U.S. patent application number 17/017949 was filed with the patent office on 2020-12-31 for non-sparking metallic inks and articles printed with same.
This patent application is currently assigned to SUN CHEMICAL CORPORATION. The applicant listed for this patent is SUN CHEMICAL CORPORATION. Invention is credited to Tom DeBartolo, Steven Johnson, Russell Schwartz.
Application Number | 20200407573 17/017949 |
Document ID | / |
Family ID | 1000005080050 |
Filed Date | 2020-12-31 |
United States Patent
Application |
20200407573 |
Kind Code |
A1 |
Schwartz; Russell ; et
al. |
December 31, 2020 |
NON-SPARKING METALLIC INKS AND ARTICLES PRINTED WITH SAME
Abstract
Described herein are metallic pigment-containing inks having a
magnitude of exotherm <1200 J/g, or no observable exotherm at
all. Also described are metallic pigment-containing inks that
include 9.0 wt % or less nitrocellulose resin, or which are
essentially free of nitrocellulose resin. Further described are
articles printed with the described metallic pigment-containing
inks, kits including such inks (and other inks), and methods of
printing with such inks. The metallic pigment-containing ink
described herein reduce, if not eliminate, the tendency of inks
containing metallic pigments to spark and combust.
Inventors: |
Schwartz; Russell;
(Cincinnati, OH) ; DeBartolo; Tom; (Monroe,
NC) ; Johnson; Steven; (Fairfield, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUN CHEMICAL CORPORATION |
Parsippany |
NJ |
US |
|
|
Assignee: |
SUN CHEMICAL CORPORATION
Parsippany
NJ
|
Family ID: |
1000005080050 |
Appl. No.: |
17/017949 |
Filed: |
September 11, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16303303 |
Nov 20, 2018 |
10800935 |
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PCT/US17/33917 |
May 23, 2017 |
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17017949 |
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62340050 |
May 23, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 5/00 20130101; C08K
3/08 20130101; C09D 11/037 20130101; C09D 11/033 20130101; C09D
11/106 20130101; C08K 3/28 20130101; C09D 11/102 20130101 |
International
Class: |
C09D 11/037 20060101
C09D011/037; C08K 3/28 20060101 C08K003/28; C08K 3/08 20060101
C08K003/08; C08K 5/00 20060101 C08K005/00; C09D 11/033 20060101
C09D011/033; C09D 11/102 20060101 C09D011/102; C09D 11/106 20060101
C09D011/106 |
Claims
1-25. (canceled)
26. A metallic pigment-containing ink comprising a metallic
pigment, wherein the ink exhibits a magnitude of exotherm less than
1200 J/g, or does not exhibit an observable exotherm, and wherein
the ink is essentially free of nitrocellulose resin.
27. The metallic pigment-containing ink of claim 26, wherein the
metallic pigment is selected from aluminum, bronze, copper, brass,
silver, gold, and combinations thereof.
28. The metallic pigment-containing ink of claim 26, wherein the
metallic pigment is an aluminum pigment.
29. The metallic pigment-containing ink of claim 26, wherein the
metallic pigment is a non-leafing aluminum pigment.
30. The metallic pigment-containing ink of claim 26, further
comprising one or more resins selected from the group consisting of
acrylates, methacrylates, polyurethanes, polyvinyl butyrals,
polyesters, cellulose acetate propionates, polyamides, vinyls, and
combinations thereof.
31. The metallic pigment-containing ink of claim 26, further
comprising one or more solvents selected from aliphatic
hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, ketones,
aldehydes, alcohols, ethers, esters, and combinations thereof.
32. The metallic pigment-containing ink of claim 26, further
comprising a colorant.
33. The metallic pigment-containing ink of claim 26, further
comprising an additive selected from the group consisting of
adhesion promoters, de-gassing additives, flow promoters,
defoamers, antioxidants, surfactants, dispersants, plasticizers,
rheological additives, anti-static agents, waxes, silicones, and
combinations thereof.
34. The metallic pigment-containing ink of claim 26, further
comprising an alcohol solvent, an acetate solvent, and a polyvinyl
butyral resin.
35. The metallic pigment-containing ink of claim 26, further
comprising an alcohol solvent, an acetate solvent, and an acrylic
resin.
36. The metallic pigment-containing ink of claim 26, further
comprising cellulose acetate propionate resin.
37. The metallic pigment-containing ink of claim 26, further
comprising an alcohol solvent, an acetate solvent, an ether alcohol
solvent, a polyurethane resin, and a polyvinyl butyral resin.
38. The metallic pigment-containing ink of claim 26, wherein the
polyurethane resin is a polyether polyurethane resin
39. The metallic pigment containing ink of claim 26, further
comprising an alcohol solvent, an ether alcohol solvent, and a
polyamide resin.
40. A printed article comprising: a substrate; and the metallic
pigment-containing ink of claim 26, printed on the substrate.
41. The printed article of claim 40, wherein the substrate is a
material selected from polypropylene, polyvinyl chloride, oriented
polystyrene, polyethylene terephthalate, glycol-modified
polyethylene terephthalate, and polylactic acid.
42. A kit of inks for printing articles with a metallic
pigment-containing ink comprising: one or more of the metallic
pigment-containing inks of claim 26; and one or more inks that do
not include a metallic pigment.
43. A printed article comprising: a substrate; at least one
metallic pigment-containing ink provided in the kit of claim 42
printed on the substrate; and at least one ink that does not
include a metallic pigment provided in the kit of claim 42 printed
on the substrate.
