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The invention relates to phenolic-resin-modified cyclopentadiene resins, an
improved process for the preparation thereof from natural resin acids,
cyclopentadiene compounds, phenols and aldehydes in the presence of
catalysts and also use thereof.
DE-C 24 06 555 discloses oil-soluble resins which are advantageously used
as binder resins in inks for offset printing and have good compatibility
with mineral oil. They are obtained by modification of natural resin acids
with hydrocarbon resins and phenolic resins.
In the modification step with phenolic resin, there are two possible ways
of proceeding. Either the phenolic resin is added to the hydrocarbon resin
in the form of a resol prepared in a separate stage prior to the actual
reaction. Or alternatively, the resol is prepared in situ in the
hydrocarbon resin melt from the individual components, namely the
corresponding phenol and the aldehydes, usually formaldehyde, under the
action of a catalyst.
Catalysts used for the reaction of phenol with aldehyde in the hydrocarbon
resin melt are basic compounds of magnesium, calcium or zinc. However
these catalysts have the serious disadvantage that they can only
incompletely catalyze the reaction of formaldehyde with phenols in the
melt of the product of the reaction between natural resin acids and the
cyclopentadiene resins. As a result, in the actual polycondensation of the
preliminary stage comprising hydrocarbon resin modified by natural resin
acid with the phenol/aldehyde condensation product formed in the melt of
the latter, which polycondensation is carried out at elevated temperature,
up to 30% by weight of the added but unreacted aldehyde can then distill
out of the reaction mixture together with other volatile substances. This
aldehyde then has to be either recovered by fractional distillation or
disposed of as distillate by incineration. In either case, this procedure
is uneconomical. Even at superatmospheric pressure, for example in the
range from 3 to 5 bar, the reaction does not go to completion. In
addition, there is formation of insoluble fractions which negatively
affect the resin properties.
The phenolic-resin modification customarily strives for a molecular weight
increase which causes high solution viscosities which are advantageous for
a good result in printing. However, if too much aldehyde is lost, then the
products show an insufficient molecular weight increase which manifests
itself in disadvantageous, low solution viscosities and reduced printing
performance, for example in poor absorption characteristics and
unsatisfactory drying.
For industrial implementation, it is in addition advantageous to directly
use low-molecular-weight cyclopentadiene compounds in place of the
polymeric hydrocarbon resins. It has therefore already been proposed that
resins be prepared from reaction products of natural resin acids with
cyclopentadiene compounds and modification with precondensed phenolic
resins (German Patent Application P 42 11 721). However, this process has
the disadvantage that in this variant the phenolic resins have to be
prepared in a separate process step.
It is therefore an object of the present invention to provide
phenolic-resin-modified cyclopentadiene resins directly by reaction of
natural resin acids with cyclopentadiene compounds and further reaction
with aldehydes and phenols with these reacting quantitatively.
This object is achieved according to the invention by using basic alkali
metal compounds, preferably of lithium, sodium or potassium, particularly
of lithium, as catalysts for the resol formation.
The invention accordingly provides phenolic-resin-modified cyclopentadiene
resins which can be prepared from
a) from 20 to 80% by weight of cyclopentadiene compounds,
b) from 1 to 40% by weight of natural resin acids,
c) from 1 to 60% by weight of phenols and
d) from 1 to 20% by weight of aldehydes in the presence of
e) from 0.01 to 1% by weight of basic alkali metal compounds.
The phenolic-resin-modified cyclopentadiene resins according to the
invention can be preferably prepared by reaction of from 25 to 60, in
particular from 30 to 50, % by weight of cyclopentadiene compounds, from 5
to 30, in particular from 10 to 25, % by weight of natural resin acids,
from 20 to 50, in particular from 25 to 35, % by weight of phenols, from 3
to 15, in particular from 5 to 10, % by weight of aldehydes in the
presence of from 0.05 to 0.8, in particular from 0.1 to 0.2, % by weight
of basic alkali metal compounds.
The invention also provides a process for preparing the
phenolic-resin-modified cyclopentadiene resins. This can be carried out in
a single-vessel process by simultaneously reacting the components a), b),
c), d) and e) with one another. However, it is proposed that the
components a) and b) are first reacted with one another and this reaction
product is then allowed to react with the components c), d) and e).
