Note: Descriptions are shown in the official language in which they were submitted.
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WATER-BORNE AQUEOUS EPOXY-ESTERIACRYLATE AND POLY(URETHANE-
UREA) BASED CROSSLINKED RESINS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to water-borne crosslinkable resin compositions. More
particularly, this invention relates to water-borne crosslinkable printing ink
compositions for
printing on low density polyethylene films.
Description of Related Art
Over the years, the printing industry has turned to flexography to print
images onto
deformable surfaces such as polymeric films, fabrics, as well as to print
conventional
products in the publishing industry. Flexography is a branch of rotary
typographic printing
in which the printing is applied to a substrate surface by use of a flexible
relief plate and
highly fluid, volatile solvent based inks which dry rapidly by evaporation. In
recent years,
increased emphasis has been placed on using water as the solvent, rather than
volatile
organic solvents; and a wide variety of colorants have been developed for use
in these
water-based ink formulations. Recent advances in water-based ink formulations
are
illustrated, by Levy et al., in U.S. Patent 5,853,859 and by Hutter in U.S.
Patent 5,498,661.
Levy et al. disclose printing compositions for printing fabric comprising
thermoplastic polyolefin fibers. Levy's printing compositions comprise a room
temperature
curable latex polymer, pigment and a cure promoter. The composition is applied
to fabric
as an aqueous mixture with a pre-cure pH adjusted to above 8 using a fugitive
alkali. The
composition is then cured at room temperature. The dried residue of the
aqueous mixture
retains color-fastness when exposed to liquids with a pH between about 2 and
about 13 so
that the dried residue will remain on the fabric when exposed to most common
cleaning
chemicals and under most conditions of use.
Hutter discloses acrylic latex binders for use in preparing zinc-containing
water-
base inks for printing on plastic films such as polypropylene, polyester, and
the like. The
binder results from an addition emulsion polymerization reaction of four
individual
components. Inks containing these binders exhibit increased chemical
resistance to
commonly-used cleaning formulations and offer excellent heat and water-crinkle
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resistance.
While advances have been made in water-based ink formulations for generally
printing plastic films and fabrics, there continues to be a need for an
aqueous based inks
suitable for printing on low-density polyethylene films to form chemical-
resistant, adherent,
dried ink images which do not block with other surfaces or itself, e.g., as
when stored in
roll form or with other substrate surfaces.
SUMMARY OF THE INVENTION
The above mentioned needs are met by aqueous printing inks which are derived
from an aqueous crosslinkable resin system having a pH greater than 7
comprising:
(A) a water-dispersible poly(urethane/urea) being the reaction product of a
polyurethane
prepolymer prepared from a diisocyanate component and a diol component;
wherein the
NCO/-OH ratio is between 1 and 2; and containing 1 to 8 % by weight of
unreacted -NCO
and carboxylic acid groups and between 110 % and 200 % of a diamine, based on
the
equivalents of the unreacted -NCO groups; wherein the resulting
poly(urethane/urea)
contains terminal amino groups and -C02 A+ groups; wherein A+ is an onium ion
of
ammonia or a volatile amine; and
(B) a water-dispersible poly(epoxy/ester/acrylate) being an epoxy/ester
prepolymer grafted
with an acrylic component; wherein, (a) the epoxy/ester prepolymer is prepared
from a
condensation polymer of an aryl, alkyl or alkaryl dihydroxy compound with a
aryl, alkyl or
alkaryl bis-oxirane compound, and an unsaturated fatty acid and, (b) the
acrylic
component contains reactive keto groups and -C02 B+ groups, .wherein B+ is a
second
onium ion of ammonia or the volatile amine; whereby the resulting
poly(epoxy/ester/acrylate) contains residual ethylenic unsaturation; and
(C) water.
A further embodiment of this invention is a method for producing a cured film
on a
substrate comprising the steps of: applying the above described aqueous
crosslinkable
resin system onto a surface of the substrate to form a coating and drying the
coating to
initiate curing; wherein the film formed is tack-free, firmly adherent to the
surface of the
substrate, and un-blocked when contacted under pressure to a second surface of
the
substrate or a second substrate.
In a preferred embodiment of this invention, the film is further crosslinked
by
oxidative crosslinking of the residual ethylenic unsaturation.
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A still further embodiment of this invention is an aqueous, crosslinkable
printing ink
having a pH greater than 7 comprising:
(A) a water-dispersible poly(urethane/urea) being the reaction product of a
polyurethane
prepolymer prepared from a diisocyanate component and a diol component;
wherein the
NCO/-OH ratio is between 1 and 2; and containing 1 to 8 % by weight of
unreacted -NCO
and carboxylic acid group; and
between 110 % and 200 % of a diamine, based on the equivalents of the
unreacted -NCO
groups; wherein the resulting poly(urethane/urea) contains terminal amino
groups and -
C02 A+ groups; wherein A+ is an onium ion of ammonia or a volatile amine;
(B) a water-dispersible poly(epoxy/ester/acrylate) being an epoxy/ester
prepolymer grafted
with an acrylic component; wherein (a) the epoxy/ester prepolymer is prepared
from a
condensation polymer of an aryl, alkyl or alkaryl dihydroxy compound with
aryl, alkyl or
alkaryl a bis-oxirane compound, and an unsaturated fatty acid and (b) the
acrylic
component contains reactive keto groups and -COZ B+ groups, wherein B+ is a
second
onium ion of ammonia or the volatile amine; whereby the resulting
poly(epoxy/ester/acrylate) contains residual ethylenic unsaturation;
(C) water;
(D) a colorant, fluorescing agent, or mixture thereof; and optionally,
(E) an oxidative crosslinking agent; and
(F) a dispersing agent.
