U.S. patent application number 11/109479 was filed with the patent office on 2005-11-24 for radiation-curable high gloss overprint varnish compositions.
Invention is credited to Gould, Michael L., Narayan-Sarathy, Sridevi.
Application Number | 20050261391 11/109479 |
Document ID | / |
Family ID | 35242125 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050261391 |
Kind Code |
A1 |
Narayan-Sarathy, Sridevi ;
et al. |
November 24, 2005 |
Radiation-curable high gloss overprint varnish compositions
Abstract
The present invention relates to radiation-curable overprint
varnishes for printed substrates based on multifunctional,
uncrosslinked, liquid Michael addition resins. The compositions are
UV-curable with little or no photoinitiator present.
Inventors: |
Narayan-Sarathy, Sridevi;
(Dublin, OH) ; Gould, Michael L.; (Powell,
OH) |
Correspondence
Address: |
Martin Connaughton
Ashland Inc.
P.O. Box 2219
Columbus
OH
43216
US
|
Family ID: |
35242125 |
Appl. No.: |
11/109479 |
Filed: |
April 19, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60564025 |
Apr 21, 2004 |
|
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Current U.S.
Class: |
522/173 |
Current CPC
Class: |
C09D 151/003 20130101;
C09D 175/16 20130101; C09D 151/08 20130101; C09D 151/08 20130101;
C08F 290/06 20130101; C08G 18/672 20130101; C08F 290/061 20130101;
C08F 289/00 20130101; C08F 265/04 20130101; C08L 2666/04 20130101;
C08L 2666/02 20130101; C08L 2666/02 20130101; C08L 33/08 20130101;
C08G 18/3215 20130101; C08F 265/06 20130101; C08F 283/01 20130101;
C09D 133/08 20130101; C09D 151/003 20130101; Y10T 428/31855
20150401; C09D 133/08 20130101 |
Class at
Publication: |
522/173 |
International
Class: |
C08G 002/00 |
Claims
We claim:
1. A high gloss, UV curable overprint varnish composition,
comprising; A. a liquid michael addition resin present in amounts
up to 99 wt. % based on the total weight of the overprint varnish
composition, comprising the uncrosslinked reaction product of, i. a
michael donor, and ii. a michael acceptor and B. at least one of
the following, i. a diluent, ii. a photoinitiator, iii. an adhesion
promoter, iv. a defoaming agent, v. a flow and leveling aid, and
vi. an amine synergist, wherein the high gloss overprint varnish
composition has a viscosity of less than about 500 centipoise:
2. The composition of claim 1, wherein the Michael donor is a
.beta.-dicarbonyl compound.
3. The composition of claim 1, wherein the Michael acceptor is an
acrylate monomer, oligomer, polymer or mixture thereof.
4. The composition of claim 1, wherein the Michael donor is
selected from the group consisting of a .beta.-ketoester, a
.beta.-diketone, a .beta.-ketoamide, a .beta.-ketoanilide and
mixtures thereof.
5. The composition of claim 1, wherein the Michael acceptor is
selected from the group consisting of monoacrylates, diacrylates,
triacrylates, tetraacrylates and mixtures thereof.
6. The composition of claim 1, wherein the Michael addition resin
is modified to contain a pendant Type I photoactive and/or Type II
photoactive moiety.
7. The composition of claim 1, wherein the Michael donor is
modified to contain a pendant Type I photoactive and/or Type II
photoactive moiety.
8. The composition of claim 1, wherein the Michael acceptor is
modified to contain a pendant Type I photoactive and/or Type II
photoactive moiety.
9. The composition of claim 1, wherein the Michael addition resin
is present in an amount from about 60 wt % to about 98 wt %.
10. The composition of claim 1, wherein the Michael addition resin
is present in an amount from about 80 wt % to about 98 wt %.
11. The composition of claim 1, containing an adhesion
promoter.
12. The composition of claim 1, containing a reactive diluent.
13. The composition of claim 1, containing a reactive diluent, a
photoinitiator, an amine synergist and a flow and leveling aid.
14. The composition of claim 1, containing a reactive diluent, a
defoaming agent and a flow and leveling aid.
15. The composition of claim 1, containing a reactive diluent, an
amine synergist and a photoinitiator.
16. A coated article, comprising A. a substrate having at least one
printed surface, and B. a high gloss overprint varnish on at least
one printed surface of the substrate, comprising the cured,
cross-linked reaction product of a liquid Michael addition resin,
comprising: i. a Michael donor, and ii. a Michael acceptor, wherein
the crosslinked reaction product has a gloss of at least 60.
17. The coated article of claim 16, wherein the Michael addition
resin has a gloss of at least 80.
18. The coated article of claim 16, further comprising one or more,
A. diluent, B. photoinitiator, C. adhesion promoter, D. defoaming
agent, E. flow and leveling aid, or F. amine synergist.
19. The coated article of claim 16, wherein the Michael addition
resin is modified to contain a pendant Type I photoactive and/or
Type II photoactive moiety.
20. The coated article of claim 16, wherein the Michael donor is
modified to contain a pendant Type I photoactive and/or Type II
photoactive moiety.
21. The coated article of claim 16, wherein the Michael acceptor is
modified to contain a pendant Type I photoactive and/or Type II
photoactive moiety.
