Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR MANUFACTURING PIGMENTARY QUINACRIDONES
FIELD OF THE INVENTION
This invention relates to an economical continuous process
for the preparation of quinacridone pigments having uniform
particles of a narrow particle size distribution.
BACKGROUND OF THE INVENTION
Processes for the preparation of quinacridone pigments are
known, e.g., S. S. Labana and L. L. Labana, "Quinacridones" in
Chemical Review, 67, 1-18 (1967), and U.S. Patent Nos.
3,157,659, 3,256,285, and 3,317,539. The quinacridones thus
obtained are known as crude quinacridones and are generally
unsuitable for use as they must undergo one or more additional
finishing steps to modify their particle size, particle shape,
or crystal structure to achieve pigmentary quality.
A preferred method for preparing quinacridones involves
thermally inducing ring closure of 2,5-dianilinoterephthalic
acid intermediates, as well as known aniline-substituted
derivatives thereof, in the presence of polyphosphoric acid
(e. g., U.S. Patent No. 3,257,405) or even sulfuric acid (e. g.,
U.S. Patent No. 3,200,122 and European Patent Application
863,186). After the ring closure step is complete, the melt
intermediate is drowned by pouring it into a liquid in which the
crude quinacridone is substantially insoluble, usually water
and/or an alcohol. The resultant crystalline quinacridone
pigment is further conditioned by solvent treatme°nt or milling
in combination with solvent treatment.
The final particle size of a quinacridone pigment can be
controlled by methods used in both the synthesis and
aftertreatment steps. For example, quinacridone pigments can be
made more transparent by reducing their particle size or more
opaque by increasing their particle size. In known methods,
particle size is generally controlled during precipitation of
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the pigment by drowning or during the milling or solvent
treatment of the crude. The tinctorial strength and transparency
of a pigment can also be affected by solvent treatment.
Aftertreatment steps that manipulate the crude's particle size
are often referred to as conditioning methods.
Although prior art methods can produce quality products, a
more efficient process for manufacturing pigmentary quinacridone
pigments would be desirable.
SUMMARY OF THE INVENTION
This invention relates to a process for the preparation of
quinacridone pigments comprising
(a) preparing a reaction mixture by mixing
(i) a 2,5-terephthalic acid or ester thereof, and
(ii) at least about 0.5:1 to about 10:1 parts by
weight of said acid or ester of a dehydrating agent;
(b) processing the reaction mixture through a heated
kneader or continuous reactor having one or more heated zones at
a temperature of about 80 C to about 300 C;
(c) mixing of the crude quinacridone composition with a
liquid in which the quinacridone is substantially insoluble
(continuous stream of the liquid can be used for continuous
process) at a ratio of about 0.5 to about 15 parts by weight of
the liquid per part by weight of the crude quinacridone
composition;
(d) optionally, conditioning the resultant quinacridone
pigment; and
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(e) optionally, blending the resultant quinacridone pigment
with one or more quinacridone derivatives.
Other objects and advantages of the present invention will
become apparent from the following description and appended
claims .
DETAIZED DESCRIPTION OF THE INVENTION
Quinacridone pigments (by which is meant unsubstituted
quinacridone, quinacridone derivatives, and solid solutions
thereof) are prepared according to the invention by ring-closing
2,5-dianilinoterephthalic acid intermediates, including known
derivatives that are substituted in the aniline ring, by heating
such terephthalic acid intermediates and derivatives in the
presence of a dehydrating agent (preferably polyphosphoric
acid). The quinacridone is then drowned in a batch and
optionally in a continuous process. The quinacridone pigment is
preferably also subjected to additional conditioning steps to
improve pigmentary properties and, if desired, blended with an
additional quinacridone derivative.