A still further embodiment of this invention is a method for printing an image
on a
substrate comprising the steps: applying the aqueous, crosslinkable printing
ink of this
invention onto the surface of the substrate to form an image; and drying the
image to
initiate curing; wherein the print image formed is tack-free, firmly adherent
to the surface of
the substrate, and un-blocked when contacted under pressure to a second
surface of the
substrate or to a second substrate.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a novel water based dual crosslinking resin
system
between a water borne epoxy/ester/acrylate copolymer component containing
reactive
keto groups and ethylenic unsaturation, and a water-borne poly(urethane/urea)
component
containing terminal amino groups. Both components contain ammonium carboxylate
salt
groups derived from carboxylic acid groups and ammonia or a fugitive amine so
that the
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water based crosslinking system can be neutral or basic. More particularly,
the present
invention relates to a novel water based flexographic packaging ink which
exploits this
dual crosslinking resin system. While not wishing to be bound by theory, it is
believed that
when the printing ink is applied to a substrate and dried, the ammonia or
fugitive amine is
lost and the pH becomes acidic which in turn initiates crosslinking. Thus, the
poly(urethane/urea) component provides the required amine functionality for
the
predominant crosslinking to take place in the dried ink with reactive keto
groups on the
epoxy-ester/acrylate copolymer component. Additionally the amine functionality
of the
poly(urethane/urea) provides adhesion to an underlying substrate. The
ethylenic
unsaturation of the epoxy-ester/acrylate copolymer additionally allows the
copolymer to
undergo secondary oxidative crosslinking when used with metal drying
compounds. This
ink system exhibits excellent block resistance, printability, resolubility,
and adhesion on low
density polyethylene film products such as those used to manufacture diapers
and other
such personal care products.
Aqueous Crosslinkable Resin
The aqueous crosslinkable resin system of this invention comprises a water-
borne
poly(urethane/urea) hereinafter described; a water-borne
poly(epoxy/ester/acrylate)
hereinafter described; and water in which the resin system has a pH of 7 or
greater. As
used herein the terms "water borne" and "water-dilutable" are intended to mean
a material
that is either a water dispersion or a water solution of the material or that
the material is
capable of being dissolved or dispersed in water as a stable suspension or
solution.
Typically, these aqueous crosslinkable resin systems comprise about 25 to
about 30 wt.%
of the water-borne poly(urethane/urea); about 15 to about 20 wt.% of the water-
borne
poly(epoxy/ester/acrylate); and about 10 to about 15 wt.% of water, based on
the total
weight of the resin system. The aqueous crosslinkable resin system may further
comprise
an oxidative crosslinking agent; a colorant; a fluorescent agent ; or any
mixture thereof.
The system may additionally contain conventional adjuvants such as dispersing
agents,
matting agents, waxes, silicones, and the like.
Poly(Urethane/Urea) Component
The water-dispersible poly(urethane/urea) component of this invention contains
terminal amino groups, and ammonium carboxylate salt groups derived from
carboxylic
acid groups and ammonia or a fugitive amine, i.e., -C02 A+ groups, wherein A+
is an
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onium ion of ammonia or the fugitive (i.e., volatile) amine. This
poly(urethane/urea)
component comprises a reaction product of a polyurethane prepolymer and a
diamine,
such as hydrazine.
The polyurethane prepolymer is a polyurethane polymer having two terminal
isocyanate groups and has the Structure I:
OCN-(-Q-N H-CO-O-R2-O-CO-N H-)~-Q-N H-CO-O-R2-O-CO-N H-Q-N CO
wherein -Q- is an aryl or alkyl group; and R2 comprises R3 and R4 , wherein R3
is a
polymeric group, and wherein R4 is an alkyl group containing the carboxylic
acid group or
the -C02 A+ group and wherein the polyurethane prepolymer contains 1 to 8.0
wt.% of
unreacted -NCO groups. Typically, R2 comprises from about 30 to about 80
equivalent
of R3 and preferably further comprises R5 which is an alkyl group; with the
molar ratio of
R3 to R4 being in the range from 70:30 to 95:5. Preferably the ratio of R3 to
R4 is about
85:15. The polyurethane prepolymer used in this invention may additionally
contain up to
about 10 wt. % of a second polyurethane polymer having a single terminal
isocyanate
group having the Structure II:
OCN-(-C~-N H-CO-O-R2-O-CO-N H-)"-Q-N H-CO-O-R2-O-CO-N H-Q-N H-CO-N H-J
wherein -Q- is an aryl or alkyl group; and R2 comprises R3 and R4 , wherein R3
is a
polymeric group, and wherein R4 is an alkyl group containing the carboxylic
acid group or
the -C02 A+ group, and J is a methoxypoly(oxyethylene/oxypropylene)-2-2propyl
group.
Preferably, the polyurethane prepolymer used in this invention contains from
about 90
wt.% to about 98 wt.% of the polyurethane polymer of Structure I; and from
about 10 wt.%
to about 2 wt.% of the second polyurethane polymer of Structure II.
The polyurethane prepolymer is prepared from a diisocyanate component and a
diol
component so that the -NCO/-OH ratio is between 1 and 2 and, preferably, is
about 1.5.
The "-NCO/-OH ratio" as used herein, has its conventional meaning which is the
ratio of
the number of equivalents of -NCO groups in the diisocyanate component, to the
number
of equivalents of -OH groups in the diol component. The resulting polyurethane
prepolymer contains 1 to 8 wt. % by weight of unreacted -NCO groups, and 1 to
25 wt.
carboxylic acid groups. Preferably the polyurethane prepolymer contains about
5 wt. % of
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unreacted -NCO groups, and about 10 wt.% carboxylic acid groups. Preferably
the
polyurethane prepolymer is prepared from a diisocyanate component comprising
an
aryldiisocyanate or an alkyldiisocyanate; a diol component comprising a
polymeric diol, a
diol-alkanoic acid; and optionally, an alkane diol, an alkoxylated amine, or a
mixture
thereof.
