U.S. patent application number 15/229557 was filed with the patent office on 2017-10-19 for solvent-uv hybrid inkjet ink for aluminum beverage can decoration.
The applicant listed for this patent is INX International Ink Co.. Invention is credited to Carlos Javier Hernandez, Robert Ramirez.
Application Number | 20170298240 15/229557 |
Document ID | / |
Family ID | 60039911 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170298240 |
Kind Code |
A1 |
Ramirez; Robert ; et
al. |
October 19, 2017 |
SOLVENT-UV HYBRID INKJET INK FOR ALUMINUM BEVERAGE CAN
DECORATION
Abstract
A hybrid inkjet ink comprising a water miscible organic solvent,
a UV radiation-curable material and appropriate photoinitiator, and
an epoxide-containing material and printed decorations produced by
applying the inkjet ink images to an aluminum substrate.
Inventors: |
Ramirez; Robert; (Castro
Valley, CA) ; Hernandez; Carlos Javier; (San Leandro,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INX International Ink Co. |
Schaumburg |
IL |
US |
|
|
Family ID: |
60039911 |
Appl. No.: |
15/229557 |
Filed: |
August 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62322007 |
Apr 13, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41M 5/0088 20130101;
C09D 11/101 20130101; B41M 5/0058 20130101; B41M 7/0081 20130101;
C09D 11/36 20130101; B41M 7/009 20130101; B41M 5/0047 20130101 |
International
Class: |
C09D 11/101 20140101
C09D011/101; B41J 2/01 20060101 B41J002/01; B41J 3/407 20060101
B41J003/407; C09D 11/36 20140101 C09D011/36 |
Claims
1. A hybrid inkjet ink comprising, in percent by weight based on
the weight of the ink: about 3-49% of a water miscible organic
solvent; about 3-80% by weight of a UV radiation-curable material
and an appropriate photoinitiator; and about 1-30% by weight of an
epoxide-containing material.
2. The hybrid inkjet ink of claim 1 in which the water miscible
organic solvent is chosen from the group consisting of carbonates,
lactones, glycols and glycol ethers.
3. The hybrid inkjet ink of claim 1 in which the organic solvent is
a lactone.
4. The hybrid inkjet ink of claim 1 in which the UV
radiation-curable material is chosen from the group consisting of:
a monofunctional UV radiation-curable monomer, a difunctional UV
radiation-curable monomer, and a trifunctional UV radiation-curable
monomer.
5. The hybrid inkjet ink of claim 4 including two or more of a
monofunctional UV radiation-curable monomer, a difunctional UV
radiation-curable monomer, and a trifunctional UV radiation-curable
monomer.
6. The hybrid inkjet ink of claim 1 in which the UV
radiation-curable material comprises all three of a monofunctional
UV radiation-curable monomer, a difunctional UV radiation-curable
monomer, and a trifunctional UV radiation-curable monomer.
7. The hybrid inkjet ink of claim 1 in which the UV
radiation-curable material monomer is a cycloaliphatic
acrylate.
8. The hybrid inkjet ink of claim 7 in which the cycloaliphatic
acrylate is isobornyl acrylate and/or
4-tert-butylcyclohexylacrylate.
9. The hybrid inkjet ink of claim 1 in which the UV
radiation-curable material is difunctional and is chosen from the
group consisting of aliphatic, cycloaliphatic, polyester,
polyurethane, and ethylene/propylene glycol diacrylates.
10. The hybrid inkjet ink of claim 9 in which the difunctional UV
radiation-curable material is hexanediol diacrylate and/or
diprophylene glycol diacrylate.
11. The hybrid inkjet ink of claim 1 in which the radiation-curable
material is propoxylated(3)trimethylopropane triacrylate.
12. The hybrid inkjet ink of claim 1 including a resin.
13. The hybrid inkjet ink of claim 12 in which the molecular weight
of the resin is less than about 100,000 Daltons.