44. The printed article of claim 43, wherein the substrate is a
material selected from polypropylene, polyvinyl chloride, oriented
polystyrene, polyethylene terephthalate, glycol-modified
polyethylene terephthalate, and polylactic acid.
45. A method of printing an article, comprising: providing a
substrate; printing a metallic pigment-containing ink according to
claim 26, on the substrate.
46. The method of claim 45, wherein the substrate is a material
selected from polypropylene, polyvinyl chloride, oriented
polystyrene, polyethylene terephthalate, glycol-modified
polyethylene terephthalate, and polylactic acid.
47. The method of claim 45, wherein the printing is selected from
flexographic printing and gravure printing.
48. A method of printing an article, comprising: providing a
substrate; and printing, in a selected series, at least one
metallic pigment-containing ink provided in the kit of claim 42 on
the substrate; and at least one ink that does not include a
metallic pigment provided in the kit of claim 42 printed on the
substrate.
49. The method of claim 48, wherein the substrate is a material
selected from polypropylene, polyvinyl chloride, oriented
polystyrene, polyethylene terephthalate, glycol-modified
polyethylene terephthalate, and polylactic acid.
50. The method of claim 48, wherein the printing is selected from
flexographic printing and gravure printing.
51. The method of claim 48, wherein at least one metallic
pigment-containing ink and the at least one ink that does not
include a metallic pigment comprise resins that are different from
each other.
Description
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 62/340,050, filed May 23, 2016, which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present application is directed to the field of printing
inks, printed articles, and methods of printing articles,
particularly involving metallic pigment-containing printing inks.
Such printing inks are suited for application by, for example,
flexographic and gravure printing methods.
BACKGROUND OF THE INVENTION
[0003] Metallic pigment-containing inks, such as those containing
aluminum pigments, provide a very attractive appearance to printed
articles. Metallic pigment-containing inks provide printed articles
with a striking metallic appearance that exhibits shine, gloss, and
reflectance. Metallic pigment-containing inks have been known to
include nitrocellulose resin as a binder resin and a solvent.
Relatively large amounts of nitrocellulose resin are included in
such inks.
[0004] Metallic pigment-containing inks are susceptible to sparking
during printing, which can lead to combustion and fire. For
example, in high speed printing operations, such inks may spark and
combust on the printing press, causing fire that damages the press,
printed materials, and/or the surrounding area. The sparking of the
ink may occur as it is being applied to the substrate. Thus,
metallic pigment-containing inks have been known to present a
workplace hazard, despite the beneficial properties they
possess.
[0005] As the ink moves through the press, it flows past a doctor
blade which removes excess ink. At fast press speeds, the action of
the doctor blade creates friction on the surface of the inked
substrate, which can lead to sparking of the ink. Thus, the action
of, for example, a stainless steel doctor blade, in motion to
remove excess ink and contacting the metallic pigment-containing
ink (e.g., aluminum pigment-containing ink), creates friction that
can lead to sparking and combustion.
[0006] Many printing operations occur at high speeds, thus the
problem encountered when metallic pigment-containing inks are used
is a real concern. Such substrate materials include, for example,
polypropylene (PP), polyethylene terephthalate (PET) and polyamide
materials. The printing press, such as a flexographic or
rotogravure press, can run at speeds up to about 2600 feet per
minute (fpm).
[0007] One possible approach to alleviating the sparking and
combustion problem would be to dilute the ink formulation with
water. However, adding water into a metallic pigment-containing ink
does not effectively reduce the potential for sparking and
combustion. To the contrary, adding water may exacerbate the
problem. Hydrogen may be generated when, for example, an ink
containing aluminum comes in contact with water. Hydrogen is
potentially explosive and itself is a combustible material.
[0008] Thus, there is a need for a metallic ink composition for
printing packaging such as flexible packaging that overcomes the
disadvantages such inks, and in particular, the safety hazards that
they present.
SUMMARY OF THE INVENTION
[0009] In one inventive aspect, described herein are metallic
pigment-containing inks comprising a metallic pigment, wherein the
inks exhibit a magnitude of exotherm less than 1200 J/g, or which
do not exhibit an observable exotherm. In yet a more particular
inventive aspect, the metallic pigment-containing inks comprise,
based on the total weight of the ink, 9.0 wt % or less of
nitrocellulose resin, or are essentially free of nitrocellulose
resin.
[0010] In another inventive aspect, described herein are metallic
pigment-containing inks comprising a metallic pigment, wherein,
based on the total weight of the ink, the ink comprises 9.0 wt % or
less of nitrocellulose resin, or the inks are essentially free of
nitrocellulose resin. In yet a more particular inventive aspect,
the metallic pigment-containing inks exhibit a magnitude of
exotherm less than 1200 J/g, or does not exhibit an observable
exotherm.
[0011] In yet another inventive aspect, described herein are
metallic pigment-containing inks comprising a metallic pigment, one
or more solvents, and one or more resins, wherein the inks are
essentially free of nitrocellulose resin; or the inks include only
a relatively small amount of nitrocellulose resin, e.g., 9.0 wt %
nitrocellulose resin or less. Such inks may be free of antistatic
additives, or contain only small amounts of same, which is
advantageous because such additives may adversely affect dry ink
film properties.
[0012] In yet still another inventive aspect, described herein are
combinations of inks comprising one or more metallic
pigment-containing inks as described herein and one or more colored
inks that do not include a metallic pigment. But for the
considerations regarding nitrocellulose resin content (or absence
thereof) in metallic pigment-containing inks, the resin systems may
be the same or different for metallic pigment-containing inks and
inks that do not include metallic pigments. Such ink combinations
may be provided in a kit of inks.