The process of the invention is used to prepare either
unsubstituted or substituted quinacridone derivatives, depending
on whether the ring closure is carried out using unsubstituted
or substituted 2,5-dianilinoterephthalic acid (or esters
thereof) 2,5-dianilinoterephthalic acid derivative (or esters
thereof) having one or more substituents in at least one of the
two aniline rings. Although essentially any substituted
2,5-dianilinoterephthalic acid derivatives known in the art can
be used, particularly preferred substituted
2,5-dianilinoterephthalic acid derivative are known in which
both aniline moieties are substituted (typically with the same
substituent) at the para position with, for example, a halogen
(preferably chlorine), C1 -C6 alkyl (preferably methyl), and Cl
-C6 alkoxy (preferably methoxy). It is also possible to use
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2,5-dianilinoterephthalic acid derivatives in which both aniline
moieties are substituted in the para, ortho or meta positions.
Examples of suitably chloro, methyul and methoxy substituted
2,5-di(para, ortho and meta) anilinoterephthalic acid
derivatives include 2,5-di(4-chloroanilino)terephthalic acid,
10~ 2,5-di(4-methylanilino)terephthalic acid,
2,5-di(4-methoxyanilino)terephthalic acid.
It is also possible to use mixtures containing
2,5-dianilinoterephthalic acid and one or more derivatives
thereof or mixtures containing two or more
2,5-dianilinoterephthalic acid derivatives. The use of such
mixtures provides a particularly advantageous method for
obtaining quinacridone solid solutions. Mixtures containing
2,5-dianilinoterephthalic acid and/or a derivative thereof in
combination with a fully formed quinacridone pigment (generally
in crude form) can also be used.
Preparation of the reaction mixture (i.e. the ring-closure
step (a)) is carried out by contacting the 2,5-terephthalic acid
or ester thereof with a dehydrating agent, which is particularly
a strong acid, such as polyphosphoric acid, acidic esters of
polyphosphoric acid, or sulfuric acid, e.g., U.S. Patent No.
4,758,665 and S. S. Labana and L. L. Labana, "Quinacridones" in
Chemical Reviews, 67, 1-18 (1967) is used. Polyphosphoric acid,
having a phosphate content equivalent to about 110 to 1200 H3P04
is particularly preferred. When using polyphosphoric acid,
the weight ratio of polyphosphoric acid to the terephthalic acid
intermediate is typically about 0.5:1 to about 10:1 (preferably
1:1 to 2:1). It is also possible to use about 70 to 1000
(preferably 85 to 980, more preferably 90 to 93%) sulfuric acid
as the dehydrating agent. When using sulfuric acid, the weight
ratio of sulfuric acid to the terephthalic acid intermediate is
similar to that used with the polyphosphoric acid.
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5 The components used in step (a) are preferably mixed in an
unheated reactor or reactor section or in a heated section of a
reactor, provided that when doing so the components are
adequately mixed and heated, even when the mixture is viscous.
The batch reactor is typically one with a sigma blade mixer and
an effective heat transfer jacket. The mixer blades may also be
thermostatically controlled. The reactor may be heated or
cooled to the desired temperature. The energy required to mix a
viscous mass and the exothermic nature of the reaction will
normally necessitate heating the initial reaction mixture and
then cooling it to maintain the desired temperature range.
As an alternative to batchwise methods, a continuous
process is also possible. The reaction compositions of the
current invention lend themselves to such continuous processing.
The present invention therefore also provides continuous
process for preparing and drowning quinacridones using the
smaller amounts of dehydrating agent. In addition to allowing
the use of smaller quantities of dehydrating agent, which would
lower manufacturing costs and reduce environmental impact, the
continuous process approach produces a quinacridone pigment
having a desirably narrow particle size distribution.
The continuous process reactive components can also be
mixed before introduction into the reactor. As used herein, the
term "continuous reactor" encompasses any number of reactors
through which solids, semi-solids, and melts are passed while
being heated and, optionally, while being mixed. Suitable
continuous reactors can provide good heat transfer and thorough
mixing, even with highly viscous materials. Extruders comprise
a particularly preferred type of continuous reactor. Examples
of suitable extruders include mixing screw extruders (especially
single-screw and double-screw extruders) arranged in single or
multiple stages where heating and mixing can take place. The
desired throughput rate is, of course, a factor in selecting the
capacity of the extruder.
