Note: Descriptions are shown in the official language in which they were submitted.
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SUN-176 ( - )
IRECT PROCESS FOR THE PRODUCTION OF PRINTING INKS
BACKGROUND OF THE INVENTION
Printing inks are conventionally prepared by
a series of steps that comprise (1~ reacting the
starting ingredients for the pigment in an agitated
vessel to obtain a slurry containing about 1 ~o 3
percent of pigment in mother liquor, (2) filtering and
washing the liquid reaction product of step (1) with
water to remove the mother liquor and decrease the
amount of water-soluble by-products to an acceptable
level, forming a presscake that contains about 20
percent of pigment and 80 percent of water, (3) putting
the presscake from step (2) into a high horsepower,
high shear mixer for at least 15 hours to transfer the
pigment from the aqueous phase to a non-aqueous phase
to effect complete dispersion of the pigment in the
non-aqueous phase, and (4) finally adjusting the batch
by adding materials to insure proper rheology and color
characteristics to meet the requirements of the
printing ink manufacturer.
The pigment flush product from step (4) is
then sold to the manufacturer of printing inks who
then, at a different location, (5) mixes the pigment
with additional varnish, e.g., resin, solvent, and,
optionally, a drying oil, and conventional additives to
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prepare a printing ink that meets the customer's
requirements.
Alternately, the pigment presscake from step
(2) may be dried, the dry product mixed with the non-
aqueous componen~s, and the resulting paste subjected
to high shear in dispersion equipment, such as a three-
roll mill.
BRIEF DESCRI_TION OF THE INVENTION
It has now been found that a printing ink
base with improved properties can be made in less time
and at a reduced cost by a direct process that consists
essentially of the steps of (1) reacting the starting
ingredients for a pigment in an agitated vessel until a
liquid reaction product is obtained that contains about
6 to 15 percent of pigment in mother liquor, (2)
transferring the product of step (1) into a high
horsepower, high shear mixer to transfer the pigment
from the aqueous phase to the non-aqueous phase and to
reduce to an acceptable level the water-soluble by-
products, and then (3), while the material is still in
the mixer, adding the ingredients to make a base ink
that meets the customer's specifications.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a flow diagram of the
conventional process for manufacturing printing inks.
FIGURE 2 iS a flow diagram of-the process of
this invention for manufacturing printing inks.
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DETAILED DESCRIPTION OF THE INVENTION
A direct process for the production of a
printing ink base consists essentially of the steps of
~1) reacting the starting ingredients for a pigment in
an agitated vessel to obtain a product that contains
pigment in mother liquor, (2) placing the product in a
high horsepower, high shear mixer to transfer the
pigment from the aqueous phase to a non-aqueous phase,
and (3) while the material is still in the mixer,
adding the necessary ingredients to make a printing ink
base that can further be formulated into a printing
ink.
~ 1) The raw materials for making a pigment
are fed into a stri~e tank equipped with a variable
speed agitator; a source of heating generally, but not
exclusively, steam; a thermometer; and a pH probe to
establish acidity or alkalinity of the reaction. The
ingredients are mixed for 2 to 6 hours until the
reactions required for the manufacture of the pigments
are complete.
(~) The reaction product from (1),
containing 6 to 15 percent of pigment, is added to a
heavy duty mixer, such as a Baker Perkins-type flusher,
having high horsepower and high shear mixing. The
pigment is transferred from an aqueous phase to a non-
aqueous phase by the addition of a suitable printing
ink-type varnish. The varnish preferentially wets the
pigment and displaces the water which separates and is
clear and free of pigment. The separated water is
poured off, leaving ~ soft paste of pigment, varnish,
and some residual water. The viscosity of this soft
paste is gradually increased by further additions of
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pigment slurry and some varnishes as needed to aid
pigment wetting and water separation. The final
product is very heavy and stiff, requiring the
horsepower and shear of a heavy duty mixer to producé
an excellent dispersion of pigment in the chosen
varnish.
The heavy mass is washed to remove soluble
salts left from the pigment slurry. Fresh water is
added, mixed, and poured off several times until a low
conductivity value is reached. The final mass contains
pigment, varnish, and 10 to 20 percent of residual
water which can be removed under vacuum and heat or by
open mixin~ to promote natural evaporation.
Finally, the mass is reduced to press-ready
ink by the addition of more varnishes, solvents,
driers, etc.
Typical resins used in the varnishes
mentioned above include, but are not limited to,
hydrocarbons, alkyds, phenolics, modified phenolics,
rosin esters and modified rosin esters, and the like,
and mixtures thereof, in an amount between about 45 to
70 percent, and preferably between about 25 to 50
percent, based on the weight of the oils.
A drying oil may be included in order to
initially aid water breakout and to improve press
characteristics. Typical oils include alkyds, linseed,
soya, proprietary drying varnishes, and the like, and
their mixtures, in an amount between about 5 and 25
percent, and preferably between about 5 and 10 percent,
based on the weight of total varnish.
The process of this invention is "system
specificn, that is, the specific materials selected and
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the amount of each depend upon the requirements of each
customer. The amounts of the additives likewise vary
with the desired properties of the finished ink, but
generally they are used in amounts up to about three
percent, and preferably about one percent, based on the
weight of the finished ink.
The direct process of this invention is
applicable to any pigment that is used in printing
inks. Specific examples include, but are not limited
to, Mono- and Diarylide Yellows, Lithol Rubine,
Permanent Red 2B, Lithol Reds, Red Lake C, and
Phthalocyanine Blue. It may be used to produce any ink
system in which the essen~ial vehicle is immiscible
with water, such as for example offset or lithographic,
publication gravure, and some packaging gravure and
flexographic systems.