14. The hybrid inkjet ink of claim 12 in which the molecular weight
of the resin is in the range of about 1000-50,000 Daltons.
15. The hybrid inkjet ink of claim 12 in which the resin is chosen
from the group consisting of polyols, acrylated polyesters, and
acrylated polyurethanes.
16. The hybrid inkjet ink of claim 1 in which the
epoxide-containing material is a mono-, di-, or tri-functional
epoxide chosen from the group consisting of aliphatic, aromatic,
saturated and unsaturated epoxides.
17. The hybrid inkjet ink of claim 1 in which the epoxy-containing
material comprises cyclohexyl dimethanol diglycidyl ether and/or
neopentyl glycol diglycidyl ether.
18. The hybrid inkjet ink of claim 1 including a colorant.
19. The hybrid inkjet ink of claim 18 in which the colorant is a
pigment or dye in combination with a dispersant stabilized using
dispersants that are compatible with the remaining components of
the inkjet ink.
20. A printed decoration comprising: an aluminum substrate; and an
ink composition applied to the aluminum substrate using an inkjet
printer, where the inkjet composition comprises, based upon the
total weight of the ink, about 3-49% by weight of a water miscible
organic solvent, about 3-80% by weight of a UV radiation-curable
material and an appropriate photoinitiator and about 1-30% by
weight of an epoxide-containing material.
21. A method of producing a printed decoration to an aluminum
substrate comprising: providing an aluminum substrate; providing an
inkjet ink composition comprising, based on the total weight of the
ink, about 3-49% by weight of water miscible organic solvent, about
3-80% by weight of a UV radiation-curable component, and an
appropriate photoinitiator; and about 1-30% by weight of an
epoxide-containing material; applying the inkjet composition to the
aluminum substrate using an inkjet printer to form an image on the
substrate; irradiating the image with UV light to achieve a partial
cure of the UV curable component of the ink, pinning the image to
the substrate while leaving unevaporated solvent in place within
the image; applying an overprint varnish coating to intermix with
the unevaporated solvent in the image; and heating the image to
drive off the solvent and produce a full cure of the image as a
decoration on the aluminum substrate.
22. The method of claim 21 in which the overprint varnish includes
an aqueous carrier.
23. The method of claim 21 in which the overprint varnish includes
an organic carrier.
24. The method of claim 21 in which the aluminum substrate is the
outer surface of an aluminum beverage can.
25. The hybrid inkjet ink of claim 21 in which the printed
decorations have a thickness exclusive of overprint varnish of
about 1 to 12 .mu.m.
26. The hybrid inkjet ink of claim 21 in which the printed
decorations have a thickness exclusive of overprint varnish of
about 1-8 .mu.m.
Description
FIELD
[0001] This invention pertains to solvent-UV hybrid inkjet inks
adapted for use in inkjet decoration of aluminum beverage cans, to
decorative and clear coatings produced with such inks, and to
aluminum beverage cans decorated with images applied with such
inks.
BACKGROUND
[0002] Inkjet printing is widely used for digitally applying images
to various substrates, which may be two-dimensional or
three-dimensional. Such printing is achieved using inkjet printers
having one or more printheads with nozzles for jetting the ink onto
the substrate. The printheads are typically mounted on a carriage
that moves back and forth as the substrate is advanced to receive
the ink. The printheads can also be maintained in a stationary
position and the substrate moved past the printheads.
[0003] Currently, inkjet inks are formulated either with solvent
carriers or with UV curable inks so that they can dry or cure,
respectively, by solvent evaporation or UV radiation curing.
Typically, solvent-based inkjet inks can accept high pigment
loadings and produce thinner, more flexible coatings than UV cured
inks. UV-cured inkjet inks, however, also have important
advantages, including quick curing, low VOCs, and good chemical
resistance.
[0004] The high pigment loadings achievable with solvent-based inks
are not typically achievable with UV curable inks because these
inks are inherently more viscous than solvent-based inks. Loading
these inks with the high pigment levels necessary to produce
intense and vibrant colors may make them too difficult to jet.