22. The coated article of claim 16, wherein the Michael donor is
selected from the group consisting of a .beta.-ketoester, a
.beta.-diketone, a .beta.-ketoamide, a .beta.-ketoanilide and
mixtures thereof.
23. The coated article of claim 16, wherein the Michael acceptor is
selected from the group consisting of monoacrylates, diacrylates,
triacrylates, tetraacrylates and mixtures thereof.
24. The coated article of claim 16, wherein the Michael addition
resin is cured via exposure to actinic radiation.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of the
provisional application Ser. No. 60/564,025, filed Apr. 21,
2004.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to radiation curable overprint
varnishes (OPV). The overprint varnishes are based on
multifunctional, uncrosslinked, liquid Michael addition resins
formed from the reaction of acrylate monomers, known as Michael
addition reaction acceptors (hereinafter "Michael acceptors") and
.beta.-ketoesters (e.g., ethyl acetoacetate), .beta.-diketones
(e.g., 2,4-pentanedione), and/or .beta.-keto amides (e.g.,
acetoacetanilide, acetoacetamide), or other .beta.-dicarbonyl
compounds and mixtures thereof, known as Michael addition reaction
donors (hereinafter "Michael donors") that can participate in the
Michael addition reaction. The OPV formulations based on the above
multifunctional, uncrosslinked, liquid Michael addition resins can
be cured under standard UV cure conditions with no photoinitiator
or substantially less photoinitiator than is currently used in
UV-curable OPV compositions.
[0003] UV-curable OPVs are known. Typically, UV-curable overprint
varnish coatings comprise a composition capable of curing when
exposed to UV radiation such as an acrylate monomer, oligomer or
polymer in the presence of a photoinitiator of some sort. In
addition to the curable component, the OPVs contain various
additives to modify and improve the performance of the cured
coating. Examples of OPVs include the composition disclosed in U.S.
Pat. Nos. 4,204,010, 4,227,979 and published US application
20020121631. U.S. Pat. No. 4,204,010 discloses an ethylenically
unsaturated reactive thixotropic agent for use in radiation-curable
overprint varnishes formed by reacting a hydroxyl-containing fatty
acid ester with an ethylenically unsaturated isocyanate. The
composition generally contains a photoinitiating component such as
benzophenone. U.S. Pat. No. 4,227,979 discloses UV-curable OPVs
containing an amine acrylate and various photo-promoters. Published
US application 20020121631 discloses UV-curable OPV compositions
that generally include di- and trifunctional acrylate monomer, a
photoinitiator, an acrylated oligomer and an acrylic polymer
emulsion.
[0004] Overprint varnishes are used to produce cured coatings that
provide both a protective layer and embellished feel or appearance
to printed materials. High quality overprint varnish coatings can
give improved rub and scuff resistance and the lower coefficients
of friction necessary for use in high speed packaging lines. OPVs
can also be used to improve the appearance of conventional solvent
and water-based inks which are often characterized by low gloss.
Special finishes can be built into OPVs by using suitable
additives. For example, pearlescent effects can be achieved by
using specialized mica-based pearlescent pigments. Fluorescent and
optical brightening additives can also be added. There is a wide
scope for specialized finishes made possible by using such
additives to enhance the final cured product.
[0005] The mode of application of OPVs is dependent on the final
viscosity of the uncrosslinked liquid formulation. Low viscosity
formulations are typically applied using flexographic, gravure,
roll-coater, and flood or curtain-coater equipment. Historically,
varnishing was often carried out separately from printing. Today,
many new printing presses have in-line varnish coaters fitted after
the printing units. For application over UV-based inks, some
presses are fitted with interdeck and pre-coater UV lamps to ensure
that the inks are cured before the varnish is applied, thus
achieving a smooth lay-down and high gloss.
[0006] Typical starting point formulations for standard UV-curable
OPVs contain up to 10 parts per hundred (10% w/w) of a
photoinitiator package. Traditional photoinitiators (e.g.,
benzophenone) can be toxic, expensive, and malodorous and
contribute to film color, which limits applicability of varnishes
over white and light-colored inks.
[0007] The amount of photoinitiator added to OPV formulations can
be significantly reduced by using the acrylate oligomer technology
described in patents U.S. Pat. No. 5,945,489 and U.S. Pat. No.
6,025,410 (both Ashland, Inc.) the contents of which are
incorporated herein by reference. These patents disclose
uncrosslinked resins prepared via the Michael addition reaction of
Michael donors such as .beta.-dicarbonyl compounds with Michael
acceptors such as multifunctional acrylates. The invention
disclosed herein demonstrates the advantageous use of these
uncrosslinked resins alone or modified by reaction/blending with
additional materials in formulations for overprint varnish
applications. These additional materials include a variety of
reactive diluents and adhesion promoting acrylic monomers and
oligomers as well as other vinyl monomers like N-vinyl caprolactam,
primary, secondary and tertiary amines, acid-functional materials,
siloxane-based defoamers, wetting agents, flow and leveling aids,
elastomers, waxes and other components to modify and improve
performance of the varnish.
[0008] Varnishes based on the resins described above can be cured
by all methods typically used to crosslink acrylic materials. Cure,
or crosslinking, is usually accomplished through a free radical
chain mechanism, which may require any of a number of free
radical-generating species such as peroxides, hydroperoxides, REDOX
combinations, etc., which decompose to form radicals when heated,
or at ambient temperature in the presence of amines and transition
metal promoters. Ultra violet (UV) radiation is another means of
initiating reaction by decomposing an appropriate photoinitiator to
form free radicals. Electron beam (EB) radiation can also be used
to effect cure.
