U.S. patent application number 11/503308 was filed with the patent office on 2007-02-15 for cationic ink formulations.
Invention is credited to James M. Jang.
Application Number | 20070035601 11/503308 |
Document ID | / |
Family ID | 37757892 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070035601 |
Kind Code |
A1 |
Jang; James M. |
February 15, 2007 |
Cationic ink formulations
Abstract
A printing method includes jetting a curable ink including at
least one of an oxetane compound, a siloxane compound, or a sulfide
compound onto a substrate.
Inventors: |
Jang; James M.; (Keene,
NH) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
37757892 |
Appl. No.: |
11/503308 |
Filed: |
August 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60707898 |
Aug 12, 2005 |
|
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|
Current U.S.
Class: |
347/100 |
Current CPC
Class: |
B41M 5/007 20130101;
B41J 11/00212 20210101; C09D 11/101 20130101; C09D 11/30 20130101;
H05K 2203/013 20130101; C08G 59/3254 20130101; B41M 7/0081
20130101; G03F 7/038 20130101; H05K 2203/161 20130101; B41J
11/00214 20210101; B41M 5/0023 20130101; C08G 65/18 20130101; G03F
7/0755 20130101; H05K 1/0266 20130101; B41J 11/002 20130101; H05K
2203/122 20130101; B41M 5/0047 20130101 |
Class at
Publication: |
347/100 |
International
Class: |
G01D 11/00 20060101
G01D011/00 |
Claims
1. A method, comprising: jetting ink onto a substrate to provide a
mark, the ink comprising a cationic reagent having at least one
siloxane group, a photoinitiating system, and a colorant; and
curing the ink by exposing the mark to light.
2. The method of claim 1, wherein the cationic reagent is a
siloxane epoxide.
3. The method of claim 2, wherein the ink further comprises an
oxetane compound.
4. The method of claim 3, wherein the oxetane compound has multiple
oxetane rings.
5. The method of claim 4, wherein the oxetane compound comprises at
least one of 3,3'-oxybis(methylene)bis(3-ethyloxetane),
1,4-bis(((3-ethyloxetan-3-yl)methoxy)methyl)benzene, or
3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane.
6. The method of claim 3, wherein the oxetane compound has a
viscosity of at least about 25 centipoises at 25.degree. C.
7. The method of claim 3, wherein the oxetane compound has a flash
point of more than 115.degree. C.
8. The method of claim 3, wherein the oxetane compound has a
boiling point of greater than about 90.degree. C. at a pressure of
1 atmosphere.
9. The method of claim 3, wherein the oxetane compound has a
molecular weight of more than about 130 grams per mole.
10. The method of claim 3, wherein the ink comprises at least about
20% by weight of oxetane compound and at least about 20% by weight
of the siloxane epoxide compound.
11. The method of claim 2, wherein the ink further comprises at
least one of a cylcoaliphatic epoxide compound or a glycidyl ether
epoxide compound.
12. The method of claim 2, wherein the siloxane epoxide compound
comprises multiple siloxane groups.
13. The method of claim 12, wherein the siloxane epoxide compound
comprises PC1000, PC2003, a derivative of PC1000, a derivative of
PC2003, or a combination thereof.
14. The method of claim 2, wherein the ink further comprises a
sulfur compound.
15. The method of claim 14, wherein the sulfur compound is a
sulfide compound and the amount of sulfide compound in the ink is
at least about 0.1% by weight and is about 2% or less by weight of
the ink.
16. The method of claim 15, wherein the sulfide compound comprises
a diphenyl sulfide compound or a di-alkyl sulfide compound.
17. The method of claim 2, wherein the ink further comprises an
alcohol or a polyol.
18. The method of claim 2, wherein the photoinitiating system
comprises an initiator and a sensitizer.
19. The method of claim 18, wherein the sensitizer comprises a
polycyclic aromatic compound.
20. The method of claim 2, wherein the ink has an ASTM 3363 pencil
hardness test value of at least about 4H on a glass substrate.
21. The method of claim 2, wherein the substrate comprises glass or
a printed circuit board.
22. The method of claim 2, comprising waiting for at least two
seconds after the jetting the ink before initiating the curing of
the ink.
23. The method of claim 2, wherein the step of jetting the ink
comprises jetting the ink onto each of multiple substrates to
provide a mark on each of the substrates and the step of curing the
ink comprises curing the ink on each of the substrates by exposing
the marks to ultraviolet light after jetting the ink onto the
multiple substrates.
24. A composition, comprising: a first cationic reagent; a second
cationic reagent having at least one siloxane group, the second
cationic reagent being different from the first cationic reagent; a
photoinitiating system; and a colorant, wherein the composition has
a viscosity of about 50 centipoises or less.
25. The composition of claim 24, wherein the viscosity is about 35
centipoises or less.
26. An inkjet printer nozzle comprising the composition of claim
24.
27. The composition of claim 24, wherein the second cationic
reagent is a siloxane epoxide.
28. An inkjet printer cartridge, comprising: a reservoir comprising
a composition comprising: a cationic reagent having at least one
siloxane group; a photoinitiating system; and a colorant.
29. The inkjet printer cartridge of claim 28, wherein the cationic
reagent is a first cationic reagent and the ink composition further
comprises a second cationic reagent different from the first
cationic reagent.
30. The composition of claim 28, wherein the cationic reagent is a
siloxane epoxide.
Description
CLAIM OF PRIORITY
[0001] This application claims priority under 35 USC .sctn. 119(e)
to U.S. Patent Application Ser. No. 60/707,898, filed on Aug. 12,
2005, the entire contents of which are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to inks.
BACKGROUND
[0003] During inkjet printing, ink is ejected, generally at
elevated temperature, from a component of an inkjet printer (e.g.,
from one or more nozzles of a print head) onto a substrate. In some
instances, the ejecting is followed by a curing step. One method of
curing involves exposing to ultraviolet (UV) radiation an ink that
contains reactive reagents that polymerize upon exposure to UV
radiation. Typically, the ink is exposed to UV radiation within
milliseconds of printing on the substrate. The rapid exposure to UV
radiation controls dot gain and is known as pinning.
[0004] Examples of inkjet printing are described in U.S. Ser. No.
11/058,777, filed Feb. 16, 2005, published as US 20050195265, and
U.S. provisional application no. 60/549,645, filed Mar. 3, 2004,
both of which are incorporated by reference herein in their
entirety.
SUMMARY
[0005] The invention relates to inks.
[0006] One aspect of the invention relates to an ink including at
least one oxetane compound. The oxetane compound has one or more
(e.g., multiple) oxetane groups.
[0007] In some embodiments, a method includes jetting ink onto a
substrate to provide a mark. The ink includes an oxetane compound
and a photoinitiating system. The ink may include a colorant. The
ink may be cured by exposing the mark to light (e.g., visible
light, ultraviolet radiation having a wavelength of less than about
400 nanometers, or a combination thereof).
[0008] In some embodiments, the oxetane compound has a viscosity of
at least about 25 centipoises at a temperature of 25.degree. C.
[0009] In some embodiments, the oxetane compound has a flash point
(open cup) of more than 115.degree. C.