Therefore, when it is desirable or necessary to produce intense and
vibrant colors in inkjet printing, solvent-based inkjet inks that
tolerate high pigment loadings are typically used.
[0005] Solvent-based inkjet inks, however, do have limitations. For
example, they typically do not adhere well to nonporous substrates
like metal. Also, the final cured solvent-based inkjet ink films
typically do not have good solvent resistance.
[0006] Finding an alternative to conventional printing on aluminum
beverage cans that allows easy customization of decoration and
eliminates the need for very large print runs is highly desirable.
Conventional printing on aluminum beverage cans (e.g. offset
printing) is cumbersome since a plate must be produced for each
image and color, and so a run of at least a substantial number of
printed-cans is required by can manufacturers to recoup the plate
costs. Digital printing using inkjet technology has the potential
to revolutionize the industry since it can vary the image and color
on-demand, and has the ability do so for single cans or small print
runs.
[0007] Therefore it would be highly desirable to find a way to
decorate aluminum beverage cans using digital inkjet printers in
order to take advantage of the speed, accuracy, economy, and ready
customization of digital inkjet printing. Because of challenges
presented by current solvent-based or UV curable inkjet inks like
those noted above, this is not generally practical.
[0008] In the beverage can industry, ink performance is assessed by
successfully passing the following critical evaluation points: 1)
image resolution and quality, 2) ink cohesion with an overprint
varnish, and 3) ink adhesion to the aluminum can. This assessment
occurs throughout the can-making process, before and after heat
exposure (thermal stress), can necking (mechanical stress), and
pasteurization (chemical stress).
[0009] Currently, the two-piece metal decoration process is carried
out by first printing images on the outside of the can followed by
an immediate application of a coating on the surface of the entire
can (first piece), which is cured by baking at temperatures of
180-215.degree. C. for 3-5 minutes. After this, the can is run
through another baking step to thermally cure an inside
spray-coated epoxy film that forms a barrier between the aluminum
and beverage to protect product integrity. The cans are then
subjected to a necking process, which reduces the diameter of the
top edge of the cylindrical can down to end specifications.
[0010] During the necking procedure, the decoration and coating on
the outer surface of the can body is exposed to significant
mechanical stress and friction. Therefore application of overly
thick or non-uniform decorative coatings may lead to decoration and
coating failures. Additionally, the necked cans will also be
subjected to chemical stress by pasteurization prior to beverage
filling and lid closure (second piece of two piece can), where the
cans are submersed in 1% detergent at about 80-95.degree. C. for
10-15 minutes. Since coatings prepared using low viscosity inks
have suffered when subjected to this pasteurization step, it is
also very important to ensure that any alternative formulations are
able to withstand the stress of this chemical process.
[0011] One type of digital inkjet ink that has the potential to
meet the above requirements is acrylate-based UV curable ink. This
type of ink generally: a) has excellent weather- and light-fastness
durability, b) can be formulated at a 100% solids level to produce
good overall film hardness, and c) is highly chemically resistant
when sufficiently crosslinked. However, jettable acrylate-based UV
curable inks have not generally been adopted in the marketplace
because: 1) they produce overly thick printed images that impede
necking, and 2) adhesive and cohesive failures are often
encountered after the pasteurization step.
[0012] A solvent-based digital ink might be considered to address
the film thickness issue. This type of ink is thermally cured by
solvent evaporation, leaving behind about 12-30% solids, producing
a much thinner film. However, solvent-based inks are also rejected
in the marketplace due their poor weatherability, light-fastness,
and chemical resistance, and their high VOC content. As a result,
solvent-based digital inks produce poor image quality compared to
UV curable inks in metal can decorating applications.
[0013] Embodiments of the present invention provide unique advances
in digital printing on aluminum beverage cans using inkjet
technology. These unique embodiments successfully pass the critical
evaluation points and maintain high image quality and performance
under duress from thermal stress due to oven baking and curing,
mechanical stress due to can necking, and chemical stress due to
pasteurization, and thus comprise a very significant contribution
to the art.