[0009] OPVs based on the novel acrylate oligomers described in this
invention offer significant advantages over varnishes based on
traditional multifunctional acrylic monomers and oligomers in that
they can be cured by exposure to UV radiation with no
photoinitiator or a fraction of the photoinitiator required for
standard UV-cure varnishes. Under typical UV curing conditions for
OPVs (<300 mJ/cm.sup.2 exposure), these varnishes can be
effectively cured on a variety of substrates with very little or no
photoinitiator.
[0010] The novel OPV formulations disclosed here exhibit
performance properties that make them very effective across a range
of substrates and these properties can be modified greatly
depending upon oligomer composition and coating formulation rather
than by blending with additives, as is done in traditional
UV-curable systems. The varnishes can exhibit wide ranges of
flexibility, stain resistance, scratch resistance, weather
resistance, solvent resistance, etc. Almost any desired varnish
performance parameter can be attained by proper selection of the
raw material building blocks used to make the oligomers that form
the basis of the OPV formulation.
SUMMARY OF THE INVENTION
[0011] The invention detailed herein comprises a family of
radiation-curable, high gloss OPV compositions. These OPVs are
based on multifunctional acrylate resins formed by the reaction of
Michael acceptors such as acrylate monomers and oligomers with
Michael donors such as .beta.-keto esters (e.g., acetoacetates),
.beta.-diketones (e.g., 2,4-pentanedione), .beta.-keto amides
(e.g., acetoacetanilide, acetoacetamide), and/or other
.beta.-dicarbonyl or other compounds that can participate in the
Michael addition reaction. An essential novelty of these OPV
formulations is that they will cure under standard UV-cure
conditions with very little or no traditional photoinitiator as
compared to commercial formulations which require the addition of
substantial photoinitiator.
[0012] The multi-functional polyacrylate oligomers, from which the
varnishes of the present invention are formulated, have dual
chemical functionality. That is, they have both acrylic
functionality and a labile ketone group that is capable of
dissociating to initiate free radical polymerization of the
oligomer upon exposure to UV radiation. Final OPV properties can be
modified in a number of ways including use of additional or
supplementary acrylate materials, using any number of different
.beta.-dicarbonyl compounds, or simply varying the stoichiometry of
the reactants which comprise the oligomer. Varnishes can be made
softer and more flexible with less shrinkage and significantly
better adhesion to a variety of substrates. OPVs based on the novel
multifunctional acrylate resins of the present invention exhibit
excellent gloss, adhesion, flexibility, solvent resistance, scratch
resistance, and durability. These coatings may be cured via
chemical means, thermally, or by exposure to UV or electron beam
radiation.
[0013] Other materials, both reactive (conventional acrylates) and
non-reactive (e.g., solvents) may also be incorporated into
formulations to enhance the varnish properties on various
substrates. These additives include a variety of acrylic monomers
and oligomers, other vinyl monomers like N-vinyl caprolactam,
primary, secondary, and tertiary amines, acid-functional monomers
and oligomers, defoamers, wetting agents, flow and leveling aids,
silicones, waxes and elastomers, among others.
[0014] Systems comprised of traditional monomers and oligomers
often have compatibility issues with some of the above additives,
making for less formulating options. However, formulations built
from the novel photocurable oligomer resins described herein can
incorporate a nearly unlimited variety of additives due to the
chemical/architectural control possible in their synthesis. Thus,
many more options are available to the formulator who must address
specific challenges (e.g., adhesion, flexibility, etc.) for each
particular substrate.
BRIEF DESCRIPTION OF THE FIGURES
[0015] FIG. 1 depicts the preparation of a Michael donor with a
built-in Type I photoinitiator and two Michael acceptors with a
built-in Type I photoinitiator.
[0016] FIG. 2 depicts the use of built-in photoinitiator-modified
Michael donor in the formation of a Michael addition resin and its
cure via exposure to UV radiation.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The invention relates to a radiation curable glossy
overprint varnish. The high gloss overprint varnish compositions
are comprised of a liquid, Michael addition resin comprising the
uncrosslinked reaction product of a Michael donor and a Michael
acceptor, and at least one of a number of components such as a
diluent, a photoinitiator, an adhesion promoter, a defoaming agent,
a flow and leveling agent, an amine synergist and other components
typically used in glossy overprint varnish formulations. The OPV
compositions of the present invention can be modified for use on
any number of substrates, examples of which include coated paper,
board-stock, PET and BOPP (bi-axially oriented polypropylene). The
liquid, uncrosslinked, Michael addition resin is comprised of a
Michael donor and a Michael acceptor. The Michael addition resin is
present in amounts up to 99 wt. %, preferably from about 60 wt. %
to about 98 wt %, more preferably from about 80 wt. % to about 98
wt. % based on the total weight of the OPV composition.
[0018] The Michael addition resin can be modified to enhance
performance in a variety of ways, examples of which include
incorporating an amine synergist for improved surface cure, a
silicone for built-in "slip" modification and/or building in a
conventional photoinitiator.