[0010] In some embodiments, the oxetane compound has a boiling
point of greater than about 110.degree. C. at a pressure of 5 mm
Hg.
[0011] In some embodiments, the oxetane compound has a molecular
weight of more than about 130 grams per mole.
[0012] In some embodiments, the oxetane compound includes at least
one of 3,3'-oxybis(methylene)bis(3-ethyloxetane),
1,4-bis(((3-ethyloxetan-3-yl)methoxy)methyl)benzene, or
3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane.
[0013] The ink may further include an epoxide compound (e.g., at
least one of a siloxane epoxide compound, a cylcoaliphatic epoxide
compound, or a glycidyl ether epoxide compound).
[0014] In some embodiments, the ink includes at least about 20% by
weight of oxetane compound and at least about 20% by weight of the
epoxide compound.
[0015] The ink may include at least one of an alcohol, a polyol, or
an ester.
[0016] In some embodiments, the ink further comprises a sulfur
compound (e.g., a sulfide compound). The ink may include at least
about 0.1% by weight of the sulfide compound. The amount of sulfide
compound may be about 2% or less by weight of the ink.
[0017] The sulfide compound may be a diphenyl sulfide compound, a
di-alkyl sulfide compound, or a combination thereof
[0018] In some embodiments, the ink jetted onto the substrate to
provide the mark has an ASTM 3363 pencil hardness test value of at
least about 4H on a glass substrate.
[0019] The substrate may be, for example, a glass substrate or a
printed circuit board.
[0020] The photoinitiating system may include an initiator and a
sensitizer (e.g., a polycyclic aromatic compound).
[0021] In some embodiments, the method includes waiting for at
least two seconds after the jetting the ink before initiating the
curing of the ink.
[0022] In some embodiments, the step of jetting the ink includes
jetting the ink onto each of multiple substrates to provide a mark
on each of the substrates and the step of curing the ink includes
curing the ink on each of the substrates by exposing the marks to
light after jetting the ink onto the multiple substrates.
[0023] In some embodiments, the invention relates to a composition
including a cationic reagent, an oxetane compound different from
the cationic reagent and having multiple oxetane rings, a
photoinitiating system, and a colorant. The composition has a
viscosity of about 50 centipoises or less (e.g., about 35
centipoise or less).
[0024] In some embodiments, the composition is present in an inkjet
printer nozzle.
[0025] In some embodiments, the invention relates to an inkjet
printer cartridge including a reservoir including a composition
that includes an oxetane compound having multiple oxetane rings, a
photoinitiating system, and a colorant. The ink composition may
further include a cationic reagent different from the oxetane
compound.
[0026] In some embodiments, the invention relates to a method that
includes jetting ink onto a substrate to provide a mark. The ink
includes an oxetane compound having a viscosity of least about 25
centipoises at 25.degree. C., a photoinitiating system, and a
colorant. The ink is cured by exposing the mark to light.
[0027] In some embodiments, the invention relates to a method that
includes jetting ink onto a substrate to provide a mark, the ink
includes an oxetane compound having an open cup flash point of more
than 115.degree. C., a photoinitiating system, and a colorant. The
ink is cured by exposing the mark to light.
[0028] In some embodiments, the invention relates to a method that
includes jetting ink onto a substrate to provide a mark. The ink
includes an oxetane compound having a boiling point of more than
about 90.degree. C. at a pressure of 1 atmosphere, a
photoinitiating system, and a colorant. The ink is cured by
exposing the mark to light.
[0029] In some embodiments, the invention relates to a method that
includes jetting ink onto a substrate to provide a mark. The ink
includes an oxetane compound having a molecular weight of more than
about 130 grams per mole, a photoinitiating system, and a colorant.
The ink is cured by exposing the mark to light.
[0030] Another aspect of the invention relates to an ink including
at least one siloxane compound.
[0031] In some embodiments, a method includes jetting ink onto a
substrate to provide a mark. The ink includes a cationic reagent
having at least one siloxane group and a photoinitiating system.
The ink may include a colorant. The ink may be cured by exposure to
light (e.g., visible light, ultraviolet radiation having a
wavelength of less than about 400 nanometers, or a combination
thereof).
[0032] The cationic reagent may be a siloxane epoxide.
[0033] The ink may further include an oxetane compound (e.g., an
oxetane compound with multiple oxetane rings). The oxetane compound
may include, for example, at least one of
3,3'-oxybis(methylene)bis(3-ethyloxetane),
1,4-bis(((3-ethyloxetan-3-yl)methoxy)methyl)benzene, or
3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane.
[0034] In some embodiments, the oxetane compound has a viscosity of
at least about 25 centipoises at a temperature of 25.degree. C.
[0035] In some embodiments, the oxetane compound has a flash point
(open cup) of more than 115.degree. C.
[0036] In some embodiments, the oxetane compound has a boiling
point of greater than about 110.degree. C. at a pressure of 5 mm
Hg.
[0037] In some embodiments, the oxetane compound has a molecular
weight of more than about 130 grams per mole.
[0038] In some embodiments, the ink includes at least about 20% by
weight of the oxetane compound and at least about 20% by weight of
the siloxane epoxide compound.
[0039] The ink may further include at least one of a cylcoaliphatic
epoxide compound or a glycidyl ether epoxide compound.
[0040] The siloxane compound may include multiple siloxane
groups.
[0041] The siloxane compound may include, as defined below, PC1000,
PC2003, a derivative of PC1000, a derivative of PC2003, or a
combination thereof.
[0042] In some embodiments, the ink further comprises a sulfur
compound (e.g., a sulfide compound). The ink may include at least
about 0.1% by weight of the sulfide compound. The amount of sulfide
compound may be about 2% or less by weight of the ink.
[0043] The sulfide compound may be a diphenyl sulfide compound, a
di-alkyl sulfide compound, or a combination thereof.
[0044] In some embodiments, the ink jetted onto the substrate to
provide the mark has an ASTM 3363 pencil hardness test value of at
least about 4H on a glass substrate.
[0045] The substrate may be, for example, a glass substrate or a
printed circuit board.
[0046] The photoinitiating system may include an initiator and a
sensitizer (e.g., a polycyclic aromatic compound).
[0047] In some embodiments, the method includes waiting for at
least two seconds after the jetting the ink before initiating the
curing of the ink.
[0048] In some embodiments, the step of jetting the ink includes
jetting the ink onto each of multiple substrates to provide a mark
on each of the substrates and the step of curing the ink includes
curing the ink on each of the substrates by exposing the marks to
light after jetting the ink onto the multiple substrates.
[0049] Another aspect of the invention relates to a composition
that includes a first cationic reagent, a second cationic reagent
having at least one siloxane group and a photoinitiating system.
The second cationic reagent is different from the first cationic
reagent. The composition may include a colorant. The composition
has a viscosity of about 50 centipoises or less (e.g., about 35
centipoises or less).
[0050] The composition may be present in an inkjet printer
nozzle.
[0051] The second cationic reagent may be a siloxane epoxide.
[0052] Another aspect of the invention relates to an inkjet printer
cartridge that includes a reservoir including a composition that
includes a cationic reagent having at least one siloxane group, a
photoinitiating system, and a colorant.
[0053] The cationic reagent may be a siloxane epoxide.
