Note: Descriptions are shown in the official language in which they were submitted.
~115871
1 This invention relates to improved lithographic
printing ink compositions and to a method for preparing
them. More particularly, the invention relates to bleed-
resistant inks containing an azo red pigment.
In the lithographic printing process, the printing
plate is prepared by a selective etching process so that
the image-producing area is water-repellent and the non-
image area is water-absorbent. The surfaces of said areas
are even with respect to each other, in the case of a flat
plate, for example, the surfaces lle in the same plane.
Prior to the applicatlon of the ink to the plate, an
aqueous solution known as a fountain solution is distributed
across the plate but it is adsorbed preferentially by the non-
image area. The printing ink is re~ected by the wetted area
and thus only the desired image is reproduced when the plate
is pressed against the paper or other material belng printed.
A lithographic ink is principally a concentrated dis-
persion of a pigment in a viscous oil vehicle plus a hydro-
carbon solvent. The principle underlying lithographic
printing is the old adage, "oil and water do not mix." Much
of the difficulty encountered in lithographic printing, how-
ever, originates from the fact that lithographic inks do mix
with the fountain solution to some extent depending on the
vehicle and pigment in the ink and the properties of the
fountain solution. The repeated intimate contact of the ink
with the fountain solution on the printing plate tends to
; cause the pigment to be leached from the ink by the a~ueous
fountain solution. Such transfer of the pigment is known
as "bleeding in the fountain."
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~115871
1 Lithographic inks are, therefore, a special class of
printing inks and their ingredients must be selected care-
fully to minimize emulsification during intimate contact
with water and to maxlmize the coating of the pigment by the
vehlcle. The structure and, therefore, the properties of
the pigment are particularly important considerations when
lithographic inks are formulated. Some pigments are such
notorlously bad bleeders that their use in lithographic inks
is avoided unless there is no satisfactory substitute to
provide the particular color desired. Azo red pigments are
among these.
Two United States patents teach methods for reducing
the bleeding of pigments from lithographic inks. Both
methods are multi-step procedures and both depend on a heat-
treating step to form a coating on the pigment. U.S. 2,742,375
teaches a method comprising the coating of pigment particles
with a high molecular weight pyridinium chloride by slur-
rying the pigment in an aqueous dispersion of the pyridinium
chloride, filtering off the treated pigment and drying it
and then, as an essential feature of the method, heatlng
the dried pigment to develop a hydrophobic, organophilic
coating on the pigment.
U.S. 2,683,702 teaches a method for improving the re-
sistance of ultramarine blue and peacock blue pigments to
bleeding in a lithographic fountain solution which comprises
coating the pigment with a mixture of an alkylated methylol
melamine and an N-alkylol fatty acid amide, or with a low
molecular weight condensate thereof, by slurrying the pig-
ment in an aqueous dispersion of said mixture or condensate,
drying the treated pigment and curing such coating com-
position at an elevated temperature.
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1115871
1 The use of amine salts and quaternary ammonium salts,
each having at least one long chain aliphatic residue, as
plgment flushing aids ls taught in U.S. 2,192,954. The
flushlng ald must be a water-soluble salt and is added to
the water phase of a pigment either as the salt or, when the
water contains a sufficient amount of free acid to form a
soluble salt of the amine, as the free base. A related
patent, U.S. 2,192,956, characterizes the action of the
salts in the '954 patent as a coating of the pigment with a
hydrophobic layer. The invention disclosed and claimed in
the '956 patent, on the other hand, is the use of said salts
as flocculation aids in the washing and filtering of aqueous
slurries of pigments.
Various other treatments of pigments and printing inks
are known in the pigment art. U.S. 3,244,734 teaches that
stearamides are used as adheslon, anti-block, antl-tack, and
viscoslty-control additives in printing lnks. The vlscoslty,
adheslon, tack and blocklng propertles of an lnk are at-
trlbutes of the vehlcle rather than of the pigment and there
is no correlation between such properties and the bleeding
of lithographic inks. Moreover, it has been found that
stearamide has no effect on the tack or blocklng properties
of a lithographic printing ink, thus pointing up the special
nature of this class of printing inks.