In the preparation of the prepolymer, a number of aryldiisocyanates or
alkyldiisocyanates may be used such as 4,4'-diphenylmethane diisocyanate; 4,4'-
dicyclohexyl diisocyanate; hexamethylene diisocyanate; isophorone
diisocyanate; toluene
diisocyanate, or meta-tetramethylene- xylenediisocyanate; of which meta-
tetramethylene-
xylenediisocyanate is preferred.
The polymeric diol used in this preparation has a molecular weight (MW) from
about
650 to about 4000 and is selected from the group consisting of a polyether
diol, a
polyethylene diol, a polycaprolactone diol and a polypropylene diol. A number
of polyether
diols may be used such as PEG 650, PEG 1000, PEG 2000, PEG 3000, PEG 4000, or
alpha-hydro-omega-hydroxy-poly(oxy-1,4-butyldiyl). A particularly preferred
polyether diol
is alpha-hydro-omega-hydroxy-poly(oxy-1,4-butyldiyl) having a MW of about
1000.
In the preparation, of the polyurethane prepolymer, a number of alkanoic acids
may
be used such as dimethylolpropionic acid, dimethylolbutanoic acid, and the
like. A
particularly preferred alkanoic acid is dimethylolpropionic acid or
dimethylolbutanoic acid.
In the preparation a number of alkane diols may be used such as 1,4-
butanediol,
1,5-pentanediol, or 2-methyl-1,3-propanediol. A particularly preferred
alkanediol is 2-
methyl-1,3-propanediol.
In the preparation of the prepolymer, a number of alkoxylated amines may be
used.
Preferably the alkoxylated amine is an ethoxylated amine, a propoxylated amine
or a
combination thereof, such as methoxy-poly(oxyethylene/oxypropylene)-2-
propylamine. A
particularly preferred alkoxylated amine is methoxy-
poly(oxyethylene/oxypropylene)-2-
propylamine.
Preferably, the polyurethane prepolymer is prepared from about 10 to about 70
parts by weight of the polymeric diol; about 10 to about 70 parts by weight of
the
aryldiisocyanate or the alkyldiisocyanate; about 1 to about 30 parts by weight
of the diol-
alkanoic acid; 0 to about 30 parts by weight of the alkane diol; and 0 to
about 25 parts by
weight of the alkoxylated amine. The reaction mixture for preparing the
prepolymer may
also contain 0 to about 2 parts by weight of a polymerization catalyst (e.g.,
a tin or zinc
based catalyst), and 0 to about 25 parts by weight of an organic co-solvent
such as ethyl
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acetate. As used in the preparation herein, the co-solvent may also function
as the
processing solvent used in the preparation of the aqueous crosslinkable
polymeric resin.
The polyurethane prepolymer is reacted with between 110 % and 200 % of the
diamine, based on the equivalents of the unreacted -NCO groups in the
prepolymer; then
neutralized with ammonia or a fugitive or volatile amine. As used herein a
"fugitive amine"
includes volatile amines which readily evaporate at room temperatures.
Typically, the
volatile amines will contain 1 to 5 carbon atoms and include alkyl amines or
an
alkanolamines such as t-butyl amine, triethyl amine, ethanolamine, methyl
ethanolamine,
N,N-dimethylethanol-amine. A preferred alkanolamine is N,N-dimethylethanol-
amine. A
number of diamines may be used for preparing the poly(urethane/urea) of this
invention,
such as hydrazine, alkyl substituted hydrazines, methylenediamine,
ethylenediamine,
diamino cyclohexane, hexamethylene diamine, piperazine, or isophorone diamine.
A
particularly preferred diamine is hydrazine.
As illustrated in the following examples, the poly(urethane/urea) component is
prepared by first preparing the polyurethane prepolymer in a processing (co-
solvent) as
described above. The resulting prepolymer is slowly added to an aqueous
solution of the
diamine and the ammonia or fugitive amine at raised temperatures to produce a
water-
dispersible poly(urethane/urea). The water-dispersible poly(urethane/urea)
prepared by
this method is an aqueous dispersion comprising about 15 to about 70 wt. % of
the
poly(urethane/urea); about 30 to about 85 wt. % water; and 0 to about 25 wt. %
of a
processing solvent such as 1-propoxy-2-propanol. The poly(urethane/urea)
prepared by
this method has the Structure III:
N H2-R~-N H-CO-N H-(-U-N H-CO-N H-R~-N H-CO-N H-)m-U-N H-CO-N H-R~-N H2
wherein R~ is a covalent bond or a C~_3 alkyl group and -U- has the Structure
IV:
-(-Q-N H-CO-O-R2-O-CO-N H-)~-Q-N H-CO-O-R2-O-CO-N H-Q-
wherein -Q- is an aryl or alkyl group; and Rz comprises R3 and R4 , wherein R3
is an alkyl
or a polymeric group, and wherein R4 is an alkyl group containing the -C02 A+
group.
When the poly(urethane/urea) is prepared from the polyurethane prepolymer
containing
both the polyurethane polymer of Structure I and the second polyurethane of
Structure II,
the poly(urethane/urea) additionally contains a second poly(urethane/urea)
polymer of
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Structure V:
N H2-R~-N H-CO-N H-(-U-N H-CO-N H-R~-N H-CO-N H-),,-,-U'
wherein R~ is a covalent bond or an alkyl group having 1-3 carbon atoms; -U-
has the
Structure IV:
-(-Q-N H-CO-O-R2-O-CO-N H-)n-Q-N H-CO-O-R2-O-CO-N H-Q-
and -U' has the Structure V1:
-(-Q-N H-CO-O-R2-O-CO-N H-)n-Q-N H-CO-O-R2-O-CO-N H-Q-N H-CO-N H-J
wherein -Q- is an aryl or alkyl group; and R2 comprises R3 and R4 , wherein R3
is an alkyl
or a polymeric group, wherein R4 is an alkyl group containing the -C02 A+
group; and
wherein J is a methoxypoly(oxyethylene/oxypropylene)-2-2propyl group. A
preferred
water-dispersible poly(urethane/urea) of this invention is propanoic acid,3-
hydroxy-2-
(hydroxymethyl)-2-methyl, polymer with 1,3-bis(1-isocyanato-1-
methylethyl)benzene,
hydrazine, alpha-hydro-omegahydroxypoly-9oxy-1,4-butanediyl) and 2-methyl-1,3-
propanediol, ammonium salt, polyethylene-polypropyleneglycol 2-aminopropyl
methyl ethyl
(ME) ether blocked.