[0054] The cationic reagent may be a first cationic reagent and the
ink composition may further include a second cationic reagent
different from the first cationic reagent.
[0055] Another aspect of the invention relates to an ink including
at least one inhibitor. The inhibitor may be a sulfide
compound.
[0056] In some embodiments, a method includes jetting an ink that
includes a sulfide compound onto a substrate. The ink may also
include at least one of a cationic reagent, a photoinitiating
system, a sulfide compound, and a colorant. The ink may be cured by
exposing the mark to light (e.g., visible light, ultraviolet
radiation having a wavelength of less than about 400 nanometers, or
a combination thereof).
[0057] The sulfide compound may include at least one of a diphenyl
sulfide compound or a di-alkyl sulfide compound.
[0058] The cationic reagent may include an epoxide compound (e.g.,
an epoxide compound that has multiple expoxy rings).
[0059] The substrate may be, for example, a glass substrate or a
printed circuit board.
[0060] The cationic reagent may include at least one of a siloxane
epoxide compound, a cylcoaliphatic epoxide compound, or a glycidyl
ether epoxide compound.
[0061] The ink can include at least about 20% by weight of oxetane
compound and at least about 20% by weight of the epoxide
compound.
[0062] In some embodiments of the invention, a composition includes
a cationic reagent, a photoinitiating system, a sulfide compound,
and a colorant. The composition may have a viscosity of about 50
centipoises or less (e.g., about 35 centipoises or less).
[0063] In some embodiments, the composition is present in an inkjet
printer nozzle.
[0064] In some embodiments, the viscosity of the composition
determined at temperature of about 68.degree. C. increases by about
10% or less (e.g., about 7.5% or less, about 5% or less) after
storage of the ink at 70.degree. in the dark for at least 7 days
(e.g., 14 days, 21 days, or 30 days).
[0065] In some embodiments, the invention relates to an inkjet
printer cartridge that includes a reservoir that includes a
composition that includes a cationic reagent, a photoinitiating
system, a sulfide compound, and a colorant.
[0066] Another aspect of the invention relates to a method of
printing an ink described herein.
[0067] Another aspect of the invention relates to a substrate
(e.g., a glass substrate or a printed circuit board) having one or
marks formed of an ink described herein.
[0068] Another aspect of the invention relates to an ink reservoir
(e.g., an ink cartridge for an inkjet printer) including an ink
described herein.
[0069] Other features, objects, and advantages of the invention
will be apparent from the description and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0070] FIGS. 1A-1C illustrate a printing assembly of an inkjet
printer.
DETAILED DESCRIPTION
[0071] An ink includes one or more cationic reagents (e.g., at
least one oxetane compound, at least one siloxane compound, or
combination thereof) and, typically, a photoinitiating system. The
ink can be jetted onto a substrate using an inkjet printer (e.g.,
from one or more nozzles of a print head of an inkjet printer) to
provide a mark. The ink of the mark is cured by exposing the mark
to light (e.g., visible light, ultraviolet radiation having a
wavelength of less than about 400 nanometers, or a combination
thereof). A component of the photoinitiating system (e.g., a
photoinitiator) absorbs the light and initiates polymerization of
the one or more cationic reagents of the ink. The polymerization
typically cures the mark.
[0072] The cationic reagents contribute to desirable properties of
the ink prior to curing (e.g., viscosity, vapor pressure, or
boiling point) while providing a cured mark with desired properties
(e.g., hardness, flexibility). For example, a cationic reagent (or
a combination of cationic reagents) may have a viscosity at
printing temperature that permits the ink to be jetted but a vapor
pressure sufficiently low to reduce (e.g., prevent) evaporation of
the reagent during storage and handling. The cured mark may have a
hardness that resists damage (e.g., upon impact or abrasion) yet is
flexible enough to resist cracking.
[0073] An ink may include an inhibitor that reduces (e.g.,
prevents) polymerization of the ink in the absence of light. The
inhibitor can contribute to storage and handling properties of the
ink by reducing (e.g., preventing) a tendency of the viscosity of
the ink to increase before being jetted and cured by light
exposure.
[0074] The ink may also include at least one other component such
as a colorant or a Theological modifying additive.
[0075] Inks and related systems and methods are discussed
below.
[0076] Cationic Reagents
[0077] A cationic reagent typically includes at least one cyclic
ether group (e.g., one or more epoxide groups (e.g., a three-member
cyclic ether), one or more oxetane groups (e.g., a four member
cyclic ether), or a combination of such groups). Polymerization of
the cationic reagent typically includes a ring-opening reaction of
the cyclic ether group(s) of the reagent (e.g., cationic ring
opening polymerization). The polymerization can be initiated by,
for example, an initiating species (e.g., a cation) formed by a
photoinitiator upon absorption of light by the photoinitiator.
[0078] The cationic reagent can be a monomer or an oligomer (e.g.,
a compound having multiple repeat units, at least some of which
(e.g., most or all) typically have at least one cyclic ether
group).
[0079] In some embodiments, the cationic reagent is an oxetane
compound having at least one oxetane group (e.g., at least two
oxetane groups or more). An ink may include a combination of such
oxetane compounds.
[0080] The oxetane compound may have chemical and/or physical
properties as desired.
[0081] In some embodiments, a viscosity of the oxetane compound is
at least about 25 centipoises (e.g., at least about 30 centipoises,
at least about 50 centipoises, at least about 75 centipoises) at a
temperature of 25.degree. C. Unless specified otherwise, all
viscosities referred to herein are measured using a Brookfield
DV-II viscometer, a SC418 spindle, a Brookfield Thermosel for
temperature control, generally operated at a 60, 30, or 12 RPM
spindle speed, which is dependent on the viscosity of the sample
being tested.
[0082] In some embodiments, a flash point of the oxetane compound
is at least about 115.degree. C. (e.g., at least about 125.degree.
C., at least about 140.degree. C., at least about 180.degree. C.).
Flash points described herein are open cup flash points determined
according to appropriate ASTM protocol.
[0083] In some embodiments, a boiling point of the oxetane compound
is at least about 110.degree. C. (e.g., at least about 115.degree.
C., at least about 117.5.degree. C., at least about 120.degree. C.)
at a pressure of 5 mm Hg.
[0084] In some embodiments, a molecular weight of the oxetane
compound is at least about 130 grams per mole (e.g., at least about
140 grams per mole, at least about 150 grams per mole). The
molecular weight of the oxetane compound is typically about 500
grams per mole or less (e.g., about 300 grams per mole or
less).
[0085] In some embodiments, the oxetane compound includes a carbon
chain (e.g., a linear or branched carbon chain) having a length of
at least 5 carbon atoms (e.g., at least 6 carbon atoms).
[0086] The oxetane compound may include at least two oxetane groups
connected by, for example, a linear ether group of the oxetane
compound.
[0087] In some embodiments, the oxetane compound includes at least
one aromatic group (e.g., at least one phenyl group or derivative
thereof).
[0088] Examples of oxetane compounds include
3,3'-oxybis(methylene)bis(3-ethyloxetane),
1,4-bis(((3-ethyloxetan-3-yl)methoxy)methyl)benzene, and
3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane.