[0019] The liquid, uncured Michael addition resin is a polyacrylate
oligomer formed from a multifunctional acrylate Michael acceptor
and a .beta.-dicarbonyl Michael donor. This technology is described
in U.S. Pat. Nos. 5,945,489 and 6,025,410, both assigned to Ashland
Inc. and the entire contents of which are incorporated by
reference.
[0020] The .beta.-dicarbonyl Michael donor is suitably chosen from
among .beta.-keto esters, .beta.-diketones, .beta.-ketoamides, and
.beta.-ketoanilides. The multifunctional acrylate Michael acceptor
is suitably chosen from among diacrylates, triacrylates,
tetraacrylates and the like. A range of .beta.-dicarbonyl donors
and multifunctional acrylate acceptors affords the composition
designer the opportunity to exercise a great range of selectivity
in the properties of the final product.
[0021] A small amount of mono-functional acrylate can be
incorporated along with the multifunctional acrylates to modify the
product oligomers, for instance, to enhance adhesion, toughness or
other characteristics of the final Michael adduct. Monoacrylates
include, but are not limited to: 2-phenoxyethyl acrylate (PEA)
and/or higher order alkoxylated products, isobornyl acrylate,
tetrahydrofurfuryl acrylate (THFFA), glycidyl acrylate, dodecyl
acrylate, phenylthioethyl acrylate, acrylate-functional
polysiloxanes, perfluoroalkyl ethyl acrylate esters and mixtures
thereof. Preferably the mono-functional acrylate is present in
amounts up to 20 wt %, more preferably up to 10 wt % based on the
total weight of the Michael addition resin.
[0022] Diacrylates include, but are not limited to: ethylene glycol
diacrylate, propylene glycol diacrylate, diethylene glycol
diacrylate, dipropylene glycol diacrylate, triethylene glycol
diacrylate, tripropylene glycol diacrylate, tertraethylene glycol
diacrylate, tetrapropylene glycol diacrylate, polyethylene glycol
diacrylate, polypropylene glycol diacrylate, ethoxylated bisphenol
A diacrylate, bisphenol A diglycidyl ether diacrylate, resorcinol
diglycidyl ether diacrylate, 1,3-propanediol diacrylate,
1,4-butanediol diacrylate, 1,5-pentanediol diacrylate,
1,6-hexanediol diacrylate, neopentyl glycol diacrylate, cyclohexane
dimethanol diacrylate, ethoxylated neopentyl glycol diacrylate,
propoxylated neopentyl glycol diacrylate, ethoxylated
cyclohexanedimethanol diacrylate, propoxylated
cyclohexanedimethanol diacrylate, thiodiglycol diacrylate,
acrylate-functional polysiloxane, epoxy diacrylate, aryl urethane
diacrylate, aliphatic urethane diacrylate, polyester diacrylate,
and mixtures thereof.
[0023] Triacrylates include, but are not limited to: trimethylol
propane triacrylate, glycerol triacrylate, ethoxylated
trimethylolpropane triacrylate, propoxylated trimethylolpropane
triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate,
ethoxylated glycerol triacrylate, propoxylated glycerol
triacrylate, pentaerythritol triacrylate, aryl urethane
triacrylates, aliphatic urethane triacrylates, melamine
triacrylates, epoxy novolac triacrylates, aliphatic epoxy
triacrylate, polyester triacrylate, acrylate-functional
polysiloxanes and mixtures thereof.
[0024] Tetraacrylates include, but are not limited to:
di-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate,
ethoxylated pentaerythritol tetraacrylate, propoxylated
pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate,
ethoxylated dipentaerythritol tetraacrylate, propoxylated
dipentaerythritol tetraacrylate, aryl urethane tetraacrylates,
aliphatic urethane tetraacrylates, polyester tetraacrylates,
melamine tetraacrylates, epoxy novolac tetraacrylates,
acrylate-functional polysiloxanes and mixtures thereof.
[0025] The present invention can be practiced with a
.beta.-ketoester (e.g., ethyl acetoacetate), a .beta.-diketone
(e.g., 2,4-pentanedione), a .beta.-ketoanilide (e.g.,
acetoacetanilide), a .beta.-ketoamide (e.g., acetoacetamide) or a
mixture of Michael donors according to the desired resin
quality.
[0026] Suitable .beta.-dicarbonyl donor compounds having
functionality of 2 include, but are not limited to: ethyl
acetoacetate (EM), methyl acetoacetate, 2-ethylhexyl acetoacetate,
lauryl acetoacetate, t-butyl acetoacetate, acetoacetanilide,
N-alkyl acetoacetanilide, acetoacetamide, 2-acetoacetoxylethyl
acrylate, 2-acetoacetoxylethyl methacrylate, allyl acetoacetate,
benzyl acetoacetate, 2,4-pentanedione, isobutyl acetoacetate, and
2-methoxyethyl acetoacetate.
[0027] Suitable .beta.-dicarbonyl donor compounds having
functionality of 4 include, but are not limited to: 1,4-butanediol
diacetoacetate, 1,6-hexanediol diacetoacetate, neopentyl glycol
diacetoacetate, cyclohexane dimethanol diacetoacetate, and
ethoxylated bisphenol A diacetoacetate.
[0028] Suitable .beta.-dicarbonyl donor compounds having
functionality of 6 include, but are not limited to: trimethylol
propane triacetoacetate, glycerin triacetoacetate, and
polycaprolactone triacetoacetates.
[0029] The Michael addition reaction is catalyzed by a strong base.