Poly(Epoxy/Ester/Acrylate) Component
The water-borne poly(epoxy/ester/acrylate) component of this invention
contains,
reactive keto groups, residual ethylenic unsaturation, and ammonium
carboxylate salt
groups derived from carboxylic acid groups and ammonia or a volatile amine. In
particular,
the water-borne poly(epoxy/ester/acrylate) component comprises a
polymerization product
of an epoxy/ester prepolymer grafted with an acrylic component in a processing
solvent.
In particular, the water-dispersible poly(epoxy/ester/acrylate) has the
structure:
EE ACo
wherein EE is an epoxy/ester prepolymer of the structure:
FA-CHZ-CH(OH)-(-Rio-CH(OH)-CHz-O-R"-O-CHZ-CH(OH)-)p R,o-CH(OH)-CHZ-FA ;
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wherein R1o and R11 are individually selected from alkyl, aryl or alkaryl
groups, and FA is a
fatty acid ester group having the structure:
CH3-(CH2)q-CH=CH-(CH2),-CO-O- ; and
wherein ACo is the acrylic component comprising one or more acrylic polymer
moieties
randomly bonded to the epoxy/ester prepolymer, wherein each acrylic polymer
moiety has
the structure:
R12 R12 R12
-(-CH2-C-)S-(-C H2-C-)t-(-CH2-C-)"-R1 s
C02 B+ CO-R15 C02-R14
wherein each R12 individually is selected from hydrogen or an alkyl group; R13
is a chain
termination group; R14 is an alkyl group; and R15 is an ester group which
contains a keto
group, or an amide group which contains a keto group; and wherein o, p, q, r,
s, and t each
individually are positive integers, while a is zero or a positive integer.
Each acrylic polymer
moiety has a random copolymer structure and the integers s, t, and a simply
designate the
number of moieties in the acrylic component. Preferably, R15 is a
diacetoneamide group; a
is a positive integer; and R14 is a butyl group
The epoxy/ester prepolymer is a condensation polymer of a bis-phenol-A with an
aromatic bis-oxirane, and an unsaturated fatty acid. In particular, the
epoxy/ester
prepolymer is prepared from a reaction mixture comprising: about 5 to about 80
parts by
weight of a condensation polymer of bis-phenol-A with an aromatic bis-oxirane;
about 5 to
about 70 parts by weight of the unsaturated fatty acid; 0 to about 1 part by
weight of a
polymerization catalyst; and about 10 to about 80 parts by weight of the
processing
solvent. Bis-phenol A compounds useful in preparing the condensation polymer
include,
bis-phenol A (i.e., 2,2-(4-hydroxyphenyl)propane). Aromatic bis-oxirane
compounds useful
in preparing the condensation polymer include 2,2'-{(1-
methylethylidine)bis(4,1-phenylene-
oxymethylene)}bis(oxirane). Preferably the condensation polymer is derived
from bis-
phenol A polymerized with 2,2'-{(1-methylethylidine)bis(4,1-phenylene-
oxymethylene)}bis(oxirane). Unsaturated fatty acids which are useful in
preparing the
epoxy/ester prepolymer may be selected from the group consisting of linoleic;
linolenic;
and oleic acid; and mixtures thereof. A preferred unsaturated fatty acid is a
fatty acid
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mixture containing 39 wt. % linoleic acid; 40 wt. % of linolenic acid; and 21
wt. % of oleic
acid; and a particularly preferred unsaturated fatty acid is this fatty acid
mixture which
contains additional linoleic acid.
The acrylic component which is grafted to the epoxy/ester prepolymer, contains
reactive keto groups and -C02 B+ groups, in which B+ is an onium ion of
ammonia or the
volatile amine. B+ is an onium ion of ammonia or the volatile amine and may be
the same
as A+ described previously in connection with the poly(urethane/urea)
component.
Preferably the acrylic component comprises: about 1 to about 30 parts by
weight of
diacetone acrylamide; about 1 to about 20 parts by weight of acrylic acid,
methacrylic acid
or a mixture thereof; about 0 to about 30 parts by weight of an alkyl
acrylate; about 0.1 to
about 5 parts by weight of a polymerization initiator; and about 1 to about 50
parts by
weight of the processing solvent such as 1-propoxy-2-propanol. The alkyl
acrylate may
be a C~_5 alkyl acrylate with butyl acrylate being preferred. The grafted
polymerization
product is neutralized with ammonia or the volatile amine. When a volatile
amine is used,
it typically contains 1 to 5 carbon atoms, and is an alkyl amine or an
alkanolamine such as
t-butyl amine, triethyl amine, ethanolamine, methylethanolamine, N,N-
dimethylethanol-
amine, and the like. A preferred alkanolamine is N,N-dimethylethanol-amine.