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Regardless of the means used for mixing, in the continuous
process, the reaction mixture is passed through one or more
heated zones in which a temperature from about 80 C to about
300 C is maintained, giving rise to an initial crude
quinacridone. In general, the batch reactor reaction is
exothermic and heating within the mixture becomes particularly
pronounced once the temperature reaches about 80 C to about
120 C. The maximum temperature reached in the heated zone is
generally dependent not only on the temperature applied
externally to the reactor but also on the time during which the
reaction mixture is retained in the mixing apparatus (i.e. dwell
time) and the nature of the dehydrating agent. Other factors,
such as the viscosity of the reaction mixture and thermal
stability of the intermediate product formed, should also be
considered when selecting the reaction parameters. For example,
when using the preferred dehydrating agent polyphosphoric acid,
in a temperature range of about 100 C to about 220 C and more
preferably, from about 140 C to about 200 C. When using
sulfuric acid as the dehydrating agent, the preferred
temperature range is about 140 C to about 220 C.
Sulfonation can occur with most of the reactants and such
reaction is often undesirable. Nonetheless, in the case of
intermediates which are less susceptible to sulfonation in
forming 2,9-dichloroquinacridone, the more economical sulfuric
acid dehydration agents can be used.
For continuous processing, multistage heating is often
desirable. When using a heating apparatus with more than one
heating zone, it is generally preferable to begin the heating
process at the lower end of the temperature range, continue the
heating process at one or more intermediate temperatures, and
complete the heating process at the upper end of the temperature
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range. In a typical three-zone reactor, for example, the
reaction mixture is passed through zones maintained at
temperatures of about 90 C, about 120 C, and about 180 C.
The time during which the reaction mixture is heated in
step (b) that is the time within the batch or continuous
reactor, is preferably selected to be sufficiently long to allow
the reaction to proceed to completion but not so long as to
allow undesirable side reactions produce significant amounts of
by-product. In the preferred temperature ranges described
above, it is generally possible to achieve essentially complete
reaction within approximately fifteen minutes, and some
instances less than five minutes. The reaction time is, of
course, somewhat dependent on the reaction temperature. The
batch reactor tends to require longer residence time due to
having a less even temperature profile.
The crude quinacridone composition formed in the reactor is
drowned in step (c) by mixing it with a liquid in which the
quinacridone is substantially insoluble at a ratio of about 0.5
to about 15 parts by weight, more preferably 1 to 10 parts by
weight. This would include water, a water-miscible solvent such
as methanol or other lower aliphatic alcohols or mixtures
thereof, or water containing a dispersion of a water insoluble
solvent. Suitable drowning liquids include water and/or
water-miscible organic liquids; including, for example, lower
aliphatic alcohols, such as methanol; ketones and ketoalcohols,
such as acetone, methyl ethyl ketone, and diacetone alcohol;
amides, such as dimethylformamide and dimethylacetamide; ethers,
such as tetrahydrofuran and dioxane; alkylene glycols and
triols, such as ethylene glycol and glycerol; and other such
organic liquids known in the art. Solvents used in the water
dispersion can be aliphatic or aromatic hydrocarbons. Other
organic liquids can be used but are generally less preferred.
In the continuous process, this drowning can also take place.
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Because the dehydrating agent of step (a)(ii) is typically
strongly acidic, one can optionally include a basic liquid in
the drowning liquid in sufficient quantities to maintain an
alkaline medium. The specific liquid used for this purpose is
not critical but is generally an alkali metal hydroxide and more
preferably a sodium or potassium hydroxide.
Depending on the type of condensation reactor used and the
pressure requirements downstream from the reactor, it may be
necessary to use a separate feeder to transfer the crude
quinacridone composition from the reactor to the drowning
apparatus. With this separate feeder, the batch and continuous
process for this second stage are similar processes. It may
also be necessary or desirable to improve handling by diluting
the crude quinacridone composition with about 1 to about 20
parts of additional dilute acid, water, water miscible solvents,
or dispersion of water miscible solvents in water: all as
described above for conditioning process before being mixed with
the drowning liquid. However, the specific design of the mixing
apparatus is generally not critical as long as the desired ratio
of liquid to crude quinacridone composition is maintained.