An example of such a base is diazabicycloundecene (DBU), which is
sufficiently strong and is readily soluble in the monomer mixtures.
Other cyclic amidines, for example diazabicyclo-nonene (DBN) and
guanidines are also suitable for catalyzing this reaction. Group I
alkoxide bases such as potassium tert-butoxide, provided they have
sufficient solubility in the reaction medium, are also typically
adequate to promote the desired reaction. Quaternary hydroxides and
alkoxides, such as tetrabutyl ammonium hydroxide or benzyltrimethyl
ammonium methoxide, comprise another class of base catalysts that
promote the Michael addition reaction. Finally, strong,
organophilic alkoxide bases can be generated in situ from the
reaction between a halide anion (e.g., quaternary halide) and an
epoxide moiety. Such in situ catalysts are disclosed in U.S. Pat.
No. 6,706,414 assigned to Ashland, Inc. the entire contents of
which are incorporated by reference.
[0030] The Michael addition resins can also be modified to include
built in photoactive moieties based on conventional
photoinitiators. In this case the .beta.-dicarbonyl Michael donor
and/or Michael acceptors are modified to contain pendant Type I
(e.g., substituted benzoins, benzyl ketals, acetophenones or acyl
phosphine oxides) or Type II (e.g., substituted benzophenones,
thioxanthones, camphorquinones or bisimidazoles) photoactive
moieties. The resulting liquid, uncrosslinked Michael addition
resins possess either or both Type I and Type II photoactive
functional groups that promote the addition polymerization of
acrylic groups upon exposure to UV light. Examples of modified
Michael donors and acceptors are shown in FIG. 1. An example of a
cured network using a Type I photoactive moiety-modified
acetoacetic Michael donor and TMPTA is shown in FIG. 2. Other
examples of Michael addition adducts modified with built in
photoinitiators are disclosed in the co-pending provisional
application titled, "Radiation Curable Michael Addition Resins
Having Built-in Photoinitiators", filed Apr. 21, 2004, having a
U.S. Ser. No. 60/564026, the entire contents of which are
specifically incorporated by reference in its entirety.
[0031] The Michael addition resins used in the OPV compositions can
also be modified to enhance performance by adding an amine
synergist. An example of such a modification includes incorporating
primary or secondary amines into the uncured Michael addition
resin. This technique is disclosed in U.S. Pat. No. 6,673,851 the
teachings of which are incorporated herein by reference. Typical
primary amines include ethanolamine, methyl-1,6-hexanediamine,
3-aminopropyltrimethoxysilane, diaminopropane, benzyl amine,
triethylenetetraamine, isophorone diamine and mixtures thereof.
Typical secondary amines include dimethylamine, dibutyl amine,
diethanolamine (DEA), piperidine, morpholine and mixtures thereof.
If the liquid Michael addition resin is modified with a primary or
secondary amine, the modifying amine is simply reacted with the
liquid, uncured, Michael addition resin. Tertiary amines can also
be used as a synergist however they do not react with the resin via
the pseudo Michael addition reaction as do the primary and
secondary amines. Tertiary amines are considered non-reactive amine
synergists in this modification paradigm. An example of a useful
tertiary amine includes methyl diethanolamine (MDEA).
[0032] Diluents can also be present in the high gloss OPV
compositions of the present invention. The diluents include
reactive diluents such as trimethylol propane triacrylate (TMPTA),
alkoxylated TMPTA, and other acrylate monomers, and although not
preferred, non-reactive diluents include known solvents, such as
acetone and/or plasticizers. The diluents are used to modify the
viscosity of the OPV composition and in the case of acrylate
monomers, participate in the final cure. Diluents can be present in
amounts up to 40 wt. %. Adhesion promoting compounds can also be
present in the OPV compositions. Examples of adhesion promoting
compounds include N-vinyl caprolactam, N-vinyl pyrrolidone, N-vinyl
morpholine, acryloyl morpholine, vinyl ether esters,
acid-functional acrylic monomers such as .beta.-carboxyethyl
acrylate or phosphoric acid acrylates, tetrahydrofurfuryl acrylate
and phenoxy ethyl acrylate. Adhesion promoters can be present in
amounts up to 40 wt. %.
[0033] Defoamers, both reactive and non-reactive in amounts up to 4
wt. % can be used in the present invention. Examples of suitable
reactive defoaming agents such as L-37 and LG-99 are available
commercially from Estron Chemicals. Examples of suitable
non-reactive defoamers include silicone defoamers such as BYK 019
available commercially from BYK Chemie or TegoRad from Degussa.
[0034] Photoinitiators can be used in the present OPV compositions
but in significantly reduced amounts when compared to known
UV-curable OPV compositions.
[0035] Typical levels for photoinitiators in conventional OPV
formulations can be 10 wt. %. Photoinitiators used in the OPVs of
the present invention are present in amounts from 0 to 5 wt. %,
more preferably from 0 to 4 wt %. Examples of suitable
photoinitiators include those known in the art such as benzoin,
benzoin methyl ether, 2-benzyl-2-dimethylamino-1-
-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexyl phenyl
ketone, benzophenone, 4-phenyl benzophenone, acetophenone, and the
like.
[0036] Flow/leveling agents in amounts up to 4 wt. % can be used in
the present OPV compositions. Examples of flow and leveling aids
include polydimethylsiloxane polymers, fluorinated oligomers and
the like.