The full development of a pigment's color in thermo-
plastic and thermoset resins is ach~eved by coating the
pigment particles with a melted fatty acid amide, according
to U.S. 3,953,218. Extremely high pigment loadings are
also said to be obtained. The patent teaches that the su-
perior wetting action of the amide permits the formulation
of resin compositions in which the amide-coated pigments
1115871
1 are highly dispersed. The properties of molded and cast
resins are discussed but the effect of water on the resins
is not discussed.
U.S. 3,905,825 teaches the treatment of azo-acyl-
acetaryl pigments with heterocyclic amines having a long
aliphatic chain attached to the ring or with aliphatic
diamines which are precursors of such heterocyclic amines.
The azo-acyl-acetaryl pigments are exemplified by Yellow
Pigment Nos. 12 and 13. The treated pigment is taught to
be easily dispersed in organic media and to be advantage-
ously useful in rotogravure inks. Bleeding in the fountain
is not a problem with such pigments, however. Almost no
bleeding occurs when a lithographic ink containing Yellow
Pigment No. 12 is contacted with a fountain solution. No
difference in bleeding is observed when the yellow pigment
is treated with a wetting agent according to the method
described and claimed hereinbelow.
The 1825 patent refers to two other patents, Brltish
Patent No. 1,080,115 and French Patent No. 1,538,270, for
their teaching about the treatment of pigments with certain
amines to make them easily dispersible. The French patent
also relates to azo-acyl-acetaryl pigments. The British
patent teac~es the treatment of organic pigments, including
azo red pigments, with amine salts in the presence of water.
A possible explanation of the improved dispersibility of
pigments so treated, as offered by the patentee, is that
there is a transfer (~lushing) of the pigment from the
aqueous phase to the amine phase. The patentee teaches that
aqueous suspensions of pigments may be treated simultaneously
with the amine and resins such as wood rosin and maleinized
IllS871
1 natural resins.
Cycloaliphatic amlnes are taught in U.S. Patent No.
3,573,946 as agents for treating either dry pigments or
aqueous suspensions of pigments in order to make said
pigments more dispersible in organlc or aqueous media.
The coating of pigments with a special cationic
surface-active combination of a quaternary ammonium com-
pound and a tertiary aliphatic amine containing up to
ten ethoxy groups is ~aught in U.S. Patent No. 3,014,810.
The treatment is said to enhance dispersion of the pig-
ments in organophilic media, e.g., oil systems, and oleo-
resinous materials. The coating of the pigment may be
accomplished by adding the special surface-active agent
to the organophilic media and then adding a dry pigment
to said media or by flushing a water-wet pigment cake
with said media.
Printing inks and varnishes whose components comprise
amine salts of acidic resins and of acidic modifled drylng
olls are taught ln U.S. 3,412,053. Sald amlne salts are
miscible with water-soluble organic solvents but the acidic
resins and drying oils from which they are made are not
miscible with such solvents. Decomposition of the amine
salts after deposition of the printing ink on paper causes
the precipitation of the insoluble binders.