SUMMARY OF THE INVENTION
[0014] Embodiments of the present invention overcome the drawbacks
of both acrylate-based UV curable and solvent-based inks by
providing jettable low viscosity inkjet inks comprising a unique
hybrid of UV-curable and solvent-based inks. These embodiments have
highly desirable properties and advantages including: a) excellent
weather- and light-fastness durability, b) ability to form thin
films that can be formulated to a range of desired thicknesses, and
c) excellent chemical resistance.
[0015] Another important characteristic of embodiments is the
ability to control step-wise cure. When the printed image is
UV-irradiated first, the resulting semi-cured film becomes immobile
(pinned), yet is still wet due to the presence of unevaporated
solvent. By applying to this semi-wet image an overprint varnish
(by, e.g., an industry conventional roller coating process),
intermixing of ink materials with overprint varnish components is
achieved. This new ink-varnish composite produces a strong cohesion
layer between the ink and varnish after the final thermal curing.
Commercially available overprint varnishes can be used. The
overprint varnish preferably will include a solvent which may be
either aqueous or organic.
[0016] Finally, strong adhesion of the ink-varnish composite to
aluminum cans may be enhanced by adding to the hybrid ink a third
component that contains an epoxide functional group. By adding an
epoxide-containing component to the hybrid ink and exposing the ink
to high temperatures, the strain energy of the epoxide cyclic
three-membered ring is released. At the molecular level, it is
believed that application of elevated temperatures during the heat
phase of the curing process is believed to catalyze the ring to
break it open and covalently bind the ink to the aluminum
surface.
[0017] Hybrid inkjet ink embodiments of the present invention
include, as necessary ingredients, about 3-49% by weight organic
solvent based on the total weight of the ink, about 3-80% by weight
of a UV radiation-curable material and an appropriate
photoinitiator based on the total weight of the ink, and about
1-30% by weight of an epoxide-containing material based on the
total weight of the ink. The organic solvent must be water miscible
and preferably is food grade for applications to beverage cans. The
organic solvent may be chosen from the group comprising of
carbonates, lactones, glycols, and glycol ethers. Among these,
lactones are currently preferred. The miscibility of the organic
solvent with water based on weight percent ratio of organic solvent
to water, should be between about 95:5 and 5:95, and preferably
between about 40:60 and 60:40.
[0018] The UV radiation curable material may be chosen from one or
more of a monofunctional UV curable monomer, a difunctional UV
curable monomer or a trifunctional UV curable monomer.
Alternatively, the UV curable component can contain two or more of
a monofunctional UV curable monomer, a difunctional UV curable
monomer or a trifunctional UV curable monomer. Finally, a mixture
of all three of a monofunctional UV curable monomer, a difunctional
UV curable monomer and a trifunctional UV curable monomer may be
used.
[0019] In embodiments, the monofunctional UV curable monomer may be
a cycloaliphatic acrylate. Preferred cycloaliphatic acrylates
include isobornyl acrylate and a most preferred cycloaliphatic
acrylate is 4-tert-butylcyclohexylacrylate.
[0020] When a difunctional UV curable monomer is used, it will act
as a crosslinker. Difunctional monomers improve the hardness and
chemical resistance of the film, as well as accelerate the rate of
polymerization. Difunctional UV curable monomers that can be used
include aliphatic, cycloaliphatic, polyester, polyurethane, and
ethylene/propylene glycol diacrylates. Hexanediol diacrylate is
preferred in embodiments and a most preferred difunctional UV
curable monomer is dipropylene glycol diacrylate.
[0021] When a trifunctional UV curable monomer is used, it will
also act as a cross-linker. One particularly preferred
trifunctional UV curable monomer is propoxylated(3)
trimethylopropane triacrylate. Trifunctional monomers provide
harder films and a faster curing response with lower UV
dosages.