[0089] In some embodiments, the cationic reagent is a siloxane
compound that includes at least one siloxane group (e.g., at least
two siloxane groups, at least three siloxane groups, or more). For
example, the cationic reagent may be a siloxane epoxide (e.g., a
siloxane compound including at least one siloxane group and at
least one epoxide group). An ink may include a combination of
cationic reagents each having at least one siloxane group.
[0090] The siloxane compound may have chemical and/or physical
properties as desired.
[0091] In some embodiments, the cationic reagent includes one or
more siloxane groups to the exclusion of linear ether groups. Such
reagents are free of linear ether groups.
[0092] Examples of siloxane compounds that include at least one
epoxide group include disiloxane compounds (e.g.,
(bis-1,3-[2-(3{7-oxa-bicyclo[4,1,0]heptyl})ethyl]-1,1,3,3-tetramethyl
disiloxane) (PC1000) and epoxide oligomers having a number n
epoxide groups where n is at least 2 (e.g., at least 3, at least 4,
at least 5, at least 6, at least 7). An exemplary oligomer (PC2003)
has the structure: ##STR1## where n is between 2 and 10. In some
embodiments, the cationic reagent may be free of silicon and
include at least one epoxide group (e.g., at least two epoxide
groups or more). An ink can include a combination of such cationic
reagents having at least one epoxide group.
[0093] Exemplary siloxane compounds can be obtained from POLYSET
company, Mechanicville, N.Y.
[0094] The cationic reagent including the at least one epoxide
group compound may have chemical and/or physical properties as
desired.
[0095] In some embodiments, the cationic reagent including the at
least one epoxide group has a molecular weight of at least about
125 grams per mole (e.g., at least about 135 grams per mole). In
some embodiments, the molecular weight of the cationic reagent is
about 500 grams per mole or less (e.g., about 450 grams per mole or
less).
[0096] The cationic reagent including the at least one epoxide
group typically has a viscosity of at least about 1.1 centipoises
at a temperature of 25.degree. C. The cationic reagent generally
has a viscosity of about 20,000 centipoises or less at a
temperature of 25.degree. C.
[0097] Examples of cationic reagents including at least one epoxide
group include cycloaliphatic epoxy compounds such as bis-(3,4-
epoxycyclohexyl)adipate,
3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexane carboxylate, and
7-Oxa-bicyclo[4.1.0]heptane-3-carboxylic acid
7-oxa-bicyclo[4.1.0]hept-3-ylmethyl ester; ether derivatives
including diol derivatives such as 1,4-butanediol diglycidylether
and neopentyl glycol diglycidylether; and glycidyl ethers such as
n-butyl glycidyl ether, distilled butyl glycidyl ether,
2-ethylhexyl glycidyl ether, C8-C 10 aliphatic glycidyl ether,
C12-C14 aliphatic glycidyl ether, O-cresyl glycidyl ether,
P-tertiary butyl phenyl glycidyl ether, nonyl phenyl glycidyl
ether, phenyl glycidyl ether, cyclohexanedimethanol diglycidyl
ether, polypropylene glycol diglycidyl ether, poly glycol
diglycidyl ether, dibromo neopentyl glycol diglycidyl ether,
trimethylopropane triglycidyl ether, castor oil triglycidyl ether,
propoxylated glycerin triglycidyl ether, sorbitol polyglycidyl
ether, glycidyl ester of neodecanoic acid, and glycidyl amines such
as epoxidized meta-xylenediamine.
[0098] In some embodiments, the ink includes at least two (e.g., at
least three or more) cationic reagents. For example, the ink can
include at least one oxetane compound in combination with one or
more other cationic reagents (e.g., in combination with at least
one other oxetane compound, at least one cationic reagent having at
least one siloxane group (e.g., a siloxane epoxide), at least one
cationic reagent having at least one epoxide group, or a
combination thereof). Similarly, the ink can include at least one
cationic reagent having at least one siloxane group (e.g., a
siloxane epoxide) in combination with one or more other cationic
reagents.
[0099] The chemical and/or physical properties of the at least two
cationic reagents of the ink may be as desired.
[0100] In some embodiments, the at least two cationic reagents of
the ink have different viscosities. Typically, one of the cationic
reagents has a lower viscosity than the other. For example, one of
the cationic reagents may have a viscosity at 25.degree. C. of
about 50 centipoises or less (e.g., about 35 centipoises or less,
about 19 centipoises or less) while the other cationic reagent has
a viscosity at 25.degree. C. of about 19 centipoises or more (e.g.,
about 35 centipoises or more, about 50 centipoises or more, about
100 centipoises or more). Examples of cationic reagents used as a
lower viscosity cationic reagent include 1,4-butanediol
diglycidylether, neopentyl glycol diglycidylether, and n-Butyl
glycidyl ether available as Erisys GE-5 from CVC Specialty
Chemicals.
[0101] In some embodiments, the cationic reagents have different
molecular weights. Typically, one of the cationic reagents has a
lower molecular weight than the other. For example, one of the
cationic reagents may have a molecular weight of about 350 grams
per mole or less (e.g., about 300 grams per mole or less, about 250
grams per mole or less) while the other cationic reagent has a
molecular weight of at least about 400 grams per mole (e.g., at
least about 750 grams per mole, at least about 1500 grams per mole,
at least about 5000 grams per mole, at least about 10000 grams per
mole).
[0102] A concentration of the cationic reagent(s) in the ink can be
as desired. Typically, the is concentration is selected to provide
the ink with desired properties (e.g., viscosity, hardness,
flexibility, and cure speed). In some embodiments, an ink may
include a total amount of cationic reagents of at least about 40%
by weight (e.g., at least about 60%, at least about 80%, at least
about 90%) of cationic reagent(s). The total amount of cationic
reagent(s) of the ink may be about 98% or less by weight (e.g.,
about 95% or less).
[0103] In embodiments where the ink includes a combination of
cationic reagents, the ink typically includes at least two (e.g.,
at least three) cationic reagents each having a concentration of at
least about 5% by weight of the ink (e.g., at least about 10%, at
least about 15%, at least about 20%). For example, an ink may
include (a) one or more oxetane compounds having a total
concentration of at least about 5% by weight of the ink (e.g., at
least about 10%, at least about 15%, at least about 20%) and (b)
one or more other cationic reagents including at least one epoxide
group (optionally free of silicon) and having a total concentration
of at least about 5% by weight of the ink (e.g., at least about
10%, at least about 15%, at least about 20%). As another example,
an ink may include (a) one or more siloxane compounds (e.g.,
siloxane epoxides) having a total concentration of at least about
5% by weight of the ink (e.g., at least about 10%, at least about
15%, at least about 20%) and (b) one or more other cationic
reagents free of silicon, including at least one epoxide group, and
having a total concentration of at least about 5% by weight of the
ink (e.g., at least about 10%, at least about 15%, at least about
20%).
[0104] Photoinitiating Systems A photoinitiating system includes at
least one photoinitiator capable of absorbing light (e.g.,
ultraviolet light) to provide an initiating species capable of
initiating polymerization of a cationic reagent or combination of
such reagents. For example, a photoinitiator may generate a strong
acid upon absorbing light. The strong acid is an initiating species
that initiates a ring opening reaction of a cyclic ether of a
cationic reagent, which can then react (e.g., polymerize) with the
cyclic ether of another cationic reagent.