As illustrated in the following examples, the epoxy resin is first esterified
with an
unsaturated fatty acid in the presence of a metal catalyst, such as zirconium
2-
ethylhexoate. The resulting epoxy/ester is grafted with the acrylic component
in the
presence of an initiator compound such as azoisobutyronitrile. The water-
dispersible
poly(epoxy/ester/acrylate) prepared in this invention is an aqueous solution
comprising
about 10 to about 85 wt.% of the poly(epoxy/ester/acrylate); about 15 to about
90 wt.
water; and 0 to about 40 wt. % of a processing solvent. A preferred water-
dispersible
poly(epoxy/ester/acrylate) of this invention is phenol 4,4'-(1-
methylethylidene)bis, polymer
with (chloromethyl) oxirane, reaction products with C~$ unsaturated fatty
acids, copolymers
with butyl 2-propenoate, 2-methyl-2-propenoic acid and N-(1,1-dimethyl-3-
oxobutyl)acrylamide, compound with N,N-dimethylethanolamine.
Oxidative Crosslinking Agent
The aqueous crosslinkable resin system of this invention may contain an
oxidative
crosslinking agent to facilitate the oxidative crosslinking of the residual
ethylenic
unsaturation of the dried resin system. Such oxidative crosslinking agents are
particularly
useful for the dual curing inks using the crosslinkable resin system of this
invention. While
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most of such agents are useful, preferred oxidative crosslinking agents
include metal salts
of a fatty acids wherein the metal is manganese, cobalt, or zinc. A few
examples of such
metal salts are more fully described in connection with the preparation of
printing inks
under this invention.
Colorant/ Fluorescing Agent
The aqueous crosslinkable resin system of this invention may contain a
colorant
such as a dye or pigment, a fluorescing agent, or a mixture thereof.
Alternatively, the
colorant may possess the dual function of a fluorescing coloring agent.
Colorants have
their conventional function of imparting a visible color with a desired hue
and density.
Fluorescing agents have the function of imparting a marking typically not
visible without
the aid of stimulating radiation outside the visible spectral region.
Although, colorants and
fluorescing agents may or may not be incorporated into any crosslinkable resin
system of
this invention, when used they form a component of the dual crosslinkable
printing ink of
this invention.
The resin systems of this invention when used in aqueous crosslinkable
printing
inks, typically contain one or more colorants such as a soluble dye or solid
pigment. Such
inks may typically contain one or more conventional solid pigments dispersed
therein.
The pigment used may be any conventional organic or inorganic pigment such as
Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13,
Pigment
Yellow 14, Pigment Yellow 17, Pigment Yellow 63, Pigment Yellow 65, Pigment
Yellow 73,
Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 97,
Pigment
Yellow 98, Pigment Yellow 106, Pigment Yellow 114, Pigment Yellow 121, Pigment
Yellow
126, Pigment Yellow 127, Pigment Yellow 136, Pigment Yellow 174, Pigment
Yellow 176,
Pigment Yellow 188, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16,
Pigment Orange 34, Pigment Red 2, Pigment Red 9, Pigment Red 14, Pigment Red
17,
Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red
41,
Pigment Red 42, Pigment Red 112, Pigment Red 170, Pigment Red 210, Pigment Red
238, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:2, Pigment Blue 15:3,
Pigment
Blue 15:4, Pigment Green 7, Pigment Green 36, Pigment Violet 23, Pigment Black
7,
titanium dioxide, carbon black, and the like. Pigment compositions which are
also useful in
the printing inks of this invention are described in U.S. Patents 4,946,508;
4,946,509;
5,024,894; and 5,062,894 each of which is incorporated herein by reference.
Such
pigment compositions are a blend of the pigment along with a poly(alkylene
oxide) grafted
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pigment.
The classes of dyes suitable for use in present invention are selected from
acid
dyes, natural dyes, direct dyes either cationic or anionic direct dyes, basic
dyes, and
reactive dyes.
The acid dyes, also regarded as anionic dyes, are soluble in water and mainly
insoluble in organic solvents and are selected, from yellow acid dyes, orange
acid dyes,
red acid dyes, violet acid dyes, blue acid dyes, green acid dyes, and black
acid dyes.
European Patent 0 745 651, incorporated herein by reference, describes a
number of acid
dyes which are suitable for use in the present invention. The yellow acid dyes
selected
include Acid Yellow 1 (C.I. 10316); Acid Yellow 7 (C.I. 56205); Acid Yellow 17
(C.I.
18965); Acid Yellow 23 (C.I. 19140); Acid Yellow 29 (C.I. 18900); Acid Yellow
36 (C.I.
13065); Acid Yellow 42 (C.I. 22910); Acid Yellow 73 (C.I. 45350); Acid Yellow
99 (C.I.
13908); Acid Yellow 194; and Food Yellow 3 (C.I. 15985). The orange acid dyes
selected
include Acid Orange 1 (C.I. 13090/1 ); Acid Orange 10 (C.I. 16230); Acid
Orange 20 (C.I.
14603); Acid Orange 76 (C.I. 18870); Acid Orange 142; Food Orange 2 (C.I.
15980); and
Orange B. The red acid dyes selected include Acid Red 1 (C.I. 18050); Acid Red
4 (C.I.
14710); Acid Red 18 (C.I. 16255); Acid Red 26 (C.I. 16150); Acid Red 27 (C.I.
16185);
BASOVIT T"~ 425E (available from BASF Corporation) a xanthone based acid dye
also
known as Acid Red 51 (C.I. 45430); Acid Red 52 (C.I. 45100); Acid Red 73 (C.I.
27290);
Acid Red 87 (C.I. 45380); Acid Red 94 (C.I. 45440); Acid Red 194; and Food Red
1 (C.I.
14700). The violet acid dyes selected include Acid Violet 7 (C.I. 18055); and
Acid Violet
49 (C.I. 42640). The blue acid dyes selected include Acid Blue 1 (C.I. 42045);
Acid Blue 9
(C.I. 42090); Acid Blue 22 (C.I. 42755); Acid Blue 74 (C.I. 73015); Acid Blue
93 (C.I.