[0022] The UV curable component may also contain a resin to act as
an adhesion promoter and/or to improve the hardness of the final
coating. The resin may be, for example, one or more of a polyol, an
acrylated polyester, or an acrylated polyurethane. The resin may be
UV-radiation curable or it may not be UV-radiation curable. The
molecular weights of the resin preferably will be less than about
100,000 Daltons, and most preferably will be in the range of about
1000-50,000 Daltons.
[0023] The composition will also include epoxy functional modifiers
and photoinitiators that act as polymerization initiators.
[0024] The epoxide containing material will be a mono-, di-, or
tri-functional epoxide chosen from the group comprising aliphatic,
aromatic, saturated and unsaturated epoxides. Among these,
aliphatic epoxides are currently preferred. As explained earlier,
the epoxide containing material is believed to act as cross-linkers
and to improve the adhesion to metal oxide surfaces, such as the
aluminum oxide found in the surface of aluminum cans. The epoxy
containing material may comprise mono- or di-epoxy containing
monomers. Preferred epoxy functional modifiers include cyclohexyl
dimethanol diglycidyl ether. A particularly preferred epoxy
functional modifier is neopentyl glycol diglycidyl ether.
[0025] While the inkjet ink composition may be used as a
colorant-free clear coating or varnish, in most applications it
will include a colorant, which can be pretreated so that it is
self-dispersing or it may include a colorant in the form of a
pigment or dye in combination with a separate dispersant. In the
latter case the colorant will be stabilized using appropriate
dispersants that are compatible with the UV curable component, the
epoxy functional modifier, and the solvent. One measure of
compatibility is that the combined components in the ink must be
stable at elevated temperatures, broadly from about 20-80.degree.
C. for four weeks, and preferably from about 20-60.degree. C. for
two weeks.
[0026] In embodiments of the invention, a dispersant is preferably
added not only to improve the dispersibility of the colorant (when
needed) but also to improve the storage stability of the ink.
Examples of dispersants that can be used include hydroxyl
group-containing carboxylate esters, salts of long-chain
polyaminoamides and esters of high molecular weight acids, salts of
high molecular weight polycarboxylic acids, salts of long-chain
polyaminoamides and esters of polar acids, esters of high molecular
weight unsaturated acids, high molecular weight copolymers,
modified polyurethanes, modified polyacrylates,
polyetherester-based anionic surfactants, salts of
naphthalenesulfonic acid-formalin con-densation products, salts of
aromatic sulfonic acid-formalin condensation products,
polyoxyethylene alkylphosphate esters, polyoxyethylene nonylphenyl
ether, and stearylamine acetate.
[0027] Specific examples of suitable dispersants include
"Anti-Terra-U (a polyaminoamide phosphate)", "Anti-Terra-203/204
(salts of high molecular weight polycarboxylic acids)", "Disperbyk-
101 (a phosphate salt ofa polyaminoamide and an acid ester), 107 (a
hydroxyl group-containing carboxylate ester), 110 and 111
(copolymers that contain acid groups), 130 (a polya-25 mide),
161,162, 163,164, 165, 166 and 170 (high molecular weight
copolymers)", "Bykumen (an ester of a high molecular weight
unsaturated acid)", "BYK-P104, P105 (high molecular weight
unsaturated polycarboxylic acids", "P104S, 240S (systems containing
a high molecular weight unsaturated polycarboxylic acid and
silicon)", and "Lactimon (a combination of a long-chain amine, an
unsaturated polycarboxylic acid, and silicon)". These products are
available from BYK Chemie. Other suitable dispersants include "Efka
44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71,701, 764 and 766", "Efka
Polymer 100 (a modified polyacrylate), 150 (an aliphatic modified
polymer), 400, 401,402,403,450, 451,452 and 453 (modified
polyacrylates), and 745 (a copper phthalocyanine system)" (Efka
Chemicals), include "Florene TG-710 (a urethane oligomer)",
"Flonone SH-290 and SP-1000", and 40 "Polyflow No. 50E and No. 300
(acrylic copolymers)"; and products manufactured by Kusumoto
Chemicals Ltd. include "Disparlon KS-860, 873 SN and 874 (high
molecular weight dispersants), #2150 (an aliphatic polyvalent
carboxylic acid), and #7004 (a polyether ester)" (Kyoeisha Chemical
Co., Ltd.)