[0105] Examples of photoinitiators include arylsulfonium salts
(e.g., UVI 6992 and UVI 6974) such as mixed triarylsulfonoum
hexafluoroantimonate or hexafluorophosphate, iodonium salts (e.g.,
Deuteron UV 2275 available from Deuteron GmbH, Achim Germany;
Rhodorsil 2076 available from Rhodia, Lyon, France; UV9385C
available from General Electric, Waterford, N.Y.;
Bis(t-butylphenyl)iodonium hexafluorophosphate) available from
Hampford Research, Inc. of Stratford, Conn.; and Irgacure 250
available from Ciba Specialty Chemicals Corp. of Basel,
Switzerland), ferrocenium salts, and diazonium salts.
[0106] In some embodiments, the photoinitiating system includes a
sensitizer in combination with the photoinitiator. The sensitizer
absorbs light (e.g., ultraviolet light and/or visible light) and
transfers energy to the photoinitiator, which provides an
initiating species (e.g., a strong acid) capable of initiating
polymerization of a cationic reagent or combination of such
reagents. For a given light flux, the sensitizer can enhance the
rate of photoinitiation. Alternatively or in combination, the
sensitizer can provide a photoinitiator with the ability to
initiate polymerization of cationic reagents upon exposure to
longer wavelength light than in the absence of the sensitizer.
[0107] Sensitizers can be useful in, for example, inks including
particles (e.g., pigment particles such as rutile titania used to
color the ink and/or provide opacity) which can decrease the
penetration depth of ultraviolet light absorbed by the
photoinitiator. Light having a longer wavelength than ultraviolet
(e.g., visible light) can penetrate more deeply through ink
including the colorant particles to provide more uniform curing of
the ink. Sensitizers typically absorb the longer wavelength light
more efficiently than the photoinitiator itself thereby enhancing
curing of the ink.
[0108] The concentration of photoinitiator and the optional
sensitizer of an ink can be selected as desired. In some
embodiments, the ink includes photoinitiator in the amount of at
least about 0.5% by weight (e.g., at least about 1%). The total
amount of photoinitiator of the ink may be about 3% or less by
weight (e.g., about 2% or less). In some embodiments, the ink
includes sensitizer in the amount of at least about 0.01% by weight
(e.g., at least about 0.05%). The total amount of sensitizer of the
ink may be about 0.5% or less by weight (e.g., about 0.1% or
less).
[0109] Exemplary sensitizers include at least one aromatic group
and include compounds such as 9,10-diethoxy anthracene, 2-ethyl-9,
10-dimethoxyanthracene, isopropylthioxanthone, or perylene.
[0110] Inhibitors
[0111] As discussed above, photoinitiator present in an ink can
provide an initiating species (e.g., a strong acid) that
polymerizes cationic reagent. In some cases, the photoinitiator may
provide such a species even in the absence of light (e.g.,
thermally). This "dark" generation of initiating species may
partially polymerize the ink increasing its viscosity over time
(e.g., during storage of the ink over days, weeks, or months at
ambient temperature).
[0112] An inhibitor reduces (e.g., prevents) polymerization that
results from initiating species generated in the dark yet allows
polymerization to occur when the ink is exposed to light. Thus, the
inhibitor may neutralize initiating species produced in the dark to
reduce (e.g., prevent) polymerization from these initiating
species. However, the larger number of initiating species produced
when the ink is exposed to light during curing allows
polymerization to proceed.
[0113] Typically, the viscosity increase of an ink with inhibitor
is less than the viscosity increase of the same ink but without
inhibitor after storage of the inks in the dark for a period of
time. In some embodiments, the viscosity of the ink with inhibitor
as determined at a temperature of about 68.degree. C. increases by
about 10% or less (e.g., about 7.5% or less, about 5% or less)
after storage of the ink at 700 in the dark for at least 7 days
(e.g., 14 days, 21 days or 30 days).
[0114] In some embodiments, the inhibitor is a sulfide compound
including a sulfur atom having 3 substituents R1, R2, and R3. The
inhibitor typically reacts with an oxonium ion to form a sulfonium
ion that has a reduced tendency to propagate the polymerization
reaction.
[0115] Independently, R1, R2, and R3 may be selected to provide the
inhibitor with a desired level of inhibition. In some embodiments,
at least one (e.g., two or three) of R1, R2, and R3 include an
alkyl group (e.g., methyl, ethyl, propyl, butyl, pentyl, octyl,
nonyl, decyl, or other). The alkyl groups may be different. The
alkyl groups may be branched or linear. The alkyl groups may
include at least one heteroatom (e.g., halogen, or oxygen). The
alkyl groups may include at least one double bond.
[0116] In some embodiments, at least one (e.g., two or three) of
R1, R2, and R3 include an aromatic group (e.g., benzyl or phenyl).
The aromatic groups may be different. The aromatic group may be
substituted with, for example, one or more functional groups, one
or more heteroatoms, one or more alkyl groups, or combination
thereof Each substituent may be a phenyl group.
[0117] In some embodiments, at least one of R1, R2, and R3 is
hydrogen.
[0118] In some embodiments, R1 and R2 are aromatic and R3 is
alkyl.
[0119] In some embodiments, the inhibitor is dodecyl sulfide or
diphenyl sulfide.
[0120] In general, as the number of groups R1, R2, and R3 that are
alkyl as compared to aromatic (e.g., phenyl) increases, the
inhibitory capability of the compound increases.
[0121] In some embodiments, the inhibitor includes a ring
substituted with one or more sulfur atoms (e.g., a cycloaliphatic
sulfur group). For example, the inhibitor may be a thiane (e.g.,
1,4-dithiane).
[0122] In some embodiments, the concentration of inhibitor is at
least about 0.1% by weight (e.g., at least about 0.3%, at least
about 0.75%, at least about 1.5%) of the ink. The concentration of
inhibitor is typically about 2% or less by weight (e.g., about 1%
or less, about 0.75% or less, about 0.5% or less) of the ink.
[0123] In some embodiments, a ratio of a weight of photoinitiator
of the ink to a weight of inhibitor is about 30 or less (e.g.,
about 20 or less, about 15 or less, about 10 or less, about 7 or
less). The ratio of the weight of photoinitiator to the weight of
inhibitor is typically at least about 1 (e.g., at least about 2, at
least about 4).
[0124] A combination of different inhibitors may be used. In such
case, the inhibitor weights and the inhibitor ratios with respect
to photoinitiator refer to total weights.
[0125] Colorants
[0126] An ink can include one or more colorants (e.g., one or more
pigments, one or more dyes, or a combination thereof). Colorants
can provide an ink with, for example, a desired color and/or
opacity. Exemplary colors include black, cyan, magenta, yellow,
red, blue, green, brown, or combinations thereof
[0127] The total amount of colorant may be selected as desired.
Typically, the ink includes a total amount of colorant of at least
about 0.5% by weight (e.g., at least about 3%). The total amount of
colorant may be about 30% or less by weight of the ink (e.g., about
20% by weight or less, about 10% by weight or less, about 5% or
less).