42780); and Acid Blue 158A (C.I. 15050). The green acid dyes selected include
Acid
Green 1 (C.I. 10028); Acid Green 3 (C.I. 42085); Acid Green 5 (C.I. 42095);
Acid Green 26
(C.I. 44025); and Food Green 3 (C.I. 42053). The black acid dyes selected
include Acid
Black 1 (C.I. 20470); Acid Black 194 (BASANTOLT"" X80, available from BASF
Corporation, an azo/1:2 CR-complex also known as.
The direct dyes selected for use in the present invention include Direct Blue
86 (C.I.
74180), Direct Red 199, Direct Red 168, Direct Red 253 (C.I. Not Assigned) and
Direct
Yellow 107/132 (C.I. Not Assigned). The direct dyes are commonly used in
coloration of
pulp paper.
The natural dyes selected for use in the present invention include Alkanet
(C.I.
75520,75530); Annatto (C.I. 75120); Carotene (C.I. 75130); Chestnut; Cochineal
(C.I.
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75470); Cutch (C.I. 75250, 75260); Divi-Divi; Fustic (C.I. 75240); Hypernic
(C.I. 75280);
Logwood (C.I. 75200); Osage Orange (C.I. 75660); Paprika; Quercitron (C.I.
75720);
Sanrou (C.I. 75100); Sandal Wood (C.I. 75510, 75540, 75550, 75560); Sumac; and
Tumeric (C.I. 75300).
The reactive dyes selected for use in the present invention include Rewactive
Yellow 37 (monoazo dye); Reactive Black 31 (disazo dye); Reactive Blue 77
(phthalo
cyanine dye) and Reactive Red 180 and Reactive Red 108 dyes.
Preference is given to the use of acid dyes such as, for example, Acid Black
194;
Acid Red 51, Acid Blue 9; Acid Green 26; Acid Yellow 36, Acid Orange 142,
Direct Blue
86, Direct Red 253 and Direct Yellow 107/132 dyes.
The printing inks of this invention may also contain one or more fluorescing
agents
either alone or in combination with other coloring agents as described above.
A preferred
fluorescing agent is ClircodeT"" a trademark product which is owned by and
available from
Isotag Inc. of Houston, TX.
Adjuvants
The aqueous crosslinkable resin systems and inks of this invention may contain
the
usual adjuvants to adjust flow, surface tension and gloss of a cured coating
or printed ink.
Such adjuvants contained in inks or coatings typically are a surface active
agent, a wax, or
a combination thereof. These adjuvants may function as leveling agents,
wetting agents,
dispersants, defrothers or deareators, or additional adjuvants may be added to
provide a
specific function. Preferred adjuvants include fluorocarbon surfactants such
as FC-430,a
product of the 3M company; silicones, such as DC57, a product of Dow Chemical
Corporation; polyethylene wax; polyamide wax; polytetrafluoroethylene wax; and
the like.
Aqueous Crosslinkable Printing Ink
The aqueous crosslinkable ink of this invention comprises the aqueous
crosslinkable resin system of this invention; water; and a colorant, and
optionally an
oxidative crosslinking agent. The aqueous crosslinkable ink has a pH of 7 or
greater. As
previously described, the aqueous crosslinkable resin system comprises the
water-
dispersible poly(urethane/urea); and the water-dispersible
poly(epoxy/ester/acrylate). The
aqueous crosslinkable ink of this invention may further comprise adjuvants
which function
as leveling agents, wetting agents, dispersants, defrothers, deareators, etc.
Typically, the
ink is prepared from a varnish comprising the aqueous crosslinkable resin
system of this
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WO 03/046039 PCT/USO1/46120
invention; the oxidative crosslinking agent; a non-ionic surfactant; a wax
adjuvant such as
oxidized polyethylene wax, paraffin wax, and the like; a defrother such as
dimethyl
polysiloxane, and the like; and water. The varnish is then compounded with the
colorant,
typically a pigment, and any further adjuvants and water to produce a stable
ink having a
pH of at least 7 and preferably 8 or above. Preferably, the aqueous
crosslinkable ink of
this invention comprises: about 40 wt.% to about 50 wt.% by weight of the
aqueous
crosslinkable resin system of this invention; about 5 wt.% to about 15 wt.% of
water; about
30 wt.% to about 50 wt.% of the colorant, a fluorescing agent, or a mixture
thereof; about
0.5 wt.% to about 5 wt.% of the oxidative crosslinking agent; about 1 wt.% to
about 5 wt.%
of the non-ionic surfactant; about 1 wt.% to about 7 wt.% of the wax adjuvant;
and, about
0.1 wt.% to about 2 wt.% of the defrother. The inks of this invention are
particularly useful
in flexographic printing on low density polyethylene film such as used in the
manufacture
of diapers and other such personal care products.
Method of Application
The aqueous crosslinkable resin composition may be applied to the substrate
surface as a uniform coating using any conventional coating technique. Thus
the
composition may be spin coated, bar coated, roller coated, curtain coated or
may be
applied by brushing, spraying, etc. Alternatively the aqueous composition may
be applied
imagewise to the substrate surface, for instance as a printing ink of this
invention, using
any conventional printing technique. Once the aqueous coating composition is
applied to
the substrate surface, the resulting coating or printed image is dried thus
removing
residual water, ammonia or volatile amine, and any residual processing solvent
from the
coating or ink image to initiate curing. Typically, residual water,
ammonia/volatile amines,
and any solvent is removed as the coated substrate passes through the drying
sections of
conventional coaters or printing press systems. Although not wishing to be
bound by
theory, it is theorized that during this drying step the system pH is reduced
to initiate
crosslinking between the reactive keto groups of the epoxy/ester/acrylate
component with
the terminal amino functionality of the poly(urethane/urea) component to form
a cured film
or ink image. In a dual crosslinking mode, the cured film or ink image is
further cured by
oxidative crosslinking of the residual ethylenic groups of the
epoxy/ester/acrylate
component over an extended period of time thus further hardening and adhering
the cured
film or ink image to the substrate. Regardless of the mechanism involved in
the
application or printing method of this invention, a cured film or ink image is
formed which is
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tack-free and firmly adherent to the surface of the substrate, and which is un-
blocked when
contacted under pressure to a second surface of a second substrate or another
portion of
the cured film or ink image. As used herein the term "cured film" is intended
to include a
continuous cured film composition as well as a discontinuous cured ink image
composition.