[0028] Still other suitable dispersants include "Demol RN and N
(sodium salts of naphthalene- sulfonic acid-formalin condensates),
MS, C and SN-B (sodium salts of aromatic sulfonic acid-formalin
condensates), and EP", "Homogenol L-18 (a polycarboxylic acid type
polymer)", "Emalgen 920, 930, 931,935,950 and 985 (polyoxy-
ethylene nonylphenyl ethers)", and "Acetamine 24 (a coconut amine
acetate) and 86 (stearylamine acetate)" (Kao Corporation)
"Solsperse 5000 (a phthalocyanine ammonium salt system), 13940 (a
polyes-teramine system), 17000 (a fatty acid amine system), and
24000" (Avecia Ltd.) "Nikol T106 (a polyoxyethylene sorbitan
monooleate) and MYS-IEX (a polyoxyethylene monostearate), and
Hexagline 4-0 (a hexaglyceryl tetraoleate)" (Nikko Chemicals Co.,
Ltd.) "Ajisper PB821 and PB822 (basic dispersants)". The quantity
of the dispersant within the ink preferably represents from 0.1 to
10% by weight of the total weight of the ink (Ajinomoto-Fine-Techno
Co., Inc.).
[0029] In embodiments the inkjet ink composition will also include
conventional ingredients like colorants, photosensitizers,
photosynergists, stabilizers and surfactants.
[0030] Examples of surfactants that can be used include
fluorosurfactants, anionic surfactants such as sodium
dodecylbenzenesulfonate, sodium laurate, and ammonium salts of
polyoxyethylene alkyl ether sulfate; and nonionic surfactants such
as polyoxy-ethylene alkyl ethers, polyoxyethylene alkyl esters,
polyoxy-25 ethylene sorbitan fatty acid esters, polyoxyethylene
alkylphenyl ethers, polyoxyethylene alkylamines, and
polyoxyethylene alkylamides. Other examples of surfactants that can
be used include polyoxyalkylene polyalkylene amines and sorbitan
esters. Examples of polyoxyalkylene polyalkylene polyamines,
include Discole N-503, N-506, N-509, N-512, N-515, N-518, and
N-520. (Dainichiseika Coln and Chemicals Mfg. Co.)
[0031] Printed decorations prepared using the inkjet composition of
embodiments (exclusive of overprint varnish) will have a film
thickness of about 1 to 12 .mu.m, preferably about 1-10 .mu.m and
most preferably about 1-8 .mu.m. These ink thicknesses enable the
coating to successfully withstand mechanical stress put on the can
container by the necking machinery.
[0032] The coatings, in their final cured state (printed decoration
and overprint varnish) will have a pencil hardness between 3B to
9H, and preferably between 2B to 9H.
[0033] In embodiments an overprint varnish will be applied to
coatings prepared using the inkjet printing compositions. Overprint
varnishes are used to help protect ink coatings. However, in
embodiments herein, the level of protection and enhanced image
quality achieved by intermixing the overprint varnish and the
hybrid ink embodiments is outstanding.
[0034] In further embodiments, processes to produce decorative
coatings in accordance with embodiments will entail: A) application
of the inkjet composition using an inkjet printer followed by UV
irradiation to achieve a partial cure; B) application of the
overprint coating and, C) final heating to produce full cure. As
noted earlier, in this wet-on-wet embodiment the UV curable
component is initially pinned by applying UV radiation to cure
(polymerize) that component, leaving the unevaporated solvent of
the hybrid ink in place and an interim coating in the form of a
"semi-wet print". When the overprint coating is applied to the
"semi-wet print" it intermixes with the water miscible solvent
component before the final heating step. While heating times and
temperatures may vary depending on system parameters, the heating
following the initial application may be carried out in an oven,
for example, at about 80-350.degree. C. for about 1-40 minutes, and
most preferably about 180-215.degree. C. for about 3-5 minutes.