[0013] In even yet still another inventive aspect, described herein
are printed articles comprising a substrate on which the metallic
pigment-containing inks described herein is printed. Also described
are printed articles in which inks from the kits described herein
are printed onto substrates.
[0014] In even yet still another further inventive aspect,
described herein are methods for printing articles in which the
metallic pigment-containing inks described herein are printed onto
substrates. Also described are methods in which inks from the kits
described herein are printed onto substrates.
[0015] When working with ink combinations, e.g., kits of inks, such
inks may be deposited onto a substrate material in a chosen order,
e.g., in a chosen series of inks. The metallic pigment-containing
ink may be as described above, e.g., may include no nitrocellulose
resin or a small amount thereof. Combinations of inks, metallic
inks and non-metallic inks may be provided in kits. Such ink
combinations may provide benefit and efficacy over the mixed
solvent (i.e. solvent and water) approach to formulating inks which
do not necessarily alleviate the hazard, such as for example the
unsafe condition of having an ink composition including aluminum
pigment and water.
[0016] The non-metallic pigment-containing ink may be any
commercially available ink, such as the ones identified for
exemplary purposes later in this disclosure.
[0017] The applicants have surprisingly found that the presence of
nitrocellulose resin in an ink that includes a metallic pigment may
increase the susceptibility of the ink to sparking, which could
result in combustion. The susceptibility to sparking may be
dependent upon the amount of nitrocellulose resin in the metallic
pigment containing ink composition. This finding is surprising
because the person of ordinary skill in the art might not suspect
that sparking was attributable to the amount of nitrocellulose
resin in the ink. One way that the skilled person might try to
solve the problem is by adding an anti-static agent to the ink, or
by increasing the amount of anti-static agent in the
composition.
[0018] From the finding that reducing or eliminating nitrocellulose
resin in metallic pigment-containing inks eliminates the sparking
and combustion problem, the applicants further realized that
benefits could be attained from changing the entire set of inks
used in a printing process. Inks are typically printed in
combinations that are applied to a substrate. Further, different
resin compositions often require different solvent blends to
maintain ink viscosity throughout a press run. Thus, different inks
with different resins and solvents may be printed on a substrate.
The applicants have found that combinations of inks, e.g., one or
more metallic pigment containing inks and one or more inks not
including metallic pigments (ordinarily including another colorant)
can be printed onto the same substrate in the same printing job,
even though the inks of the combination may not employ the same
resin systems. This finding is surprising. Generally, one skilled
in the art may not use a combination of inks in which the inks
include different resin systems. Combining inks of different resin
systems in printing an article has been known to provide an
inferior and/or unacceptable printed article characterized by poor
compatibility of the ink combination, poor adhesion of one or more
of the inks, poor runnability, and trapping problems. Runnability
relates to the ability of an ink to print well and provide a defect
free print, such as defect-free texts, logos, etc. Trapping refers
to the printability of one ink over another, such as in process
printing in which four (4) colors which are "trapped" providing a
palette of many colors that result from the trapping.
[0019] Yet, in printing with the ink combinations described herein,
which include the presently described metallic pigment-containing
inks containing nitrocellulose resins in small amounts (or which
are essentially free thereof), the sparking and combustion problem
is solved and metallic pigment-containing inks can be
provided--alone or in kits of inks--that do not present a safety
hazard. The non-metallic inks of the combination may be formulated
to be free of nitrocellulose resin or contain very little thereof,
which further aids in eliminating the likelihood of sparking and
combustion when printed on a printing press.
[0020] The Applicants have found that inventive inks of the present
disclosure have been used for a period of time on a flexographic or
gravure machine for several months and there have been no incidents
of sparking and combustion during printing operations.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Metallic pigment-containing inks are described herein.
Articles printed with metallic pigment-containing inks have an
aesthetically pleasing metallic appearance. Such inks may impart
one or more of shininess, glossiness, reflectiveness, and/or an
overall metallic appearance to a printed article such as a label,
package, design, etc. Metallic pigment-containing inks are
printable on conventional substrates, such as polypropylene (OPP),
polyvinylchloride (PVC), oriented polystyrene (OPS), polyethylene
terephthalate (PET), glycol-modified polyethylene terephthalate
(PET-G) and polylactic acid (PLA) film, and other materials.
[0022] As noted, metallic pigment-containing inks heretofore known
in the art may spark during printing, such as during printing on a
flexographic or gravure printing press. This could lead to
combustion, fire and/or explosion. The sparking may be caused by
heating, static electricity, or some other effect. As indicated,
the applicants surprisingly found that the problem appears to be
associated with the amount of nitrocellulose resin present in the
metallic pigment-containing ink formulations.
[0023] The present metallic pigment-containing inks are comprised
of a metallic pigment, a resin system comprising one or more
resins, and a solvent system comprising one or more solvents.
Additional non-metallic pigment colorants may also be included.
Other additives that are commonly found in inks compositions may
also be included in the present metallic pigment-containing inks,
and anti-static agents. Advantageously, the metallic
pigment-containing inks described herein are essentially
nitrocellulose resin free, or include only a small amount of
nitrocellulose resin.