In a preferred embodiment of this invention an image is printed on a substrate
comprising the steps: printing the aqueous crosslinkable ink of this invention
(previously
described) onto a surface of the substrate to form an image; and drying the
image to
initiate curing so that the image formed which is tack-free, firmly adherent
to the surface of
the substrate, and un-blocked when contacted under pressure to a second
surface of the
substrate or a second substrate. In an added embodiment of the printing method
of this
invention, the crosslinked ink image is further crosslinked by oxidative
crosslinking of the
residual ethylenic unsaturation.
Substrate
In general, the substrate and its surface may be composed of any typical
substrate
material such as plastics, for example polyolefin, polystyrene,
polyvinylchloride,
polynaphthelene terephthalate, polyacrylate, polyacrylic, metals, composites,
glass, paper,
etc.; however, a polymeric substrate is preferred. Typically, the substrate is
a sheet
material selected from a polyolefin, metalized polyethylene terephthalate,
polystrene,
polycarbonate, polyurethane, polyesters, polyamide, polyamide, a paper product
or a
metal. Preferred polymeric substrates include a sheet of polyethylene,
polypropylene,
polyethylene terephthalate, cellulose acetate, cellulose acetate butyrate, or
polycarbonate.
Low-density polyethylene such as used in the manufacture of diapers and other
such
personal care products, is particularly preferred.
The following examples further illustrate details of this invention. This
invention,
which is set forth in the foregoing disclosure, is not to be limited either in
spirit or scope by
these examples. Those skilled in the art will readily understand that known
variations of
the conditions of the following procedures can be used. Unless otherwise
noted, all
temperatures are degrees Celsius and all part and percentages are by weight.
Example 1
An aqueous, epoxy/ester/acrylate having reactive keto groups was prepared from
the components listed in Table 1 using the procedures described herein below.
CA 02468128 2004-05-25
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Table 1
Component Wt.%
DER-661 Epoxy Resin~a~ 12.17
Pamolyn 200~b~ 3.94
Pamolyn 300~~~ 2.58
Zirconium Catalyst (12%)~d~ 0.04
Arcosolve PNP Solvent~e~ 18.15
Diacetone acrylamide 4.88
Butyl acrylate 4.88
Methacrylic acid 3.08
t-Butyl peroctoate 1.36
AIBN (Vazo 64) 0.32
n,n-Dimethylethanolamine 4.55
D.I. Water 44.05
(a) DER-661 Epoxy Resin is phenol,4,4'-(1-methylethylidene)bis-, polymer with
2,2'-{(1-methylethylidine)bis(4,1-
phenylene-oxymethylene)}bis(oxirane); a product of Dow Chemical.
(b) Pamolyn 200 is 9,12-octadecanedienoic acid (Z,Z) (CAS # 60-33-3); a
product of Herculese.
(c) Pamolyn 300 is a fatty acid mixture containing 39 %by weight linoleic
acid; 40 % by weight of linolenic acid; and 21
by weight of oleic acid; a product of Herculese.
(d) Zirconium Catalyst is zirconium 2-ethylhexoate (12% in mineral spirits); a
product of OMG Americas.
(e) Arcosolve PNP Solvent is 1-propoxy-2-propanol; a product of Arco corp.
(f) AIBN (Vazo 64) is azoisobutyronitrile ; a product of the DuPont Company
The DER-661, Pamolyn 200, Pamolyn 300 and Zirconium Catalyst Components were
charged into a reactor, a nitrogen blanket was applied and the batch slowly
heated to
150 C 2 C and held at that temperature for 0.5 hours. The temperature was
increased
to 200 C 2 C and held at that temperature for 1 hour. then increased to 234 C
2 C and
held at that temperature for 5 hours. The acid number of the reaction mixture
was then
checked and subsequently checked hourly until it was equal to or less than 5,
at which
point the batch was cooled to 125 C 2 C. When the batch had cooled heating was
restored to 134 C 2 C and the following additions were made. t-Butyl
peroctoate and
2.27 wt.% of the Arcosolve PNP Solvent were premixed and then 1 % of the
mixture was
added to the reactor through an addition funnel. After 5 minutes, addition of
the mixture
was continued and addition was started of a pre-prepared solution of the
diacetone
acrylamide, butyl acrylate, methacrylic acid and 3.4 wt.% of the Arcosolve PNP
Solvent
and continued at a reaction temperature of 134 C 2 C over a period of 2 hours
15
minutes ( 15 minutes). When monomer addition was complete, the polymerization
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grafting reaction was continued at 134 C 2 C for two hours. The amount of
solids
formed during polymerization was determined hourly, and when the amount
reached a
constant value, the batch was cooled to 80 C 2 C. The following three charges
of AIBN
were added sequentially. 0.13 wt.% of AIBN was added and polymerization
continued for
1 hour at which point the amount of solids was checked. 0.13 wt. % of AIBN was
then
added and polymerization continued for 1 hour at which point the amount of
solids was
checked. 0.06 wt. % of AIBN was then added and polymerization continued for 1
hour at
which point the amount of solids was checked. When the solids value obtained
remained
constant, the batch was cooled to 60 C 2 C. Next, N,N- Dimethylethanolamine
3.20
wt.% and 8.37 wt.% D.I. Water were premixed and the mixture was added to the
batch
over a period of 15 minutes 5 minutes. Then 25.68 wt.% D.I. water was added to
the
batch over a period of 15 minutes 5 minutes and the final product was stirred
for 30
minutes before the reactor was cooled to 40 C 5 C. A portion of
dimethylethanolamine
was then added to the batch to adjust the pH to 9.0 to 9.5; and a portion of
D.I. water was
added to adjust the viscosity to 2500 to 3500 cps. The resulting aqueous
epoxy/ester/acrylate product was then discharged through a 150 micron cloth
filter to
provide a epoxy-ester-acrylate resin solution containing about 30-35 % by
weight of the
unsaturated fatty ester of the epoxy resin grafted with a terpolymer of
methacrylic acid,
butyl acrylate, and diacetoneacrylamide.
