that after rubbing the print
lost 0.23 OD units out of the initial 2.08 OD measuring, a
.DELTA.OD of 1.73 means that that ink lost a significant amount of
1.73 OD units out of the initial 2.08 OD measurement. The
durability improvement by curing is evident in both Wet Rub and
Immediate Rub measurements suggesting that the photo-initiator and
bis(2-oxythioxanthone) derivative of PEG 600 (type II photo
initiator or sensitizer) sensitizer package are efficiently curing
and crosslinking the ink.
[0092] While the present technology has been described with
reference to certain examples, those skilled in the art will
appreciate that various modifications, changes, omissions, and
substitutions can be made without departing from the spirit of the
disclosure. It is intended, therefore, that the disclosure be
limited only by the scope of the following claims.
* * * * *