[0024] The metallic pigment-containing inks described herein
contain no more than 9.0 wt % nitrocellulose resin, that is, they
contain 0.01 wt % to 9.0 wt % nitrocellulose resin; more preferably
0.01 wt % to 7.5 wt % nitrocellulose resin; 0.01 wt % to 5.0 wt %
nitrocellulose resin; still more preferably 0.01 wt % to 2.5 wt %
nitrocellulose resin; and even still more preferably 0.01 wt % to
1.0 wt % nitrocellulose resin. These amounts are based on the (1)
the nitrocellulose resin solids content, e.g., a commercially
available nitrocellulose resin products may contain an amount of
nitrocellulose resin solids and a liquid medium, such as an water
or an organic liquid, and the amounts of nitrocellulose resins are
indicative of the amount of nitrocellulose resin solids in the
products; and (2) the ink compositions as formulated, inclusive of
solvent(s) included in formulating the inks. For example, the
metallic pigment-containing ink composition may include one or more
solvents. The amounts of nitrocellulose resin indicated herein are
based on the formulations of the inks that are inclusive of the
solvent(s), that is the amounts reflect the nitrocellulose resin
content prior to solvent removal that may occur, such as by one or
more of evaporation, drying, heating, or other means. Such solvent
removal may occur during printing after the ink is applied to a
substrate, such as by drying at the ambient temperature or by
drying with heat. These concepts are embodied in the examples that
follow.
[0025] By "essentially nitrocellulose resin-free" or "essentially
free of nitrocellulose resin" it is meant that there is 0-0.01 wt %
nitrocellulose resin solids content in the ink, subject to the
concepts expressed above. These terms are used interchangeably
herein. "Nitrocellulose resins solids content" is explained below.
These terms are inclusive of no nitrocellulose resin being present
in the inks and coatings. Preferably, there is 0 wt %
nitrocellulose in the metallic pigment-containing inks.
[0026] The applicants have found that when the amount of
nitrocellulose resin content in the metallic pigment-containing
inks is 9.0 wt % or less, or when the ink is essentially free of
nitrocellulose resin, then the likelihood of the ink composition
sparking, igniting, combusting, and/or exploding is significantly
reduced, if not completely eliminated. Applicants have found that
metallic pigment-containing ink compositions that meet the
nitrocellulose resin criteria of 9.0 wt % or less can be safely
used on a high speed printing press, such as a flexographic or
gravure printing presses. In fact, such inks have been used for
months on printing operations on such presses without the
occurrence of safety endangering incidents.
[0027] In one aspect, the ratio of metallic pigment to
nitrocellulose resin, when nitrocellulose resin is present, is in
the range of 1:0.50 to 1:32.50, on a weight to weight basis. In
another aspect, the ratio of metallic pigment to nitrocellulose
resin is 1:0.60 to 1:27.50. In another aspect, the ratio of
metallic pigment to nitrocellulose resin is 1:0.75 to 1:22.50. In
another aspect, the ratio of metallic pigment to nitrocellulose
resin is 1:0.90 to 1:18.50.
[0028] Any kind of metallic pigment may be used in ink compositions
described herein. Preferably, the metallic pigment is an aluminum
pigment, more preferably, a non-leafing aluminum pigment. Other
kinds of metallic pigments may be used. The metallic pigment may
be, for example, copper, silver, gold, copper-zinc alloys (e.g.,
brass), copper-tin alloys (e.g., bronze), stainless steel, carbon
steel, iron, silver, zinc, nickel, titanium, chromium, manganese,
vanadium, magnesium, zinc-magnesium alloys, and mixtures thereof.
Combinations of metallic pigments may be used. For example, the
metallic pigments may be a combination of aluminum and bronze.
[0029] A leafing pigment is a pigment that is localized at the top
of the surface of the ink, whereas a non-leafing pigment is a
pigment that is evenly distributed through the ink. Leafing
pigments maybe coated with stearic acid or other saturated fatty
acids, while non-leafing pigments are coated with oleic and other
unsaturated fatty acids.
[0030] In some embodiments, the metallic pigment comprises a
lubricant that is a residual from pigment manufacture. Suitable
lubricants include, but are not limited to, saturated and
unsaturated fatty acids.
[0031] In some embodiments, the metallic pigment is coated with one
or more metal oxides. Metal oxides used to coat the metallic
pigment include, but are not limited to, silicon dioxide, titanium
dioxide, zinc oxide, zirconium dioxide, tin oxide, cerium dioxide,
vanadium oxide, manganese oxide, lead oxide, chromium oxide, iron
oxide, aluminum oxide, tungsten oxide, and hydroxides and mixtures
thereof. In some embodiments, the coating comprises a hydrated
oxide of any one of the aforementioned oxides. In some embodiments,
the coating is also doped with an oxide of another metal, such as
one or more of the aforementioned metals. The thicknesses of the
metal oxide layers vary. In some embodiments, the thickness of the
metal oxide layers is in the range of about 20 nm to about 400 nm.
In some embodiments the metal oxide layers are partially
transparent.
[0032] In some embodiments, the metallic pigment may be platelet-
and/or flake-shaped. In some embodiments, the metallic pigment has
a d50 (median particle diameter) in the range of about 1 .mu.m to
about 500 .mu.m, such as about 5 .mu.m to about 500 .mu.m, about 1
.mu.m to about 400 .mu.m, about 1 .mu.m to about 300 .mu.m, about 1
.mu.m to about 250 .mu.m, about 1 .mu.m to about 100 .mu.m, or
about 5 .mu.m to about 100 .mu.m. Median particle diameter d50 is
measured by dynamic light scattering. In some embodiments, the
average thickness (h50) of the metallic pigment is in the range of
about 1 nm to about 5 .mu.m, such as about 10 nm to about 5 .mu.m,
about 50 nm to about 5 .mu.m, about 1 nm to about 2 .mu.m, about 1
nm to about 1 .mu.m, about 1 nm to about 500 nm or about 10 nm to
about 500 nm. The h50 is measured by scanning electron microscopy.