Example 2
An aqueous, poly(urethane/urea) having terminal reactive amine groups was
prepared from the components listed in Tables 2 and 3 using the procedures
described
herein below.
Table 2
Component Wt.%
polyTHF 1000~9~ 36.85
Dimethylolpropionic acid (DMPA) 6.50
MPDioI~"~ 2.30
Jeffamine M-1000~i~ 4.85
m-TMXDI~~ 42.00
Ethyl acetate 7.50
(g) polyTHF 1000 is alpha-hydro-omega-hydroxy-poly(oxy-1,4-butyldiyl) having a
MW of about 1000; a product of BASF.
(h) MPDioI is 2-methyl-1,3-propanediol; a product of Arco.
(i) Jeffamine M-1000 is methoxypoly(oxyethylene/oxypropylene)-2-propylamine a
product of Huntsman.
Q) m-TMXDI is meta-tetramethylene xylene diisocyanate; a product of Cytec.
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DMPA, poly THF 1000, MPDioI, Jeffamine M-1000 and ethyl acetate were added to
a reactor under nitrogen. The mixture was slowly heated to 45 -55 C for at
least 30
minutes, then m-TMXDI was added. The reaction batch was slowly heated to 90 C
at a
rate of 1 degree per minute and maintained at temperatures below 100 C. When
the
temperature reached 90 - 95 C, the reaction mixture was checked for its free
NCO
content every 30 minutes. The reaction was continued for about 2 to 3 hours
until the % of
free NCO was 4.9 -5.2% at which point the reaction was cooled to 65 - 70 C.
The
resulting pre-polymer was then sampled for its % of free NCO and % non-
volatiles while
being held at 65 - 70 C.
Table 3
Component Wt.%
water 53.39
ammonia 1.55
Scav Ox Lo hydrazine~k~ 7.40
Pre-Polymer 37.66
(k) Scav Ox Lo hydrazine is a 15.5% water solution of the diamine hydrazine; a
product of Olin corp.
Water and ammonia were charged into a reactor at room temperature. Scav Ox Lo
hydrazine was added to the reactor and mixed at a temperature of 20 -30 C. The
pre-
polymer was added to the reactor over a 15 minute period and the temperature
increased
to 40 -45 C and maintained below 45 C. After all transfers were complete, the
mixture
was held at 40 C for 1 hour to form a poly(urethane/urea). The batch contained
36% by
weight solids, had a viscosity of about 300 cps, a pH of about 9, and had an
Amine Value
of 35. This polyurethane-urea) was believed to be propanoic acid, 3-hydroxy-2-
(hydroxymethyl)-2-methyl-, polymer with 1,3-bis(1-isocyanato-1-
methylethyl)benzene,
hydrazine, -hydro- -hydroxypoly (oxy-1,4-butanediyl) and 2-methyl-1,3-
propanediol,
ammonium salt, polyethylene-polypropylene glycol 2-aminopropyl methyl ether
blocked.
Example 3
An aqueous crosslinkable resin varnish was prepared from the
epoxy/ester/acrylate
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WO 03/046039 PCT/USO1/46120
resin of Example 1 and the poly(urethane/urea) of Example 2 having the
following
formulation:
Component Wt.%
Polyurethane/urea of Example 2 28.40
Epoxy/ester/acrylate of Example 1 17.90
Oxidized polyethylene wax 4.00
Surfactant(~~ 1.00
Paraffin wax emulsion~"'~ 30.00
Dimethyl polysiloxane 2.00
Metal carboxylic salts("~ 4.00
Water 12.30
(I) Surfactant is Rhodomax LO surfactant (from Rhodia Corp.) a 30% aqueous
solution of mixed non-ionic and cationic
surfactants (CAS# 70592-80-2)
(m) Paraffin wax emulsion contains 30% by weight of paraffin wax emulsified in
water.
(n) Metal carboxylic salts is a mixture of carboxylic salts of cobalt and
manganese.
The components were mixed to produce a stable aqueous varnish dispersion
having a
viscosity of about 25 seconds using a #3 Zahn Cup.
Example 4
An aqueous crosslinkable printing ink was prepared from the varnish
formulation of
Example 3 having the following formula:
Component Wt.%
Varnish formulation of Example 3 50.00
Titanium dioxide pigment 40.00
Oxidized polyethylene wax 2.50
Water 8.00
The components were mixed to produce a stable aqueous varnish dispersion
having a
viscosity of about 25 seconds using a #3 Zahn Cup. The printing ink of Example
4 was
used in a Common Impression Flexographic printing press to print on sheets of
low-
density polyethylene. When dried the printed ink firmly adhered to the
polyethylene
without any evidence of blocking, i.e., Sticking of ink to non-printed film or
two separate ink
surfaces sticking together to form a single surface. The antiblocking
character of the ink
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and its firm adhesion to the polyethylene was further improved by oxidative
exposure to air
for 24 hours or more.
Those skilled in the art having the benefit of the teachings of the present
invention
as hereinabove set forth, can effect numerous modifications thereto. These
modifications
are to be construed as being encompassed within the scope of the present
invention as
set forth in the appended claims.