For the batch process, adding the same dilute acid, water
or solvents to the reactor after completion can facilitate the
discharge into the conditioning equipment. These also assist in
breaking up the viscous mass.
As previously mentioned, the drowning step (c) can be
carried out batchwise by introducing the reaction mixture from
step (b) into one or more fixed volumes of the drowning liquid.
However, when step (a) is carried out as a continuous reaction,
the drowning step (c), is preferably carried out in a continuous
manner. When carrying out the drowning by a continuous process,
the drowning liquid is generally introduced as a side stream or
a centrally injected stream into the crude quinacridone product
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stream (even when using excess drowning liquid) using nozzles or
other mixing devices known in the art. Although it is possible
to use a pipe with a simple tee, it is generally preferable to
use a drowning nozzle that reduces at least one of the component
streams into one or more thin streams. It is also possible to
use other types of nozzles, such as a ring-type nozzles, in
which the crude quinacridone composition is introduced at low
pressure and the drowning liquid is introduced in thin streams
at higher pressure. The two streams can be mixed at the
entrance of a high-speed shear pump, such as a rotor-stator type
pump. Drowning can also be carried out by mixing the crude
quinacridone composition and drowning liquid in a continuous
stirred reactor or in a series of continuous stirred reactors.
Another example of a continuous drowning apparatus is a loop
reactor. When flammable liquids, such as low boiling point
alcohols, are used, the drown stream can also be mixed with
water in a continuous manner to reduce the risk of fire or
explosion during isolation.
The drowning systems described above can be used at
atmospheric or elevated pressures, although the pressure that is
actually used is somewhat dependent on the required temperatures
and the boiling points of the liquid components being used.
When the equipment is sealed and under pressure, the temperature
of the drowning medium can be greater than the boiling point at
atmospheric pressure. The liquid streams can even be mixed at
or below room temperature to help control the initial heating
that occurs during hydrolysis of the acidic reaction mass.
Furthermore, lower drowning temperatures tend to give pigments
having smaller particle sizes. On the other hand, it may be
desirable to use higher temperatures to speed up the hydrolysis
or to help increase the particle size during drowning. Because
process cycle times can also be important, for example, because
of manufacturing cost, shorter residence times in the mixing
apparatus are generally preferred.
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5 It is possible to include various known additives to the
drowning liquid. The optional additives can be any of the
customary pigment preparation additives known in the art that
serve, for example, to improve color properties, lessen or avoid
flocculation, increase pigment dispersion stability, and reduce
10 coating viscosity. Suitable additives include, for example,
dispersants or surfactants, metal salts, and various pigment
derivatives.
Suitable dispersants include anionic compounds, such as
fatty acids (such as stearic or oleic acid), fatty acid salts
(i.e., soaps such as alkali metal salts of fatty acids), fatty
acid taurides or N-methytaurides, alkylbenzenesulfonates,
alkylnaphthalenesulfonates, alkylphenol polyglycol ether
sulfates, naphthenic acids or resin acids (such as abietic
acid); cationic compounds, such as quaternary ammonium salts,
fatty amines, fatty amine ethylates, and fatty amine polyglycol
ethers; and nonionic compounds, such as fatty alcohol polyglycol
ethers, fatty alcohol polyglycol,esters, and alkylphenol
polyglycol ethers.
Suitable metal salts include various salts of alkali metals
(such as lithium, sodium, and potassium), alkaline earth metals
(such as magnesium, calcium, and barium), aluminum, transition
and other heavy metals (such as iron, nickel, cobalt, manganese,
copper, and tin), including, for example, the halide (especially
chloride), sulfate, nitrate, phosphate, polyphosphate, sulfonate
(such as methanesulfonate or p-toluenesulfonate, or even known
quinacridone sulfonate derivatives), and carboxylate salts, as
well as the oxides and hydroxides.
Suitable pigment additives include organic pigments having
one or more sulfonic acid groups, sulfonamide groups, carboxylic
acid, carboxamide, and/or (hetero)aryl-containing
(cyclo)aliphatic groups.