Now, it has been discovered that lithographic printing
ink compositions containing an azo red pigment and at least
one lithographic vehicle selected from the class consisting
of an aromatic petroleum hydrocarbon, an alkali refined
linseed oil, a pentaerythritol ester of phenolic modified
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~115871
rosin, a heat-bodied linseed oil, and a pentaerythritol ester
of maleic modified rosin are made resistant to bleeding of
the pigment into the fountain solution by mixing the ink
vehicle and pigment with at least one pigment wetting agent
selected from the class consisting of:
an aliphatic monoamine having from 2 to about 20
carbon atoms;
an aliphatic polyamine having from 2 to about 36
carbon atoms wherein the ratio of carbon atoms to
amino groups is from about 1 to about 18,
an amine oxide having the formula
~Rl
R_ N ~ 0
R2
wherein R, R' and R2 are aliphatic groups having from
1 to about 20 carbon atoms but wherein the total
number of carbon atoms is about 36 or less;
dehydroabietylamine or tetrahydroabietylamine;
an amide having the formula
0
R3- N - C - R4 II
H
wherein R3 is an aliphatic group containing from about
12 to about 20 carbon atoms and R4 is an aliphatic
group containing from 1 to about 7 carbon atoms;
an amide having the formula
o
R~ - C - NR6R7 III
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1115871
1 wherein R~ is an aliphatic group having from about 12
to about 20 carbon atoms and R6 and R7 are indepen-
dently hydrogen, lower alkyl, or lower aminoalkyl;
an amide having the formula
O / (R9 - O)~ H
R3 - C - N IV
\ (Rl- O)~ H
wherein R3 is an aliphatic group having from about 12
to about 20 carbon atoms, R9 and Rl are alkylene
groups having from 2 to about 4 carbon atoms, m is
from 0 to about 5 and n is from about 1 to about 5
but m + n i8 from about 1 to about 5,
an amidine having from about 12 to about 20
carbon atoms;
an amidoxime having from about 12 to about 20
carbon atoms;
an oxime having from about 12 to about 20 carbon
atoms;
an oxazolidine having the formula
Rll - N O V
wherein ~1l is a polyacrylate residue having a molec-
ular weight of from about 800 to about 3000;
an amino acid having the formula
Rl2 - CH(NRl3) - (CH )p - COOH VI
wherein Rl 2 iS an aliphatic group containing from about
12 to about 20 carbon atoms, Rl 3 iS independently hy-
drogen, methyl or ethyl, and p is from 0 to about 4;
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~115871
1 an N-acyl amino acid having the for~ula
o Rl~
Rl 4 _ C - N - CH - COOH VII
W}!ereill Rl 4 iS an alkyl group having from about 12 to
about 20 carbon atoms and Rl' is an alkyl group having
from 1 to about 4 carbon atoms;
an alkyl imidazoline having the formula
N - CH
R 16 C VIII
N ~ ( ~H 2
[(CH2)X - O]y H
wherein Rl 6 iS an alkyl group having from about 12 to
about 20 carbon atoms, x is from 2 to about 4, and y is
from 0 to about ~; and
an aliphatic substituted aniline or naphtylamine
wherein the aliphatic substituent contains from about
6 to about 20 carbon atoms.
Saltæ of the foregoing amines with organlc and in-
organic acids are also useful. The salts of lower alkyl
carboxyllc acids are preferred.
The term "aliphatic" is used in the description of
this invention herein to mean a hydrocarbon group. Thus,
for example, an aliphatic monoamine is an amine having a
hydrocarbon group attached to the nitrogen atom and there
are no other substituents on the hydrocarbon chain.
~epresentatives of the azo red pigment include tol-
uidine red, chlorinated para red, permanent red 2B, lithol
rubine red, red lake C, lithol red, Molora red and Macatawa
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1115871
1 red. Molora and Macatawa trademarks of ~hemetron Corp-
poration for the manganese and calcium salts, respectively,
of the diazo couple from C-amine and ~-hydroxy naphthoic
acid.
The composition and properties of the lithographic
vehicles which may be employed in the method and com-
positlon of this invention are well known in the printing
and pigment arts. Included among such vehicles are
aromatic petroleum hydrocarbon resins, alkali-refined
linseed oil, pentaerythritol esters of phenolic-modified
rosins, maleic acid-modified rosin esters and mixtures
thereof with each other and with tung oil.