The metallic pigment may also be of any type of class of metallic
pigment. In some embodiments the shape of the metallic pigment is
described for example as cornflake, silver dollar, or vacuum
metalized flake (VMP). In some embodiments, pigment is described as
leafing or non-leafing.
[0033] The resins of the resin system employed in the metallic ink
formulation may be one or more resins used in ink formulations.
Preferred resins to be used in the resin systems used in
formulating the metallic pigment-containing ink compositions
include, by way of example, acrylate resins, methacrylate resins,
polyurethane resins, polyvinyl butyral (PVB) resins, polyester
resins, cellulose acetate propionate resins, polyamide resins,
vinyl resins (e.g., polystyrene resins), rosins, shellacs,
cellulose acetate butyrate (CAB), ethyl cellulose, and polyketones.
Nitrocellulose resin may be included in the metallic
pigment-containing inks in the limited amounts described above.
Combinations of resins may be employed. In a preferred embodiment,
the metallic pigment-containing ink composition includes one or
more polyurethane resins. In a more preferred embodiment, the
polyurethane resin or resins are the primary resin or sole resins
of the ink compositions.
[0034] In one inventive aspect, the metallic pigment-containing
inks exhibit a magnitude of exotherm of less than 1200 J/g, or
exhibit no observable exotherm. While not wishing to be bound by
any theory, applicants believe that this may be related to, as
described above, using only a small amount of nitrocellulose resin
in the compositions of the metallic pigment-containing inks, or by
keeping such inks essentially nitrocellulose resin free. In the
examples of inventive metallic pigment-containing inks that follow,
it is shown that such inks do not spark, and are thus much safer to
use, while retaining the printability, excellent visual appearance,
and dry film benefits such as resistance to scratches, rub removal,
etc., of compositions that include nitrocellulose resin.
[0035] The solvent system used in the metallic ink compositions may
be any solvent commonly used in formulating an ink composition, or
combinations thereof. Such solvents include, for example, aliphatic
hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, ketones,
aldehydes, alcohols, ethers, and esters. Again, combinations of
solvents may also be used. The solvent system for the ink
compositions that do not include a metallic pigment used in
combination with a metallic pigment-containing inks may also be may
be any solvent commonly used in formulating an ink composition, or
combinations thereof. Such solvents include, for example, aliphatic
hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, ketones,
aldehydes, alcohols, ethers, and esters. Again, combinations of
solvents may also be used.
[0036] Additives commonly included in inks may be included in the
metallic pigment-containing inks and non-metallic
pigment-containing inks described herein. Such additives are
exemplified by adhesion promoters, light stabilizers, de-gassing
agents, flow promoters, defoamers, antioxidants, UV stabilizers,
surfactants, dispersants, plasticizers, rheological additives,
waxes, silicones, anti-static agents, to name a few.
[0037] Colorants other than the metallic pigment may also be
included in the metallic pigment-containing ink, and in the inks
that do not include metallic pigments. Such colorants include, for
example, organic or inorganic pigments and dyes. The dyes include
but are not limited to fluorescent dyes, azo dyes, anthraquinone
dyes, xanthene dyes, azine dyes, and combinations thereof. Organic
pigments may be one pigment or a combination of pigments, such as
for instance Pigment Yellow Numbers 12, 13, 14, 17, 74, 83, 114,
126, 127, 174, 188; Pigment Red Numbers 2, 22, 23, 48:1, 48:2, 52,
52:1, 53, 57:1, 112, 122, 166, 170, 184, 202, 266, 269; Pigment
Orange Numbers 5, 16, 34, 36; Pigment Blue Numbers 15, 15:3, 15:4;
Pigment Violet Numbers 3, 23, 27; and/or Pigment Green Number 7.
Inorganic pigments may be one of the following non-limiting
pigments: iron oxides, titanium dioxides, chromium oxides, ferric
ammonium ferrocyanides, ferric oxide blacks, Pigment Black Number 7
and/or Pigment White Numbers 6 and 7. Other organic and inorganic
pigments and dyes can also be employed, as well as combinations
that achieve the colors and/or effects desired.
[0038] In one inventive aspect, a metallic pigment containing ink
may have the following composition:
[0039] 3 to 35 wt % metallic pigment;
[0040] 4 to 25 wt % resin system, e.g., one or more resins;
[0041] 10 to 95 wt % solvent system, e.g., one or more
solvents;
[0042] 0.1 to 20 wt % colorant system, e.g., one or more colorants;
and
[0043] 0.1 wt % to 15 wt % additional additives.
[0044] The metallic pigment containing inks may be used in
combination with other kinds of inks, e.g., inks that do not
include a metallic pigment. The other inks may be any commercially
available ink products that are compatible for use with the
metallic pigment-containing inks described herein. For example, the
present metallic pigment-containing inks are preferably used in
flexographic and gravure printing operations; thus, the
commercially available inks not including metallic pigments should
be compatible for use a flexographic or gravure printing operation.