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If used, such additives are used in amounts ranging from
about 0.05 to 1000 by weight (preferably 1 to 30% by weight and
more preferably 1 to 10o by weight), based on the amount of
pigment.
Regardless of the nature of the drowning medium used, the
drowned pigment is obtained as a slurry that can be isolated by
various methods known in the art, such as filtration, and then
dried if desired. Other isolation methods known in the art, such
as centrifugation, microfiltration, or even simple decantation,
are also suitable. Preferred isolation methods include
continuous filtration using, for example, belt filtration,
rotary drum filtration, ultrafiltration, or the like.
Before or after being isolated, the pigment can be
conditioned, either batchwise or continuously, in an optional
step (d) using methods known in the art, such as solvent
treatment or milling in combination with solvent treatment. The
final particle size of the pigment can be controlled by varying
the method of aftertreatment. For example, the pigment can be
made more transparent by reducing the particle size or made more
opaque by increasing the particle size. Suitable milling
methods include dry-milling methods such as sand-milling,
ball-milling, and the like, with or without additives, or
wet-milling methods such as salt-kneading, bead-milling, and the
like in water or organic solvents, with or without additives.
The tinctorial strength and transparency of the pigment can
also be affected by solvent treatment carried out by heating a
dispersion of the pigment, often in the presence of additives,
in a suitable solvent. Suitable solvents include organic
solvents, such as alcohols, esters, ketones, and aliphatic and
aromatic hydrocarbons and derivatives thereof, and inorganic
solvents, such as water. Suitable additives include
compositions that lessen or avoid flocculation, increase pigment
dispersion stability, and reduce coating viscosity, such as
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polymeric dispersants (or surfactants), e.g., U.S. Patent Nos.
4,455,173; 4,758,665; 4,844,742; 4,895,948; and, 4,895,949.
During or after the conditioning step it is often desirable
to use various other optional ingredients that provide
additional improved properties. Examples of such optional
ingredients include fatty acids having at least 12 carbon atoms,
such as stearic acid or behenic acid, or corresponding amides,
esters, or salts, such as magnesium stearate, zinc stearate,
aluminum stearate, or magnesium behenate; quaternary ammonium
compounds, such as tri[(C1 -C4 alkyl)benzyl]ammonium salts;
plasticizers, such as epoxidized soya bean oil; waxes, such as
polyethylene wax; resin acids, such as abietic acid, rosin soap,
hydrogenated or dimerized rosin; Clz -C18 -paraffin-disulfonic
acids; alkylphenols; alcohols, such as stearyl alcohol; amines,
such as laurylamine or stearylamine; and aliphatic 1,2-diols,
such as dodecane-1,2-diol. Such additives can be incorporated
in amounts ranging from about 0.05 to 100% by weight (preferably
1 to 30o by weight, more preferably 10 to 20o by weight), based
on the amount of pigment.
The resultant pigment is optionally blended (preferably by
dry blending) in optional step (e) with one or more pigment
derivatives known in the art, particularly sulfonic acid,
sulfonamide, and phthalimidomethyl derivatives of quinacridones.
Although generally less preferred, such derivatives can also be
added during other steps of the claimed invention.
Compared to previously known processes, pigments prepared
according to the present invention characteristically have a
narrower particle size distribution and excellent color
properties that are particularly suited for automotive
applications.
Because of their light stability and migration properties,
the quinacridone pigments prepared according to the present
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invention are suitable for many different pigment applications.