The amount of pigment wetting agent which is effective
to impart bleed resistance varies somewhat depending upon
the particular agent employed but it is generally within the
range of from about 0.5% to about 60% based on the weight
of the pigment. The effective amount of the various types
of agent is as follows:
aliphatic monoamines and salts thereof - from
about 0.5% to about 25%, preferably from about 0.75
to about 12%; amounts ranging from about 1.5~ to
about 12% are especially effective;
aliphatic polyamines and salts thereof - from about
0.5% to about 25%, preferably from about 1% to about12%;
aliphatic substituted aniline or naphthylamine
and salts thereof - from about 1% to about 20%, pre-
ferably from about 2% to about 15%;
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1115871
l dehydro - and tetrahydroabietylamine and salts
thereof - from about 3% to about 30%, preferably from
about 5% to about 25% and especially from about 12%
to about 25%;
amides of formula II, III or IV - from about 4%
to about 12%, preferably from about 5% to about 10%,
especially from about 6% to about 9%;
amine oxides - from about 1% to about 25%, pre-
ferably from about l to about 12%;
amidines - from about 4% to about 15%, prefer-
ably from about 6% to about 10%;
amidoximes - from about 4% to about 15%, prefer-
ably ~rom about 6% to about 10%;
oximes - from about 4% to about 15%, preferably
from about 6% to about 10%;
oxazolidines - from about 3% to about 60%, pre-
ferably from about 4% to about 36%, more preferably
from about 6% to about 25%;
amino acids of formula VI - from about 4% to about
12%, preferably from about 5% to about 10%;
N-acyl amino acids of formula VII - from about 4%
to about 12%, preferably from about 5% to about 10%,
imidazolines of formula VIII - from about 1.5% to
about 5%.
An aliphatic monoamines may be primary, secondary or
tertiary amines and the carbon chain thereof may be straight
or branched, saturated or unsaturated. Examples of such
amines include ethylamine, isopropylamine, butylamine,
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. .
lil5871
octyla~.ine, N, N-diethyl propylamine, decylamine,
n-dodecylamine, n-octadecylamine, hydrogenated di-tallow
amine, N, N-dimethyl dodecylamine, di-dodecyl amine, N,
N-diethyl octadecylamine and the like. Amines having f~om
about 12 to about 20 carbon atoms are preferred, particul-
arly the primary amines having such chain lenghts.
The polyamines, likewise, may contain straight-or
branched-chains. Included among examples of such amines
r A / 4 -o/;q~ "to b~ t~ne,
are N-methyl ethylenediamine, ~, diaminobuta~e, 1, 12-
diaminododecane, N-oleyl-l, 3-diaminopropane 3 triethylene-
tetramine, and diamines derived from dimer acids. Several
of the last-mentioned diamines are available from Humko-
Sheffield Chemical under the trademark Kemamine. The
preferred polyamines have a carbon atom/amino group ratio
of from about 12:1 to about 18:1. Polyamines having from
about 24 to about 36 carbon atoms are preferred especially.
The aliphatic substituents in the operative anilines
and naphthylamines of this invention are ring substituents
including such groups as dodecyl and dodecenyl. Mixtures
of alkylated anilines in which some of the side chains are
unsaturated are prepared by alkylating nitrobenzene with
a~
commercial mixtures of long olaim olefins and hydrogenating
the resulting alkylated nitrobenzene. Such olefin mixtures
are available in various cuts such as C10-Cl2, C12-C16,
C16-C18 and so on. It is preferred that the ring sub-
stituent have from about 10 to about 20 carbon atoms.
Amides prepared from a fatty amine and a lower ali-
phatic carboxylic acid are represented by formula II and
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1115871
1 are exemplified by N-octadecyl acetamide, N-lauryl propion-
amide and the like.
Stearamide, N, N-dimethyl oleamide, lauramine, N-methyl
palmitamide and N, N-dimethylaminopropyl oleamide are among
the amides represented by formula III that are contemplated
for ùse ln the method of this invention.
Ethoxylated amides of fatty acids are the preferred
compoùnds represented by formula IV. Among such compounds
are N, N-di(hydroxyethyl) amides of oleic acid, lauric acid
and myristic acid and polyethoxylated amides such as those
available from Emery Industries, Inc. under its Emid trade-
mark. Expecially preferred are thos having from about 1 to
about 3 ethoxy groups.
A resin available from Rohm & Haas under its product
designation QR 568 is representative of the oxazolidine of
formula V. Such compounds are preferred wetting agents
in the method and composition of this invention.