The total time that the material is in the
flusher, from when the liquid reaction product from the
strike tank is placed in the flusher until the finished
printing ink is removed for packaging, is about 6 to 12
hours.
The process of this invention may be carried
out in a continuous, semi-continuous, or batchwise
manner.
As a result of using the direct process
described herein, printing inks are obtained that have
considerably improved properties. In addition, major
economies have been effected in time, energy
consumption, and money. By increasing the amounts of
solids in the slurry made in the strike tank, there is
less effluent, making it easier to transfer the pigment
to the non-aqueous phase in the flusher and decreasing
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the amount of waste material, both liquid and solid, to
be removed.
By making the printing ink directly in the
flusher, the intermediate filtration and
standardization steps are eliminated, saving time,
money, and energy. More batches can be made in a given
time; less handling of the pigment results in
enhancement of color strength the amount of raw
material required is less than the amount required in
the conventional process to produce the same strength.
The end products, suitably but not
necessarily, offset or lithographic inks, are superior
to inks made by the conventional process in properties
such as color strength, gloss, transparency,
cleanliness of hue, and dispersibility, and the quality
of the ink product is consistent.
The process of this invention will be Eurther
illustrated by the following examples wherein all parts
and percentages are by wei~ht unless otherwise
specified.
Example 1
Pigment Yellow 12 slurry was prepared as
follows:
1. To 2400 parts of ice in a make-up tank
was added 680 parts of hydrochloric acid (35.5% or
20Bé), followed by the addition of 350 parts of
dichlorobenzidine 100% (as the dihydrochloride~. The
slurry was stirred for 30 minutes and then cooled down
by the further addition of 1700 parts of ice to a
temperature of 0 to -5C. To this was added 10 parts
of chelating agent. The s~urry was stirred for 10
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minutes at 0 to ~5C. To the cold slurry 532 parts of
a 38.5~ solution of sodium nitrite was added over 2 to
4 minutes. The reactants were stirred for 30 minutes
to form the tetrazo of dichlorobenzidine; an excess of
nitrite was maintained throughout. The tetrazo so
prepared was then added to a strike tank containing
1000 parts of ice.
To 1600 parts of ice was added 500 parts of a
50 percent solution of sodium hydroxide, followed by
the addition of 580 parts of a 70 percent solution of
acetic acid. The mixture was stirred for 15 minutes,
and then 525 parts of acetoacetanilide was added. The
slurry so obtained was stirred for 30 minutes, and then
30 parts of a surface active agent was added.
The acetoacetanilide slurry was then cooled
to 8 to 10C. by the further addition of 1050 parts of
ice. The pH of the slurry was 6.1 to 6.7 at 8 to 10C.
The excess nitrite in the tetrazo was
destroyed by the addition of 16 parts of sulfamic acid.
The acetoacetanilide slurry was added to the
tetrazo in the strike tank in less than 20 minutes.
The yellow brown suspension obtained in the strike tank
was stirred for 30 minutes to complete the reaction.
The temperature was 8 to 12C~ throughout and the pH of
the slurry after the reaction was 2.6 to 3.3. The
yellow-brown slurry was then heated to 45~C. with
direct steam, and 450 parts of a 50 percent solution of
sodium hydroxide was added to adjust the pH of the
slurry to 10~1 to 10.3. During the heat-up the slurry
became cleaner and more yellow than yellow-brown.
To the above slurry was added 73 parts of the
sodium salt of rosin dissolved in 250 parts of water at
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50C. The slurry was stirred for 5 minutes and then 37
parts of an inorganic salt was added. The slurry was
stirred for 10 minutes more at 45 to 50C. The final
pH of the slurry was 6 to 6.5 with a temperature of 45
to 50C. The slurry containing 8 to 10 percent of the
yellow organic pigment was then available for addition
to the high horsepower/high shear mixer.
2. To a Baker-Perkins high horsepower, high
shear flusher were added 383 parts of the Yellow 12
strike tank slurry containing 8.7 percent of pigment
(33 parts) and 66 parts of a quickset vehicle at 26 to
27 poises viscosity. The mixture was warmed to 50 to
60C., and mixing was continued until the water
separated and the oil-pigment phase collected together
(approximately 30 to 60 minutes). The clear water was
poured off. The oil phase was very soft.
Then 191 parts of Yellow 12 slurry (17 parts
of pigment) was added, and mixing was continued until
the water separated and the oil-pigment phase collected
together (approximately 30 minutes). The mass was
considerably heavier.
Then 191 parts of the Yellow 12 slurry (17
parts of pigment) was added, and mixing was continued
until the water separated and the oil-pigment phase
collected (approximately 15 to 20 minutes). The mass
was very stiff. A total of 83 percent of water had
been poured off The mass was washed by adding 1500
parts of fresh tap water, mixing for 5 minutes, and
then pouring off the water. This was done a total of 4
times. The conductivity before the washing was 7.554 x
10,000 mhos and after the washing it was 6.94 x 1,000
mhos.
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The final washed mass consisted o 50 percent
of pigment, 50 percent of ~arnish, and residual water.
This mass was mixed with 79 parts of quickset
vehicle, 2 parts of an anti-skinning agent, and 3 parts
of a hexyl carbitol softening agent, resulting in 216
parts of a base ink.
A final cut back was made by mixing the 216
parts of base ink with 400 parts of gelled quickset
varnish, 66 parts of a wax compound, 42 parts of
petroleum distillate (boiling average 535F.), 50 parts
of petroleum distillate (boiling average 470F.), and
59 parts of water, resulting in 833 parts of a press-
ready printing ink containing 8.0 percent of pigment.
Example 2
The procedure of Example 1 was repeated with
each of the following pigments instead of Pigment
Yellow 12: Lithol Rubine, Permanent Red 2B, Red Lake
C, and Phthalocyanine Blue. The results were
comparable.
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