For example, they can be used as the colorant (or as one of two
or more colorants) for very fast pigmented systems, such as
mixtures with other materials, pigment formulations, paints,
printing ink, colored paper, or colored macromolecular
materials. The term "mixture with other materials" can be
understood to include, for example, mixtures with inorganic
white pigments, such as titanium dioxide (rutile) or cement, or
other inorganic pigments. Examples of pigment formulations
include flushed pastes with organic liquids or pastes and
dispersions with water, dispersants, and if appropriate,
preservatives. Paints in which the quinacridone pigments of
this invention can be used include, for example, physically or
oxidatively drying lacquers, stoving enamels, reactive paints,
two-component paints, solvent- or water-based paints, emulsion
paints for weatherproof coatings, and distempers. Printing inks
include those known for use in paper, textile, and tinplate
printing. Macromolecular substances include those of a natural
origin, such as rubber; those obtained by chemical modification,
such as acetyl cellulose, cellulose butyrate, or viscose; or
those produced synthetically, such as polymers, polyaddition
products, and polycondensates. Examples of synthetically
produced macromolecular substances include plastic materials,
such as polyvinyl chloride, polyvinyl acetate, and polyvinyl
propionate; polyolefins, such as polyethylene and polypropylene;
high molecular weight polyamides: polymers and copolymers of
acrylates, methacrylates, acrylonitrile, acrylamide, butadiene,
or styrene; polyurethanes; and polycarbonates. The materials
pigmented with the quinacridone pigments of the present
invention can have any desired shape or form.
Pigments prepared according to this invention are highly
water-resistant, oil-resistant, acid-resistant, lime-resistant,
alkali-resistant, solvent-resistant, fast to over-lacquering,
fast to over-spraying, fast to sublimation, heat-resistant, and
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resistant to vulcanizing, yet give a very good tinctorial yield
and are readily dispersible (for example, in coating systems.
The following examples further illustrate details for the
process of this invention. The 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 parts and
percentages are parts by weight and percentages by weight,
respectively.
Example 1
105 parts of 2,5-ditoluidino-terephthalic acid (DTTA) are
mixed with 210 parts by weight of polyphosphoric acid having a
P205 content of 85.3%. The mixing is done in a sigma blade
kneader at room temperature and done so as to wet out dry
intermediate, forming a smooth magma. The magma is heated to
120 to 135 C and held, with mixing, at this temperature for 2
hours. The hot magma is hydrolyzed in a vessel containing
methanol, this ratio being 10 parts by weight methanol to 1 part
by weight 2,9-dimethylquinacridone, and stirred at high speed
for 5 minutes. The resulting slurry is then stirred for one
hour at medium speed. The resulting methanol pigment slurry is
heated under increased pressure with stirring for 4 hours at a
temperature of 120 C. The slurry is then cooled, taken to zero
pressure, then filtered and washed with water to a conductivity
of 200 microMhos. The resulting quinacridone pigment is
reslurried in water and the pH adjusted from 6.5 to 7Ø 1 part
by weight mineral spirits to 1 part by weight pigment is added
to the water slurry and is stirred for one hour. The pigment is
then filtered and washed with water to low conductivity, then
dried. The result is a magenta having a clean shade, strong
tint, and highly dispersible in polyethylene.
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Comparative Example 1
As an alternative to hydrolyzing the hot magma in methanol,
as was done in Example 1, the hydrolyzation occurs in 10 parts
by weight water to 1 part by weight 2,9-dimethylquinacridone.
10 This mixture is then blended for 5 minutes at high speed and
stirred for 3 hours. The resulting pigment slurry is filtered
and washed with water until free of acid and having low
conductivity. One part by weight pigment is reslurried in 15
parts by weight water, with 1 part 50o by weight sodium
15 hydroxide (NaOH'), 1 part mineral spirits, and 0.03 parts by
weight surfactant, and the whole is heated under increased
pressure for 5 hours at 150 C. The pigment is then cooled taken
to zero pressure, filtered, washed with water to low
conductivity, and dried. The resulting pigment is lighter,
slightly weaker and dirtier than the methanol struck product of
Example 1.
Example 2
150 parts by weight of DTTA and 150 parts by weight of
polyphosphoric acid having a P205 content of 85.30 are mixed in
' the same manner as described in Example 1. The magma is heated
to 120 to 135 C and mixed at this temperature for 2 hours.
Frictional heat is generated near the end of the 2 hour time
causing the temperature to rise to 140 to 145 C. The magma is a
very flat navy blue shade, and, upon cooling, the magma becomes
a semi-solid mass that is ground to a powder. The powder is
hydrolyzed and conditioned as in Example 1. The resulting
pigment is similar to that obtained in Example 1, but slightly
dirtier and weaker with a much yellower tint shade. The
omission of mineral spirits product has little effect on the
strength, but appears to give a lighter masstone in
polyethylene.