[0037] The novel OPV compositions disclosed herein exhibit
performance properties that make them very effective across a range
of substrates and these properties can be modified greatly
depending upon oligomer composition and coating formulation rather
than by blending with additives, as is done in traditional UV OPV
systems. The varnishes can exhibit wide ranges of flexibility,
stain, scratch, weather and solvent resistance, and adherence to
substrates. Almost any desired varnish performance parameter can be
attained by proper selection of the raw material building blocks
used to make the oligomers that form the basis of the OPV
compositions. For overprint varnish applications the overprint
varnish of the present invention can be formulated to have
viscosities of less than 500 cP, preferably less than 300 cP, more
preferably less than 200 cP measured at 25.degree. C. All amounts
given throughout the application are in wt % based on the total
weight of the overprint varnish composition unless otherwise
indicated.
[0038] Having thus described the invention, the following examples
are provided as illustrative in nature and should not be construed
as limiting.
[0039] Application of overprint varnishes to a variety of
substrates in the following examples was accomplished using a
suitable hand-proofer. A Pamarco spring loaded flexographic proofer
was employed for making the prints. It utilizes an anilox roll,
which has a carrying capacity of 2.8 bcm. Cure was achieved by
exposure to a single 600 W Fusion "H" bulb or a UVT "Maxim" medium
pressure mercury lamp at the specified dose.
[0040] OPV performance properties were measured by a variety of
different test methods. For purposes of defining properties by
means familiar to others skilled in the art, the following test
methods were utilized:
1 Property ASTM or Measurement Method Viscosity of OPV formulation
Brookfield CAP 2000 Viscometer Cure response Tack measured by
rubbing cotton swab over the cured surface Adhesion ASTM 2359
modified Gloss Byk Tri Gloss Meter, 60.degree.
[0041] The following are the evaluation criteria utilized for
assessment of varnishes in the following examples:
[0042] Gloss--Measured using a Byk Tri Gloss Meter at a 60.degree.
incident angle. Typically in order to be considered a high gloss
finish the gloss value as measured using the Byk Tri Gloss Meter is
about 60 or above, preferably 80 or above.
[0043] Adhesion to various substrates--ASTM 2359 test reports
values 0B to 5B with 0B being a total failure and 5B exhibiting
excellent adhesion. Adhesion testing was performed by the
non-crosshatch method due to low coating thicknesses.
EXAMPLE
[0044] The following examples illustrate the constitution,
application, cure and performance properties of OPV formulations
detailed in this disclosure. Definition of each experimental
oligomer is found in Table 1. All constituents are in parts per
hundred by weight.
2TABLE 1 Description of experimental oligomers Resin Viscosity
Designation Raw Materials [composition in wt. %] (cps @ 25.degree.
C.) 7001-152 62.9 HDDA / 14.8 MDI-DA / 13.4 EAA / 6.4 DEA / 2.5
catalyst 560 package FlexCure OPV 46.1 HDDA / 12.2 MDI-DA / 22.9
Genomer 3364 / 11.0 EAA/ 5.30 611 120 DEA / 2.5 catalyst package
FlexCure OPV 59.9 HDDA / 14.5 epoxy acrylate / 12.0 Actilane 584 /
10.7 475 130 pentanedione / 2.5 catalyst package FlexCure OPV 51.6
HDDA / 15.12 MDI-DA / 14.2 Actilane 584 / 10.5 EAA/ 1.4 645 140
pentanedione / 4.8 DEA / 2.5 catalyst package 7219-061 56.7 HDDA /
13.7 epoxy acrylate / 12.1 Actilane 584 / 1.8 acrylate 413
functional silicone copolyol / 10.2 pentanedione / 3.1 (DEA + DBA)
2.5 catalyst package 7069-143 14.6 Actilane 584 / 53.0 HDDA / 14.1
MDI-DA / 3.7 pentanedione 213 / 5.8 glycidyl acetoacetate / 4.8
2-(4-chlorobenzoyl)benzoic acid) / 3.5 DEA / 0.5 catalyst package
7069-169 15.4 epoxy acrylate / 55.6 HDDA / 13.8 Actilane 584 / 6.1
glycidyl 235 acetoacetate / 5.0 2-(4-chlorobenzoyl)benzoic acid) /
3.7 DEA / 0.4 catalyst package 7069-181 27.5 epoxy acrylate / 48.4
HDDA / 9.0 TMPTA / 6.0 glycidyl 541 acetoacetate / 5.0
2-(4-chlorobenzoyl)benzoic acid) / 3.6 DEA / 0.5 catalyst package
FlexCure OPV 57.1 HDDA / 14.2 epoxy acrylate / 4.7 TMPTA / 6.7
TMPEOTA / 296 150 6.1 pentanedione / 5.5 2959AA / 3.3 (DEA + DBA) /
2.5 catalyst package 3233R 47.8 HDDA / 12.3 epoxy acrylate / 12.3
Ebecryl 81 / 13.6 Laromer 1036 PE 55F / 5.9 EAA / 4.6 pentanedione
/ 1.0 DEA / 2.5 catalyst package
[0045] Genomer 3364 is an amine-modified polyether acrylate from
Rahn USA. Actilane 584 is an amine-modified acrylate from
AKZO-Nobel Resins. 2959AA is the mixed acetoacetate product of
2-Hydroxy-1-[4-(2-hydroxy-ethoxy)-ph- enyl]-2-methyl-propan-1-one
and t-butyl acetoacetate or diketene. DEA is diethanol amine. DBA
is dibutyl amine. Laromer PE 55F is a polyester acrylate available
from BASF AG.