[0128] In some embodiments, the colorant is in the form of
particles (e.g., pigment particles). In such embodiments, the
particles are generally sufficiently small to permit free flow of
the ink through an inkjet printing device. The particle sizes are
generally selected to provide good dispersion stability.
[0129] Examples of suitable pigments particles include pigment
blacks 7, carbon black, graphite; and pigment white titanium
dioxide. Additional examples are disclosed in, e.g., U.S. Pat. No.
5,389,133, which is incorporated by reference herein. The pigment
may also have a modifying group on its surface, such as an
oxygen-containing functionality (e.g., a carboxyl or phenol
group).
[0130] White inks can be made using a titania dispersion. The
titania dispersion may include, for example, a blend of titania
particles having a surface area of between about 8 and about 14
meters squared per gram. The primary particles size of the titania
may be between about 190 and 410 nanometers. The titania particles
are preferably dispersed into a concentrate using a combination of
monomer and dispersant as the dispersing aid, which can result, for
example, in about 60% to about 70% by weight titania. However,
other concentrations can also be suitable, for example, a titania
concentration of about 50% by weight.
[0131] Examples of dyes include Orasol Pink 5BLG, Black RLI, Blue
2GLN, Red G, Yellow 2GLN, Blue GN, Blue BLN, Black CN, and Brown CR
(all available from Ciba-Geigy, Inc., Mississauga, Ontario);
Morfast Blue 100, Red 101, Red 104, Yellow 102, Black 101, and
Black 108 (all available from Morton Chemical Company, Ajax,
Ontario); and a mixture thereof. Additional examples include those
disclosed in, e.g., U.S. Pat. No. 5,389,133, which is incorporated
by reference herein.
[0132] Rheological Modifying Additives
[0133] Examples of Theological modifying additives include
additives that can participate during the UV polymerization of the
cationic reagents (e.g., monomers). Using a hydroxy functional
rheological modifier can reduce the amount of unpolymerized
cationic reagent in the ink, potentially improving the final film
properties.
[0134] In some embodiments, the Theological modifier is an ester
(e.g., a straight chain even numbered monoesters having a carbon
chain length of, for example, from C-28 to C-34). In some
embodiments, the majority of the Theological modifiers have a chain
length of about C-32 and the modifier has a melting point of about
48.degree. C. Examples of such compounds include KESTER WAX (e.g.,
Ester Wax: K-48 and K-56, KOSTER KEUNEN, INC.). Kester Wax K-48
(synthetic Spermaceti/Cetyl Esters NF) is cetyl palmitate and
straight chain even numbered monoesters having a carbon chain
length from C-28 to C-34 with the greastest concentration at C-32
(mp.about.48 .degree. C.). K-56 is cetearyl stearate (stearyl
stearate) and mp.about.54-56.degree. C. (also available from
KOSTER).
[0135] Examples of rheological modifying additives include
hydrogenated cator oil, beeswax, and other additives that include
hydroxy containing moieties such as monoalcohols, diols, and
glyceryls. Examples of monoalcohols include stearyl alcohol
(available from Aldrich Chemical, Milwaukee, Wis.) and Unilin 350
(available from Petrolite of Sugar Land, Tex.). Examples of diols
include 1, 12-stearyldiol (available as Speziol 18/2 from Cognis
Corp. USA Cincinnati, Ohio), 1,10-decanediol (available as Speziol
10/2 from Cognis Corp. USA Cincinnati, Ohio), or
di-trimethylolpropane. Examples of glyceryls include tallow
glycerides.
[0136] The amount of Theological modifier can be selected as
desired. In some embodiments, the ink includes at total amount of
Theological modifier of at least about 1% by weight (e.g., at least
about 3%, at least about 20%). The total amount of Theological
modifier of the ink may be about 30% or less by weight (e.g., about
15% or less, e.g., about 7% or less).
[0137] Other examples rheological modifying additives include
compounds such as erucyl stearamide and ethylene glycol
distearate.
[0138] Other Ink Components
[0139] The pigmented jettable ink can also include a polymeric
dispersant. The polymeric dispersant can assist in stabilizing the
pigment in the jettable ink. The dispersant can, for example,
prevent agglomeration of the pigment. The ink can include between
about 1% and 10% by weight dispersant (e.g., between about 3% and
8% by weight dispersant).
[0140] Examples of dispersants include Solsperse 13,650, 13,940,
17,000, 24,000, 32,000, 36,000; Byk 108; Tego Dispers 700; UNIQEMA
5543; and EFKA 5244, 5207, 6750; which are all commercially
available from Avecia; Byk Chemie; Tego Chemie; Zephryn Uniquema;
and EFKA additives, respectively.
[0141] The amount of dispersant required is generally based on the
amount of pigment in the ink (e.g., the surface area of pigment
particles in grams per meter squared). The dispersant used
typically depends on ink composition including, for example,
properties of the cationic reagent and/or pigment. The selected
dispersant can be soluble in the vehicle, can lack volatility at an
elevated temperature (e.g., 120.degree. C.), and can have good
affinity for the pigment. The dispersant can also include a
synergist that aids dispersion.
[0142] In addition to or in place of a dispersant, a surfactant
compound can be used. The surfactant compound can serve to alter
the surface tension of the ink, and can be an anionic, cationic,
nonionic or amphoteric surfactant compound, such as those described
in McCutcheon's Functional Materials, North American Edition,
Manufacturing Confectioner Publishing Co., Glen Rock, N.J., pp.
110-129 (1990). Examples of surfactants include copolymers such as
SILWET.RTM. copolymers including Silwet L-7604, available from
Crompton, OSi Specialties division. The copolymers are generally
comprised of ethylene oxide, propylene oxide, and/or silicone.
Other examples of surfactants include 3M FC430 available from 3M of
St. Paul, Minn. and F50-100 available from DuPont Chemicals of
Wilmington, Del.
[0143] Ink Properties
[0144] Inks described herein typically have chemical and physical
properties that allow the inks to be jetted onto a substrate by an
inkjet printer (e.g., by one or more nozzles of a print head of an
inkjet printer).
[0145] In some embodiments, a viscosity of the ink is about 50
centipoise or less (e.g., about 45 centipoise or less, about 35
centipoise or less, about 20 centipoises or less, about 15
centipoises or less) at printing temperature. The viscosity of the
ink may be at least about 1 centipoise (e.g., at least about 5
centipoise, at least about 7 centipoise, at least about 9
centipoises) at printing temperature. During a typical thermal
inkjet printing process, the ink is heated to a printing
temperature of at least about 50.degree. C. (e.g., at least about
60.degree. C., at least about 65.degree. C., at least about
72.degree. C.). Typically, the printing temperature of the ink does
not exceed about 90.degree. C. (e.g., about 85.degree. C., about
80.degree., about 75.degree. C.). For example, in some embodiments,
the printing temperature is between about 65.degree. C. to about
72.degree. C. (e.g., about 68.degree. C.). At jetting temperature,
optimal jetting viscosity is generally based on the print head
being used and is typically specified by the print head
manufacturer.