The combinations of inks can be provided in kits of inks. Suitable
commercially available inks not including metallic pigments
include, for example: SunSpectro Solvaplast 901, SunSpectro
Sunsharp, SunStrato DPT-285, Sunstrato Flexomax, SunStrato DPX-377,
SunStrato Rotopure, SunStrato Excelbond, SunStrato Nulam, and
SunSpectro Harmony. SunSpectro Aquaking, SunVisto Advantage,
SunVisto Ultrasak, and SunStrato AquaBond.
[0045] As indicated, the metallic pigment-containing inks exhibit a
magnitude of exotherm that is less than 1200 Joules/gram (J/g)
according to the test method described below, e.g., a magnitude of
exotherm of 0.01 J/g to 1200 J/g, or no observable magnitude of
exotherm. The Applicants have found that the inventive metallic
pigment-containing inks disclosed herein that meet these criteria
are less susceptible to combusting and thus pose substantially less
of a safety hazard, e.g., they are less likely to spark, combust,
catch fire, and/or explode when running on a printing press.
[0046] In one aspect of the present disclosure, and in accordance
with the test methods described below, preferably the metallic
pigment-containing inks exhibit a magnitude of exotherm that is
0.01 J/g to 1100 Joules/gram (J/g); more preferably the metallic
pigment-containing inks exhibit a magnitude of exotherm that is
0.01 J/g to 1000 Joules/gram (J/g); still more preferably the
metallic pigment-containing inks exhibit a magnitude of exotherm
that is 0.01 J/g to 800 Joules/gram (J/g); even still more
preferably the metallic pigment-containing inks exhibit a magnitude
of exotherm that is 0.01 J/g to 600 Joules/gram (J/g); yet even
still more preferably the metallic pigment-containing inks exhibit
a magnitude of exotherm that is 0.01 J/g to 200 Joules/gram (J/g);
yet even further still more preferably the metallic
pigment-containing inks exhibit a magnitude of exotherm that is
0.01 J/g to 100 Joules/gram (J/g); and yet more further preferably
the metallic pigment-containing inks exhibit no observable
magnitude of exotherm.
[0047] In one embodiment, the present invention comprises a
combination of inks printed on a substrate, the combination
comprising at least one metallic pigment-containing ink and at
least one ink not containing a metallic pigment. The metallic
pigment-containing inks exhibit a magnitude of exotherm that is
0.01 J/g to 1200 J/g, or exhibit no observable magnitude of
exotherm. The preferred ranges for magnitude of exotherm, including
observing no exotherm, is as provided above.
[0048] In another embodiment, the present invention comprises a
series of flexographic or gravure inks comprising at least one
metallic pigment-containing ink and at least one non-metallic ink
wherein the at least one metallic ink optionally has a small amount
of nitrocellulose resin (e.g., 9.0 wt % or less, as described
above). Metallic inks with 9.0 wt % or less nitrocellulose resin
are shown to be less prone to sparking and thus present a decreased
fire and explosion hazard.
[0049] The metallic pigment-containing inks or the present
disclosure are described in relation to inks suitable for printing
according to the flexographic and gravure print processes. It
should be readily understood that the presently described metallic
pigment containing inks can also be printed by other print
processes and used with the equipment employed in same, such as
lithography, offset printing, screen printing, digital printing
(e.g., ink jet printing), and printing employing energy curing
(e.g., UV-curing and electron beam curing). It should be understood
that the ink formulation may have to be modified when used in other
printing processes, such as by adjusting the formulation
accordingly, or adding additional components to same in order to
adjust ink viscosity and/or provide for a performance capability
(e.g., include ethylenically unsaturated monomers, etc. and
photoinitiators to provide for energy curing capabilities).
[0050] In another embodiment, the metallic pigment-containing inks
are essentially free of nitrocellulose resin.
[0051] The following examples are intended to exemplify ink
compositions that come within the scope of the disclosure, and to
show the benefits that such exemplary compositions possess. The
examples should not be construed as limiting the scope of the
invention.
EXAMPLES
[0052] All amounts of components are wt % amounts, unless otherwise
noted.
Example 1 (Inventive)
[0053] A metallic pigment-containing ink composition that is free
of nitrocellulose resin, includes polyvinyl butyral resin, and is
suitable for flexographic printing was prepared as follows:
[0054] An intermediate was prepared by mixing the following
ingredients:
TABLE-US-00001 TABLE 1 Example 1A Intermediate Material wt % ETHYL
ALCOHOL 74.3 ISOPROPYL ALCOHOL 8.4 NORMAL PROPYL ACETATE 0.8 BL-1,
POLYVINYL BUTYRAL (Sekisui) 14.7 AMINO SILANE Z6020 (Dow) 0.8
Ortho- and Para-TOLUENE SULFONAMIDE (Ritchem) 1.0 Total 100.0
[0055] The Example 1A intermediate was mixed with the following
ingredients to produce a finished ink:
TABLE-US-00002 TABLE 2 Example 1B Metallic Ink Material wt %
Example 1A Intermediate 57.7 NORMAL PROPYL ALCOHOL 18.5 NORMAL
PROPYL ACETATE 4.6 6282 .RTM. BENDA LUTZ METALLIC PIGMENT 19.2
Total 100.0
[0056] 6282.RTM. BENDA LUTZ is a non-leafing aluminum pigment. The
intermediate and the final ink formulations were mixed with a
Cowles mixer.