[0046] Resin synthesis: A Michael addition resin is equivalently
termed a Michael polyacrylate resin, a Michael oligomer, a Michael
adduct, or a Michael addition product. A preferred Michael OPV
resin, FlexCure OPV 130 was synthesized as follows: hexanediol
diacrylate (HDDA, 59.9 g), amine acrylate (Actilane 584, 12.3 g),
epoxy acrylate (Dow XZ 92551.00, 14.6), 2,4-pentanedione (2,4-PD,
10.7 g), glycidyl methacrylate (2.0 g), and tetrabutylammonium
bromide (0.5 g) [GMA and tetrabutylammonium bromide comprise the
"catalyst package" as described in Table 1] were weighed into a 250
ml 3-neck round bottom flask equipped with a mechanical stirrer and
condenser. The solution was heated to 95 .degree. Celsius and held
at that temperature until 100% disubstitution of the Michael donor
was achieved, as defined by .sup.13C NMR. After 2.5 h, a viscous
yellow liquid having a cone and plate viscosity of 475 cP was
obtained. The yellow liquid did not gel upon standing.
[0047] Resins 7219-061, 3233-R and OPV 150 were all synthesized by
the same procedure.
[0048] In the case of 7001-152, FlexCure OPV 120 and OPV 140,
aromatic urethane acrylate, MDI-diacrylate (MDI-DA), was first
synthesized in the reactor by the stoichiometric reaction of
methylene diphenyl diisocyanate with hydroxyethyl acrylate in the
presence of a tin catalyst. The Michael resin containing the MDI-DA
was then synthesized by the same procedure as OPV 130, mixing in
the rest of the reactants and heating to 95 .degree. Celsius and
holding at that temperature until 100% disubstitution of the
Michael donor was achieved, as defined by .sup.13C NMR. After 4 h,
the reaction was cooled down and a secondary amine, diethanol amine
was added to cap a portion of the acrylate groups.
[0049] Synthesis of 7069-169 from Table 1:
[0050] Hexanediol diacrylate, 114.8 g, Actilane 584 (Akzo Nobel
Resins), 31.7 g, XZ 92551.00 epoxy acrylate, 28.5 g, glycidyl
acetoacetate (GAA), 12.5 g and tetrabutylammonium bromide, 0.96 g,
were combined according to the method described in U.S. Pat. No.
6,706,414. The reactor temperature was set to 95.degree. C. and
held at that temperature until 100% disubstitution of the Michael
donor was achieved, as defined by a refractive index measurement.
2-benzoylbenzoic acid, 10.3 g, was added and the reactor held at
temperature until no epoxy groups were detected by FTIR. After 7
hours total cook time, diethanol amine, 7.6 g, was added to the
mixture and the reaction product was cooled to room temperature
with stirring. The final product was a low viscosity clear liquid
having a cone and plate viscosity of 230 cP.
[0051] Syntheses of resins 7069-143 and 7069-181 was achieved by
the same method as 7069-169.
[0052] OPV formulations: The OPV formulations were made by mixing
all the components described in the examples, in a Hauschild
centrifugal mixer for 2 to 3 minutes at 2500 sec.sup.-1.
Example 1
OPV Formulation Based on FlexCure Resins
[0053] The final formulation (OPV-062503-01) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 1A:
3TABLE 1A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) 7001-152 Ashland self-initiating resin 68.0
TMPTA reactive diluent 28.0 Benzophenone photoinitiator 1.0 MDEA
amine synergist 0.4 HCPK photoinitiator 0.6 TegoRad 2300
siloxane-based flow agent 2.0 100.0
Example 2
OPV Formulation Based on FlexCure Resins
[0054] The final formulation (OPV-102003-02) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 2A:
4TABLE 2A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) FlexCure Resin OPV120 Ashland
self-initiating resin 60.0 TMPTA reactive diluent 36.0 Benzophenone
photoinitiator 1.0 MDEA amine synergist 0.4 HCPK photoinitiator 0.6
TegoRad 2300 siloxane based flow agent 2.0 100.0
Example 3
OPV Formulation Based on FlexCure Resins
[0055] The final formulation (OPV-070903-02) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 3A:
5TABLE 3A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) FlexCure OPV130 Ashland self-initiating
resin 67.0 TMPTA reactive diluent 28.0 Benzophenone photoinitiator
1.5 MDEA amine synergist 0.6 HCPK photoinitiator 0.9 TegoRad 2300
siloxane based flow agent 2.0 100.0
Example 4
OPV Formulation Based on FlexCure Resins
[0056] The final formulation (OPV-121003-O1) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 4A:
6TABLE 4A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) FlexCure OPV140 Ashland self-initiating
resin 60.0 TMPTA reactive diluent 35.0 Benzophenone photoinitiator
1.0 MDEA amine synergist 0.4 HCPK photoinitiator 0.6 LG 99
slip-additive 1.0 TegoRad 2300 siloxane based flow agent 2.0
100.0
Example 5
OPV Formulation Based on FlexCure Resins