[0146] In some embodiments, the ink (e.g., a cured mark formed from
the ink) has an modified ASTM 3363 pencil hardness test, with using
of A400 sandpaper from 3M 413Q Wetordry, value of at least 2H
(e.g., at least 3H, at least 4H). For purposes of this application,
the test should be conducted using a VWR precleaned frosted glass
slide Cat. number 48312-013, produced by VWR International, Inc. of
West Chester, Pa., or an equivalent micro glass slide. The model
3363 Pencil Scratch Hardness Tester (from Paul N. Gardner Company,
Inc, Pompano Beach, Fla.) includes a pencil lead holder carried on
two rollers, the weight of which is so arranged that the pressure
exerted by the flat pencil lead is approximately 300 grams. A test
board is placed on a firm horizontal surface and a pencil is then
held firmly against a solder mask at a 45 degree angle. Pencils
grading from 4B (soft) to 9H (hard) can be used to grade the
hardness of the cured mark.
[0147] In some embodiments, the ink (e.g., a cured mark formed of
the ink) passed the acetone wipe test for chemical resistance. In
general, cured samples are double rubbed with a cotton swab wetted
with acetone. The sample is rubbed across the surface with soaked
cotton tipped applicator at least 20 times (or 30, 50 times).
Passing is defined as having no sample come off the substrate.
Failing is defined as sample being easily removed from the
substrate.
[0148] In some embodiments, the ink can pass at least some (e.g.,
all) of the aforementioned tests (e.g., modified ASTM 3363 pencil
hardness, acetone rub) when cured at a speed of about 2 fpm or more
(e.g., about 5 fpm or more, about 10 fpm or more, about 25 fpm or
more, about 35 fpm or more) using a Fusion 300 UV Inc. F300
irradiation with a 300 Watt UV source (e.g., a D lamp and a half
aluminum reflector) after jetting onto a substrate (e.g., a
non-porous substrate such as a glass or a metal).
[0149] Preparing Inks
[0150] To prepare an ink, one can combine all of the composition
ingredients, heat the resulting combination, and if necessary,
mill.
[0151] In some instances, the ink is prepared by blending all
components except for the rheology modifier and pigment. Each clear
sample and rheology modifier is heated (e.g., to about 80.degree.
C.). The rheology modifier is then added to the other components of
the mixture as a liquid to check for solubility, if no solubility
issues are seen then the pigment added, typically as a
concentrate.
[0152] A pigment concentrate can be prepared by combining a pigment
with an amount of at least some (e.g., all) components of an ink to
be prepared to provide a concentrate having a higher concentration
of pigment than the final ink. The pigment concentrate can improve
pigment grinding and reduced process time.
[0153] In the pigment concentrate, the number density of pigment
particles is increased, which allows for more particle-particle and
particle-grinding media collisions, which in turn decreases the
amount of time needed to reach a desired particle size.
Additionally, in the concentrate the particles have higher odds of
coming in contact with dispersant/surfactant molecules if present.
These materials preferably adsorb onto the surface of the particles
so that the reduced size particles do not agglomerate. By
increasing the odds of particle-dispersant collisions, the grind
time can be reduced and the particle size stability can be
increased.
[0154] For example, to prepare a carbon black pigment concentrate,
the amount of dispersant to be used is calculated (the calculation
can be based on the desired pigment particle size, the calculated
pigment surface area (supplied by the pigment manufacturer), or
both). A fluid vehicle and dispersant are charged into an
appropriate vessel. The vehicle and dispersant are mixed until
fully blended (some gentle heating may be necessary if the
dispersant is a solid). The vehicle/dispersant mixture are moved to
a high shear mixer and the pigment is slowly charged. The materials
are milled to obtain the pigment concentrate.
[0155] For a liquid ink, all liquid monomers and oligomers are
mixed, and photoinitiators are added to the mixture. If the
photoinitiators are solid, they are preferably fully dissolved in
the mixture. Then, the pigment concentrate is added to obtain the
liquid ink. If necessary, the ink is filtered through a 1 .mu.m
filter.
[0156] For a solid ink, all monomers and oligomers are heated,
mixed, and photoinitiators are added to the liquefied mixture. If
the photoinitiators are solid, they are preferably fully dissolved
in the mixture. Then, the pigment concentrate is added to obtain
the ink. If necessary, the ink is heated and filtered.
[0157] In some embodiments, an ink is prepared by combining all
components except for the photoinitiating system. The combined
components are heated to facilitate mixing (e.g., to about 70 to
about 80.degree. C.) and milled. The photoinitiating system
component(s) are added to the milled components and the mixture is
filtered. In some cases, the milled components are still warm
(e.g., about 70 .degree. C.) when the photoinitiating system is
added.
[0158] Printing and Curing Methods
[0159] A method of printing (e.g., inkjet printing) and curing an
ink image includes printing an ink composition on a substrate to
form a mark, and curing the mark by exposure to light (e.g.,
visible light, ultraviolet radiation having a wavelength of less
than about 400 nanometers, or a combination thereof).
[0160] Referring to FIGS. 1A-1C, an inkjet printer printing
assembly 10 for printing on a substrate 12 includes a print head 14
having a print head ink reservoir 16, a nozzle 18, and an actuator
15 (e.g., a heat source or piezoelectric element). Assembly 10 also
includes a primary ink reservoir 20 (e.g., a ink cartridge)
connected to print head 14. In use, actuator 15 is actuated (e.g.,
by heating the ink and/or applying oscillatory energy to the ink
within print head reservoir 16) to eject ink (FIG. 1B) from nozzle
18 (e.g., in the form of one or more droplets 22 directed at
substrate 12). Ink that contacts substrate 12 forms a mark 24 (FIG.
1C), which can be cured (e.g., by exposure to light). Although only
one ink composition is shown, the printing assembly can be
configured to print marks formed of each of multiple ink
compositions. Also, the printing assembly can include multiple
nozzles.
[0161] Exemplary substrates include fiber (e.g., wood or paper),
glass, polymers, and printed circuit boards (e.g., a circuit board
from Vermont Circuits, Inc., part number 5454, of Brattleboro,
Vt.).
[0162] For curing the mark(s), a radiation line source can be used
to provide uniform light exposure over a desired area of one or
more substrates. The line source may include an ultraviolet lamp
(e.g., Fusion UV Inc. F300 irradiation with a D lamp and a half
aluminum reflector). Other lamps (e.g., an H lamp or V lamp) may be
used. Other suitable printing and curing means may also be used,
such as methods of printing described in: Leach, R. H., Pierce, R.
J., The Printing Ink Manual, Blueprint (Chapman & Hall), 5th
ed., 1993. An example of a printing system is Markem 4000 system
available from Markem Corp., N.H.
[0163] In some embodiments, one or more marks are applied to a
substrate. The mark(s) is then removed (e.g., by mechanical action
(e.g., wiping), washing, or both). At least one additional mark is
applied to the substrate (e.g., to a location that at least
partially (e.g., mostly or completely) overlies a location occupied
by the previous mark(s)). The additional mark(s) can be essentially
identical in form to the previous marks (e.g., both may have the
same shape or color). The additional mark may differ from the
previous marks substantially (e.g., only) in some properties (e.g.,
color related properties (e.g., tone, hue, or the like) or shape.
The further marks are cured (e.g., by exposure to light). Such an
embodiment can be useful if, for example, one wishes to modify the
appearance (e.g., properties related to color or shape) of a mark
prior to curing the ink of the mark.