[0035] While the inventors do not intend to limit the invention to
any theoretical mechanisms or pathways, it is believed that the
outstanding adhesion image quality, glossiness and other properties
achieved may be obtained when the aluminum oxide passivation layer
formed on the surface of the can container during the heating step
reacts with the oxygen in the epoxide group of the
epoxide-containing component to initiate reaction with other
components in the ink composition. Another non-limiting possible
explanation may be that the Al.sup.3- ion species on the surface of
the can is coordinated by the epoxide oxygen, catalyzing a
ring-opening and reaction with other components of the ink.
EXAMPLES
[0036] The following examples are presented for purposes of
illustration and are not intended to be exhaustive or limiting of
any embodiment of the invention.
[0037] 1. Adhesion to Aluminum Substrate
[0038] The test specimens were successfully necked cans with
inkjet-applied decoration and an overprint varnish top coat. An
ASTM standard test method D3359-09 was used to measure and examine
the adhesion of inkjet-applied hybrid ink. A hard metal straight
edge was used to make straight cuts with a sharp razor blade to
form intersecting 7 to 8 crosshatched cuts in selected areas of the
body and neck of the cans. The tape applied was a 0.75'' wide
transparent Scotch.RTM. Brand Tape, Cat 600.
[0039] The crosshatch adhesion tests on both the necked areas of
the can specimens and on the bodies of the can specimens for CMYK
image hybrid coatings did not show any adhesion failure and had
outstanding adhesion ratings of 4B- 5B, before and after
pasteurization.
[0040] 2. Gloss Level
[0041] An ASTM standard test method D523-08 was used to measure the
specular gloss of nonmetallic specimens for glossmeter geometries
of 20, 60, and 85.degree. using two specimens: 1) a hybrid black
ink prepared in accordance with embodiments of the invention and
applied using an inkjet printer, and 2) a commercial black beverage
can coating prepared using conventional offset printing. A black
hybrid inkjet ink as follows was used:
TABLE-US-00001 Material Type Percent by Weight
4-tert-butylcyclohexyl acrylate (monomer) 13 2-phenoxyethyl
acrylate (monomer) 4 Propoxylated (3) Trimethylopropane Triacrylate
6 (trifunctional monomer) Resin 12 Amine Synergist 8 Antioxidant
and thermal stabilizer blend 1 Surfactant 1 Photoinitiator Norrish
Type I 3.5 Photoinitiator Norrish Type II 3.5 Black Pigment
Dispersion (colorant) 15 Gamma-butyrolactone (solvent) 20 Neopentyl
glycol diglycidyl ether (epoxide) 13 100
[0042] The 20.degree. geometry is advantageous for comparing
specimens having 60.degree. gloss values higher than 70. The
60.degree. geometry is used for inter-comparing most specimens and
for determining when the 20.degree. geometry may be more
applicable. The 85.degree. geometry is used for comparing specimens
for sheen or near-grazing shininess; it is most frequently applied
when specimens have 60.degree. gloss values lower than 10.
[0043] The following results were obtained:
TABLE-US-00002 Gloss Level Commercial Hybrid Angle Black Black
20.degree. 57.6 66.7 60.degree. 87.4 89.9 85.degree. 96.6 94.4
[0044] This data demonstrates that the hybrid inkjet black ink
coating can produce gloss levels commensurate with those achieved
using conventional offset printing processes. In other words, the
new hybrid ink is shown here to enable inkjet printing on aluminum
cans to produce gloss levels commensurate with those achieved in
conventional offset printing processes thereby delivering all of
the benefits of inkjet printing to the can printing process.
* * * * *