Example 2 (Comparative): Nitrocellulose Resin-Based Ink
[0057] An intermediate was prepared by mixing the following
ingredients:
TABLE-US-00003 TABLE 3 Example 2A Intermediate Material % NORMAL
PROPYL ALCOHOL 24.25 GEN III Nitro Varnish (Example 2B) 45.65
UNIREZ 2248 (Arizona Chemical) 0.700 UNIREZ 2221 (Arizona Chemical)
0.70 HERCOLYN D (Pinova) 1.30 DIBUTYL SEBACATE 1.30 DIACETONE
ALCOHOL 3.00 PROPASOL SOLVENT P 3.00 ETHYL ALCOHOL SDA-3C 20.10
Total 100.00
PROPASOL SOLVENT P is propylene glycol n-propyl ether.
[0058] A second intermediate was prepared by mixing the following
ingredients:
TABLE-US-00004 TABLE 4 Example 2B GEN III Nitro Varnish Material %
NORMAL PROPYL ALCOHOL 30 NORMAL PROPYL ACETATE 30 .sup.1DMX 3-5
NITROCELLULOSE 40 (Nobel) Total 100 .sup.170% resin solids/30%
isopropyl alcohol
[0059] The intermediates of Examples 2A and 2B were mixed with the
following ingredients to produce a finished ink suitable for
flexographic printing:
TABLE-US-00005 TABLE 5 Example 2C Metallic Ink Material % Example
2A Intermediate 79.3 Example 2B Nitro Varnish 9.4 6282 .RTM. BENDA
LUTZ METALLIC PIGMENT 11.3 Total 100.0
Example 3 (Inventive)
[0060] A non-nitrocellulose resin, acrylic-based ink suitable for
flexographic printing was prepared as follows as an
intermediate:
TABLE-US-00006 TABLE 6 Example 3A Extender Material % NORMAL PROPYL
ALCOHOL 44.18 NORMAL PROPYL ACETATE 25.84 NEOCRYL B-814 ACRYLIC
(DSM Resins) - 10.72 a resin CELLULOSE ACETATE PROPIONATE 8.50
CAP-504-0.2 (EASTMAN) - a resin 30RES-ACR-2013 ACRYLIC (Lucite
Corp) - a 2.08 resin ORTHOPARATOLUENE SULFANOMIDE 3.00 PLASTICIZER
GAMMA-BUTYROLACTONE 2.68 PM ACETATE 3.00 Total 100.00
[0061] The Example 3A intermediate was mixed with the following
ingredients to produce a finished ink:
TABLE-US-00007 TABLE 7 Example 3B Metallic Ink Material % Example
3A EXTENDER 88.7 6282 .RTM. BENDA LUTZ METALLIC 11.3 PIGMENT Total
100.0
Example 4 (Inventive) a Non-Nitrocellulose Resin, Urethane-Based
Metallic Ink
[0062] An intermediate was prepared by mixing the following
ingredients:
TABLE-US-00008 TABLE 8 Example 4A Urethane Extender Material %
POLYETHER POLYURETHANE 64 NORMAL PROPYL ALCOHOL 21 PROPASOL SOLVENT
P 5 ETHOXYPROPANOL 5 TV97-7111: 25% POLYVINYL 5 BUTYRAL SOLUTION
(Kuraray America) Total 100
[0063] TV97-7111:25% polyvinyl butyral solution is a 25 wt % solids
resin solution of polyvinyl butyral (PVB) resin.
[0064] The Example 4 intermediate was mixed with the following
ingredients to produce a finished ink suitable for flexographic
printing:
TABLE-US-00009 TABLE 9 Example 4B Metallic Ink Material % EXAMPLE 4
INTERMEDIATE 88.7 6282 .RTM. BENDA LUTZ METALLIC 11.3 PIGMENT Total
100.0
Examples 5-10 and Comparative Examples 2C and 3-5: Flexographic
Metallic Ink Examples with Varying % of Nitrocellulose Resin
[0065] Additional examples were prepared as described above, using
the components listed in Table 10. The amount of nitrocellulose
resin was varied from example to example. Comparative Example 2C is
of the same composition as described above. The compositions are
reported in Table 10 below.
TABLE-US-00010 TABLE 10 Example Example Example Example Example
Example 2C Comp. Comp. Comp. 5 6 7 8 9 10 (Comp.) Ex. 3 Ex. 4 Ex. 5
(Inv.) (Inv.) (Inv.) (Inv.) (Inv.) (Inv.) 320-7: Normal Propyl
Alcohol 19.20 21.50 21.50 21.50 24.20 25.05 29.55 30.10 35.90 39.75
Example 2B Varnish (28% 45.60 38.70 35.50 32.85 28.40 25.25 18.85
15.10 8.00 1.35 nitrocellulose solids) 938-181: Unirez 2248 0.55
1.15 1.85 2.75 3.65 4.80 5.75 7.35 8.00 9.40 (polyamide) 938-193:
Unirez 2221 0.55 1.15 1.85 2.75 3.65 4.80 5.75 7.35 8.00 9.40
(polyamide) 390-79: Hercolyn D (plasticizer) 1.05 1.15 1.15 1.15
1.15 1.15 1.15 1.15 1.15 1.15 390-55: Dibutyl Sebacate 1.05 1.15
1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 (plasticizer) 320-57:
Diacetone Alcohol 2.40 2.65 2.65 2.65 2.65 2.65 2.65 2.65 2.65 2.65
320-217: Propylene glycol n- 2.40 2.65 2.65 2.65 2.65 2.65 2.65
2.65 2.65 2.65 propyl ether 320-263: Ethyl Alcohol 15.90 18.60
20.40 21.25 21.20 21.20 21.20 21.20 21.20 21.20 6282 .RTM. BENDA
LUTZ metallic 11.30 11.30 11.30 11.30 11.30 11.30 11.30 11.30 11.30
11.30 pigment Total 100.00 100.00 100.00 100.00 100.00 100.00
100.00 100.00 100.00 100.00 Total % nitrocellulose in 12.8 10.8 9.9
9.2 8 7.1 5.3 4.2 2.2 0.4 formulation Comp. = comparative; Inv. =
inventive
[0066] The above metallic finished inks were flexographically
printed onto oriented polypropylene (OPP) using a 7.0 BCM (billion
cubic microns) anilox.