[0164] In some embodiments, a mark is exposed to light (e.g., UV
radiation) only after at least about 2 seconds (e.g., at least
about 5 seconds, at least about 10 seconds, at least about 20
seconds, at least about 30 seconds, at least about 1 minute, at
least about 5 minutes, at least about 10 minutes, at least about 30
minutes, at least about 60 minutes, at least about 90 minutes, at
least about 5 hours, at least about 10 hours, at least about 16
hours, or at least about 24 hours.
[0165] In some embodiments, at least one mark is formed on each of
multiple substrates (e.g., at least 2 substrates, at least 3
substrates, at least 5 substrates, at least 10 substrates, at least
25 substrates, at least 50 substrates). After forming the mark(s)
on the multiple substrates, the substrates are cured by exposure to
light.
EXAMPLES
The examples are illustrative, and not intended to be limiting.
Example 1
[0166] UV-Epoxy Inks Including Siloxane Based Monomers
[0167] Ink compositions including UV curable cationic monomers as
shown in Table 1 below were prepared by blending the components of
each sample in a scintillation vial and uniformly heating the vial
to 80.degree. C. This allowed the photoinitiator to be solvated and
mixed with the other materials. All samples were compatible. The
vials with ink compositions were then inverted at least 20 times. A
magnetic stir-bar was placed in each vial, which was then stirred
for about 10-15 minutes with mild heating. The samples were then
cooled and 0.5 militers of ink drawn downs were prepared on a
substrate (glass slides). The draw-downs were run under a Fusion
300 UV-system under a D-bulb (1/2 elliptical aluminum reflector) at
varying belt speeds in feet per minute.
[0168] All samples were tack free immediately after UV exposure and
no surface wrinkling was observed for samples cured at 5 fpm (feet
per minute). Cured samples with different cure speed were tested
for adhesion using the acetone rub and the scratch t est. Of the
PC-series, sample C has the best film properties at 25 fpm,
partially passing the acetone rub. This sample exhibited curing at
up to 250 fpm.
[0169] The formulations of the inks are shown in Table 1 below:
TABLE-US-00001 TABLE 1 Cationic Epoxy Monomer Inks Having an
Siloxane Based Monomers Material A B C PC1000 21% PC2003 11% 32%
Uvacure 1500 32% Erisys GE-21 32% 32% 32% Erisys GE-30 32% 32% 32%
UVI 6992 6% 6% 6%
[0170] A viscosity of each sample was determined using the
Brookfield Programmable Rheometer at 68.degree. C. at 60 rpm using
the #18 spindle. The samples were placed into an aluminum rheometer
vial and placed into the Rheometer. The sample was allowed to
equilibrate at 68.degree. C. for 15 minutes before the data points
were collected. The viscosity of all samples was between
10.about.16 cps at 68.degree. C., except sample C (.about.19 cps),
which was good jettable viscosity by ink jet printer.
Example 2
[0171] UV-Epoxy Inks Including Oxetane Monomers
[0172] Ink compositions comprising at least one of each of two
different oxetane based monomers
(3,3'-oxybis(methylene)bis(3-ethyloxetane) (DOX) and
1,4-bis(((3-ethyloxetan-3-yl)methoxy)methyl)benzene (XDO)) were
prepared. The compositions were prepared as in Example 1, with
heating to 70.degree. C. to facilitate mixing. All samples were
compatible. The compositions are shown in Table 2. TABLE-US-00002
TABLE 2 Epoxy Inks Including Oxetane Based Monomer Material 2A 2B
UVACURE 1500 55.50 55.00 UVI 6992 5 5 9,10-Diethoxy anthracene 0.5
0.5 Dodecyl sulfide 0.3 0.3 Kester K-56 1.5 1.5 TiO2 10 10 DOX
27.20 17.70 XDO 0 10 * values are weight percent
[0173] Draw-downs (0.5 milliliter each) of the ink samples on a
glass slide were exposed under the Fusion 300 UV-system under the
D-bulb (1/2 elliptical aluminum reflector) at 5 fpm. All samples
were tack free immediately after UV exposure and no surface
wrinkling was observed. The samples passed the acetone rub and
scratch test at 5 fpm exposure rates.
[0174] Viscosities were determined using the Brookfield
Programmable Rheometer as per Example 1. The viscosity of
composition 2A was 12.2 cps at 68.degree. C. and the viscosity of
composition 2B was 15.4 cps at 68.degree. C.
[0175] To evaluate jetting performance, compositions 2A and 2B was
loaded into a Nova 300 dpi printhead (Spectra Corporation, Hanover,
N.H.) and jetted at 68.degree. C. Several marks of both
compositions (2A and 2B) were prepared, cured under the D-bulb at 5
fpm with and without post cure heating (5 minute at 110.degree. C.
in oven). The cured marks were tested for performance using the
ASTM 3363 pencil hardness test. The test value on a glass substrate
of all samples was 5H or over.
Example 3
[0176] UV-Epoxy Inks Including Sulfide Initiator
[0177] Ink compositions including different concentration of
dodecyl sulfide were prepared by blending the components of each
sample as described in Example 1. Compositions are shown in Table
3. All samples were compatible. TABLE-US-00003 TABLE 3 Epoxy Inks
Including Sulfide Inhibitor Material 3A 3B 3C 3D UVACURE 1500 38.00
38.00 38.00 38.00 DOX 44.50 44.50 44.50 44.50 TiO.sub.2 10.00 10.00
10.00 10.00 UVI 6992 5 5 5 5 9,10-Diethoxy anthracene 0.5 0.5 0.5
0.5 Kester K-48 2 2 2 2 Dodecyl sulfide 0 0.3 0.5 1 * values are
weight percent
[0178] An amount of each sample (about 50 grams) was stored in a (8
ounce black polypropylene jar) in the dark at a temperature of
70.degree. C. Aliquots of the ink compositions were collected 3, 7,
and 14 days. The viscosity of the ink of each aliquot was
determined using the Brookfield Programmable Rheometer using a #18
spindle. The starting viscosity of each ink was 9.3 cps at
68.degree. C. The viscosities of the inks (68.degree. C.) are shown
in Table 4 below. TABLE-US-00004 TABLE 4 Viscosities of Inks With
Sulfide Inhibitors Sulfide inhibitor Day 3 (cps) Day 7 (cps) Day 14
(cps) 3A 0% 10.6 30.49 Solid gel form 3B 0.3% 9.15 10.4 16 3C 0.5%
9.35 10.05 11.75 3D 1.0% 9.8 10.0 10.2
[0179] After 7 days, the viscosities of compositions 3B, 3C and 3D
were essentially unchanged, while composition 3A was significantly
more viscous. After 14 days, composition 3B exhibited as slight
viscosity increase (about 5 cps), but the viscosities of
compositions 3C and 3D had increased by about 2 cps or less. This
experiment was repeated with the same results.
[0180] All publications, patents, applications, and references
cited herein are hereby incorporated by reference in their
entireties.
[0181] Other embodiments are within the scope of the following
claims. For example, other cationic monomers beside epoxy monomers
can be used in the inks. Examples include vinyl ethers or a
combination of vinyl ethers and epoxy monomers.
* * * * *