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Example 3
100 parts by weight of 2,5-dichloroanilino-terephthalic
acid (DCTA) are mixed with 200 parts by weight of polyphosphoric
acid having a P205 content of 85.3%. This is done batch wise at
room temperature so as to wet out the dry intermediate, thereby
forming a smooth magma. The magma is heated to 120 to 135 C and
held, with mixing, at this temperature for 2 hours. The hot
magma is hydrolyzed in methanol, this ratio being 10 parts by
weight methanol to 1 part by weight 2,9-dichloroquinacridone and
stirred for one hour at medium speed then stirred for 5 minutes
at high speed. The resulting pigment slurry is refluxed for 4
hours at 70 C. The pigment is filtered and washed with water to
a conductivity of 850 microMhos. The pigment is then reslurried
and pH adjusted to 6.5 to 7Ø The pigment is filtered, washed
with water to low conductivity, and dried.
Comparative Example 3
Using the finished hot magma obtained in Example 3, it is
hydrolyzed in 12 parts by weight water to 1 part by weight 2,9-
dichloroquinacridone and stirred for one hour at medium speed
then stirred for 5 minutes at high speed. The pigment is
filtered and washed with water to low conductivity. One part
pigment is reslurried in 15 parts by weight water, with 1 part
by weight 50o NaOH, 1 part by weight mineral spirits, and 0.03
parts by weight surfactant, and the whole is heated under
increased pressure for 5 hours at 150 C. The pigment slurry is
cooled and taken to zero pressure, filtered, washed with water
to low conductivity, and dried. The resulting pigment is
lighter and stronger when compared with the pigment from Example
3 in polyethylene.
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Example 4
100 parts by weight of 2,5-dianilinoterephthalic acid
(DATA) and 200 parts by weight of polyphosphoric acid having a
Pz05 content of 85.30 are mixed in the same manner as described
in Example 1. The magma is heated to 120 to 135 C and mixed at
this temperature for 2 hours. The hot magma is hydrolyzed in
methanol, this ratio being 10 parts by weight methanol to 1 part
by weight quinacridone and stirred at high speed for 5 minutes.
The resulting slurry is then stirred for one hour at medium
speed. This methanol-pigment slurry is heated under increased
pressure for 4 hours at a temperature of 120 C with stirring.
The pigment slurry is then cooled, taken to zero pressure,
filtered and washed with water to low conductivity, The pigment
is reslurried in water and the pH of the slurry adjusted to 7.0
to 8Ø An emulsion containing mineral spirits is added and the
slurry is stirred for 40 minutes. The pigment is filtered,
washed with water to low conductivity, and dried to give a beta
crystal quinacridone.
Comparative Example 4 (a)
As an alternative to hydrolyzing the hot magma prepared as
described in Example 4, it is hydrolyzed in 10 parts by weight
to 1 part by weight quinacridone. This is stirred for 5
minutes at high speed and then stirred for 3 more hours. The
pigment is filtered and washed with water to a conductivity of
13000 microMhos. The resulting pigment presscake is then
reslurried in 8-12 parts by weight of methanol and heated for 4
to 8 hours at a temperature of 75 to 125 C. The resulting
pigment is a gamma crystal phase quinacridone.
Example 5
150 parts of DATA and 150 parts of polyphosphoric acid
having a PZOS content of 85.30 are mixed in the same manner as
described in Example 1. The hot magma is heated to 120 to 135 C
and mixed at this temperature for 2 hours. The magma is
CA 02429050 2003-05-08
WO 02/38680 PCT/USO1/50642
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hydrolyzed and conditioned as described in Example 4, and yields
the same crystal phase pigments as described in Example 4.
The invention has been described in terms of preferred
embodiments thereof, but is more broadly applicable as will be
understood by those skilled in the art. The scope of the
invention is only limited by the following claims.