N-Coco aminobutyric acid, a product sold by Armak under
its trademark Armeen and designated Armeen Z is an example
of the amino acids of formula VI contemplated in this
invention.
An N-oleyl sarcosine sold by Ciba-Geigy under the
trademark Sarkosyl 0 exemplifies the amino acids of formula
VII.
An ethoxylated oleic imidazoline sold by Ciba-Geigy as
Amine 0 is an example of the imidazolines of formula VIII.
The wetting agent is incorporated into the litho-
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~15871
1 graphic lnk compositions of this invention by adding the
agent to the flushed color at or near to the end of the
dispersion process, l.e., when the flushed color is sub-
stantially dry. In this context, "substantially dry" means
0.5% or less water. It is especially preferred to add the
wetting agent during the let down step of the dispersion
process.
The treatment of the pigment vehicle dispersion with
the wetting agent does not require any heating but heat may
be applied to evaporate residual water in the flushed color
to the deslred level. The mlxing time is not critical.
The compositions contemplated in this invention are
resistant to bleeding into so-called "regular" fountain
solutions and alcoholic fountain solutions. A "regular"
solution is essentially an acidic solution of gum arabic
in water. Phosphoric acid is often used to ad~ust the pH
of the solution and various surfactants and etching com-
pounds may be present, also. The alcoholic solutions
contain up to about 40~ isopropyl alcohol in addition to
the components of the "regular" solutions.
The solvents used in formulating the inks of this
invention are aliphatic hydrocarbon solvents having a
kauributanol value of from 23 to 30 and a distillation
range from 380F. to 600F. The in~s may also contain waxes
such as a polyethylene wax, anti-oxidants and various other
additives.
The following examples illustrate the method of this
invention and also demonstrate the advantage of the com-
positions of this invention.
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~11587~
EXAMPLE l
A ~acatawa red presscake weighing 337 grams and con-
talning 91 grams of the dry plgment is flushed with 72 grams
Or a lithographic grade hydrocarbon varnish (60% solids).
Upon completion of the phase transfer, the flushed color
i8 heated under a reduced pressure to about 200F. until
0.5% or less water remains. The temperature is then lowered
to about 150F., the pressure is allowed to return to
atomspheric and 132 grams Or hydrocarbon resin, 5 grams of a
. solution Or an antioxidant (2,6-di-t-butyl-4-methylphenol)
and 3 grams Or octadecylamine are added ln a letdown
operation.
A mixture of 2 grams of the resulting product, 1.6 grams
Or oleoresinous varnish and 0.4 gram of a polyethylene wax
is then tested for its bleed resistance by shaking it wlth
12 mls. of Dahlgren fountain solution in a one ounce ~ar
on a Red Devil shaker for three minutes. The fountain
~olution is filtered and the color of the filtrate is then
checked visually for evidence of bleed. On a scale of O to
5 in which O means no bleed and 5 means severe bleed, the
filtrate is rated 0.5 whereas a control sample containing
no wetting agent is rated 4.5.
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~15871
1 EXAMPLE 2
The general procedure of Example 1 is repeated except
that 15 grams of the hydrocarbon resin is replaced in the
flushing step with Triple 0 Litho varnish and the Macatawa
red i8 replaced by Lithol Rubine to give a lithographic
lnk having a bleed resistance similar to that of the product
of Example 1.
Similar results showing the advantageous bleed re-
sistance of the compositions of this invention are obtained
when the various other wetting agents and vehicles dis-
closed herein are employed according to the method of this
invention. A rating of about 3.0 for the fountain solutlon
after intimate contact with the lithographic ink is con-
sidered to be the maximum acceptable bleed for the com-
positions of this invention and that rating is consistently
better than the untreated ink.
Inks prepared according to this invention have printing
properties which are equal to those of control inks which do
not contain the pigment wetting agents.
While the invention has been described with reference
to cerkain specific embodiments, lt will be recognized by
those skilled in the art that many variations are posslble
without departing from the spirit and scope of the invention
claimed herein.
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