Example 11--Impact Sparking Test
[0067] The following test was performed to see if the compositions
will spark. A clean, two-inch stainless steel ball bearing was dip
coated in one of the ink compositions of Table 10 to form a
metallic ink film on the ball bearing. The film was dried at room
temperature for 16 hours prior to the impact spark test. After
drying, the coated ball bearing was impacted with a second,
uncoated, but otherwise identical, stainless steel ball bearing by
clapping the two ball bearings together by hand in a dark room
while observing the contact to see if visible sparks are generated.
The results of the sparking test are reported in Table 11.
Example 12--Differential Scanning Calorimetry Test--Procedure Used
for Determining Exotherms in Metallic Inks
[0068] Ink compositions of Table 10 are placed in an 8 oz. glass
jar. The jar is hand shaken. The compositions are stirred slightly
using a Fischer disposable transfer pipet (Cat. 13-711-7M).
Approximately 3 ml of the ink compositions are transferred, using
the transfer pipet, to a Fischer low form fluted aluminum weighing
dish (Cat. 08-732-101), and distributed evenly therein. The
solvents in the ink compositions are allowed to evaporate overnight
at ambient temperature in a fume hood. The solid ink compositions
are scraped into 20 ml plastic vials with a micro spatula, and the
compositions are chopped up using the spatula. A small amount of
the solid ink composition, about 0.8 mg, but between 0.5 mg to 1.0
mg, is transferred to a tared TA Instruments Tzero Pan (part
#901683.901), using curved tweezers (part #271580.001). The
composition pieces are laid flat in the pan and the weight is
recorded. A Tzero Hermetic Lid (part #901684.901) is placed on the
pan. The lid is crimped onto the pan using TA Instruments Tzero
press (part #901600.901) fitted with the Tzero Hermetic die set. An
empty reference pan is also prepared in the same way. The
composition pan and reference pan are placed into the DSC Q20
instrument. The instrument is cooled to a set point of 25.degree.
C. and then the pans are loaded into the cell via the auto sampler.
They are then cooled at 10.degree. C./min. to 0.degree. C., held
for 3 min. at 0.degree. C. and then heated at 10.degree. C./min. to
250.degree. C. The process is repeated for all compositions of
Table 10.
[0069] The results are analyzed using TA Instruments Universal
Analysis 2000 software for Windows 2000/XP, version 4.4A. The
function "Integrate Peak Linear" is chosen. Two crosses appear on
the graph and are manually moved along the curve to choose the
start and end points of the exotherm. The onset temperature is
chosen where the line starts to curve up from the baseline, and the
endpoint is chosen where the line flattens out at the end of the
exotherm The magnitude of the exotherm (enthalpy as J/g) and the
onset temperature are calculated by the software and displayed on
the thermogram (DSC curve). The reported onset temperature is the
manually chosen onset point and the enthalpy (in J/g) is calculated
by the software by integrating the peak in the thermogram.
[0070] Multiple tests on a series of samples reveals a .+-.factor
of about 4% (J/g) for the exotherm enthalpy test. Note: 1
Joule=0.239 Calories; or 1 calorie=4.184 Joules.
TABLE-US-00011 TABLE 11 Results of Differential Scanning
Calorimetry (DSC) and Sparking Test Magnitude of Sparks observed on
Sample ID exotherm (J/g) impact? (yes/no) Example 1B (Inv.) Not
observed No Example 3B (Inv.) Not observed No Example 4B (Inv.) Not
observed No Example 2C (Comp.) 1639 Yes Comp. Example 3 1431 Yes
Comp. Example 4 1365 Yes Comp. Example 5 1205 Yes Inv. Example 5
1104 No Inv. Example 6 1018 No Inv. Example 7 770 No Inv. Example 8
549 No Inv. Example 9 181 No Inv. Example 10 10 No
Example 13
[0071] A metallic pigment-containing ink composition comprising
12.8 wt % metallic pigment (aluminum), 78.7 wt % solvent (41.3
ethanol, 13.5 isopropyl alcohol, 18.9 propanol, 5.0 of normal
propyl acetate), and 8.5 wt % polyvinyl butyral resin was
formulated. This ink is nitrocellulose resin-free (Owt % NC) and
its exotherm is less than 1200 J/g, and thus this is a metallic
pigment-containing ink in accordance with the present disclosure.
In press runs taking place over a period of about one (1) year,
polypropylene substrates were printed with this metallic
pigment-containing ink and with non-metallic inks of other colors
to print a graphic design. During the .about.1 year period, no
incidences of sparking, ignition, combustion, fire, or explosion
occurred. The press was a flexographic press. The press was run at
speeds of about 1600 feet per minute (ft/min).
[0072] The present invention has been described in detail,
including the preferred embodiments thereof. However, it will be
appreciated that those skilled in the art, upon consideration of
the present disclosure, may make modifications and/or improvements
on this invention that fall within the scope and spirit of the
invention.
* * * * *