[0057] The final formulation (OPV-111504-04) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 5A:
7TABLE 5A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) 7219-061 Ashland self-initiating resin 80.0
TMPTA reactive diluent 18.0 Benzophenone photoinitiator 1.0 MDEA
amine synergist 0.4 HCPK photoinitiator 0.6 100.0
Example 6
OPV Formulation Based on FlexCure Resins
[0058] The final formulation (OPV-120903-07) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 6A:
8TABLE 6A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) 7069-143 Ashland self-initiating resin 96.0
LG 99 reactive foam control agent 1.0 MDEA amine synergist 0.4 HCPK
photoinitiator 0.6 TegoRad 2300 siloxane based flow agent 2.0
100.0
Example 7
OPV Formulation Based on FlexCure Resins
[0059] The final formulation (OPV-010204-03) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 7A:
9TABLE 7A Formulation (components in parts by weight). Raw Material
Description Parts (w/w) 7069-169 Ashland self-initiating resin 97.0
LG 99 reactive foam control agent 1.0 TegoRad 2300 siloxane based
flow agent 2.0 100.0
Example 8
OPV Formulation Based on FlexCure Resins
[0060] The final formulation (OPV-010804-02) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 8A:
10TABLE 8A Formulation (components in parts by weight). Raw
Material Description Parts (w/w) 7069-169 Ashland self-initiating
resin 87.0 TMPTA reactive diluent 10.0 LG 99 reactive foam control
agent 1.0 TegoRad 2300 siloxane based flow agent 2.0 100.0
Example 9
OPV Formulation Based on FlexCure Resins
[0061] The final formulation (OPV-041504-02) is comprised of
FlexCure resins and commercial raw materials, in parts by weight,
as specified in Table 9A:
11 Formulation Table 9A (components in parts by weight). Raw
Material Description Parts (w/w) FlexCure OPV150 Ashland
self-initiating resin 97.0 LG 99 reactive foam control agent 1.0
TegoRad 2300 siloxane based flow agent 2.0 100.0
[0062]
12TABLE 2 Performance evaluation of experimental OPV formulations
on coated paper: Adhesion Dosage for (coated Viscosity tack- paper,
board @ 30.degree. C. free cure Gloss stock, PET, Formulation % PI
(cP) (mJ/cm.sup.2) (60.degree.) BOPP) OPV-062503-01 2.0 240 <200
80.4 5B OPV-102003-02 2.0 237 <200 90.1 5B OPV-070903-02 3.0 237
<200 89.9 5B OPV-121003-01 2.0 240 <200 91.2 5B
OPV-1111504-04 2.0 249 <200 92.1 5B OPV-120903-07 1.0 174
<200 92.4 5B OPV-010204-03 0.0 216 <200 90.5 5B OPV-010804-02
0.0 375 <200 94.9 5B OPV-041504-02 0.0 258 <200 93.7 5B
Example 10
OPV Formulation for Plastic Substrates Based on FlexCure Resins
[0063] The final formulation 3233R-10A is comprised of FlexCure
resins and commercial raw materials, in parts by weight, as
specified in Table 10A:
13 Formulation Table 10A (components in parts by weight). Raw
Material Description Parts (w/w) 3233R Ashland self-initiating
resin 99.0 TegoRad 2250 siloxane based flow agent 1.0 100.0
Example 11
OPV Formulation for Plastic Substrates Based on FlexCure Resins
[0064] The final formulation 3233R-11A is comprised of FlexCure
resins and commercial raw materials, in parts by weight, as
specified in Table 11A:
14 Formulation Table 11A (components in parts by weight). Raw
Material Description Parts (w/w) 3233R Ashland self-initiating
resin 68.6 TMPEOTA reactive diluent 28.4 Ebecryl P-36 polymerizable
photoinitiator 2.0 TegoRad 2250 siloxane based flow agent 1.0
100.0
[0065]
15TABLE 3 Performance evaluation of experimental OPV formulations
on plastic films: Dosage for Viscosity tack-free Adhesion Adhesion
@ 30.degree. C. cure (treated (untreated Formulation % PI (cP)
(mJ/cm.sup.2) OPP) PET) 3233R-10A 0.0 835 (see below) Lamp Type
Fusion 600 0.0 395 5B 5B W H Fusion 300 0.0 415 5B 5B W H UVT Maxim
0.0 345 5B 5B 400 W UVT Maxim 0.0 481 5B 5B 200 W UVT Maxim 0.0 608
5B 5B 100 W 3233R-11A 2.0 345 (see below) Lamp Type Fusion 600 2.0
415 5B 5B W H Fusion 300 2.0 453 5B 5B W H UVT Maxim 2.0 284 5B 5B
400 W UVT Maxim 2.0 422 5B 5B 200 W UVT Maxim 2.0 502 5B 5B 100
W
[0066] The examples listed in the above Tables 2 and 3 quantify the
performance of various varnishes formulated with self-initiating
resins. An obvious advantage of OPV formulations based on resins
built with self-initiating Michael addition resin technology is the
low photoinitiator requirement to achieve the desired cure, gloss
and adhesion levels. In examples 7A, 8A and 9A, no photoinitiator
at all was utilized. This advantage translates into both
significant cost savings and handling benefits from using less of
the traditional photoinitiators which can be toxic and/or
malodorous, and are often difficult to dissolve in monomers. In
addition, they can contribute to film color, which can limit
applicability over white and light-colored inks.
* * * * *