Suitable cyclopentadiene compounds a) are those comprising a predominant
proportion of cyclopentadiene units, such as cyclopentadiene,
methylcyclopentadiene, dicyclopentadiene and polymeric cyclopentadiene
resins. The resins are generally made up of hydrocarbon fractions having a
boiling range from 20.degree. to 180.degree. C., preferably from
30.degree. to 165.degree. C. For the purposes of the present invention, a)
are preferably liquid cyclopentadiene compounds such as oligomers of
cyclopentadiene, for example di-, tri- and tetramers obtainable by
Dieis-Alder addition and also the alkyl derivatives or cooligomers of
these compounds with, for example, methylcyclopentadiene, isoprene or
piperylene. The starting materials in question do not need to have a high
degree of purity. For example, use may be made of fractions, in particular
concentrated fractions, which are formed by thermal dimerization of a C5
fraction, this C5 fraction being obtained as byproduct in the thermal
decomposition of naphtha and corresponding petroleum fractions. In such a
dimerization, the cyclopentadiene or methylcyclopentadiene contained in
such a fraction is converted into dicyclopentadiene,
dimethyldicyclopentadiene, a dimer of cyclopentadiene and
methylcyclopentadiene, a dimer of cyclopentadiene and isoprene, a dimer of
cyclopentadiene/piperylene and other corresponding dimeric substances.
These fractions can contain further unsaturated monomers, such as
propylene, butene, butadiene, pentene, cyclopentene or cyclohexene.
So-called C9 fractions formed as byproduct in the cracking of naphtha can
also be present. These then comprise, for example, styrene,
alpha-methylstyrene, vinyltoluene, indene, methylindene or mixtures
thereof.
Suitable natural resin acids b) are, for example, rosin, tall resin acid,
wood resin, dimerized hydrogenated or polymerized rosin of any origin.
The reaction of a) with b), which is preferably carried out thermally, can
be carried out in bulk but also in the presence of inert solvents.
Suitable solvents for this purpose are, for example, aromatic hydrocarbons
such as benzene, toluene, xylenes and tetrahydronaphthalene, aliphatic
hydrocarbons such as isooctane, white spirit and also mixtures of
alkylated benzenes having a boiling range from 100.degree. to 200.degree.
C. If volatile cyclopentadiene compounds are used, the process is
preferably carried out at superatmospheric pressure because of the high
reaction temperature. This is preferably up to 10 bar. Owing to the
oxidation sensitivity of the reaction products, it is additionally
advantageous to carry out the reaction in an atmosphere of a gas which is
inert under the reaction conditions, such as nitrogen or carbon dioxide.
The reaction temperature for the reaction of components a) and b) is from
50.degree. to 300.degree. C., preferably from 100.degree. to 280.degree.
C. After the reaction is complete, the reaction products obtained can be
isolated as solids by, if desired, distilling off solvent and unreacted
monomers. Their softening point generally lies between 40.degree. and
200.degree. C., preferably between 120.degree. and 170.degree. C. However,
it is simpler to react the products obtained by reaction of a) with b)
without prior isolation with the compounds c), d) and e). This embodiment
is therefore preferred.
Suitable phenols c) are phenol, substituted phenols such as alkylphenols,
preferably those having from 1 to 12 carbon atoms in the alkyl radical,
aryl- or aralkylphenols, for example cresols such as m-cresol,
1,3,5-xylenols, isopropyl-, p-tert-butyl-, amyl-, octyl- or nonylphenol,
phenylphenol, cumylphenol, also diphenylolpropane. Suitable aryl- or
aralkylphenols or phenols which are substituted by other carbocyclic
groups are those which are obtained by addition reaction of unsaturated
monomers such as styrene, .alpha.-methylstyrene, .alpha.-chlorostyrene,
vinyltoluene, cyclopentadiene with phenols in a known manner using acid
catalysts. The predominant proportion of alkyl- or aralkylphenols allows
desired compatibilities of the reaction mixtures with aliphatic
hydrocarbons to be achieved. Preference is given to bifunctional phenols,
i.e. those phenols in which two positions ortho and/or para to at least
one phenolic OH group are free and reactive. Trifunctional phenols and
those of higher functionality are generally only used together with
bifunctional phenolic components, for example the specified alkylphenols
and/or addition products of the phenols with unsaturated monomers. Here
the at least trifunctional phenols, for example phenol or
diphenylolpropane, can also be used in a proportion of preferably up to
10, in particular up to 5, % by weight, based on the total amount of
phenols. The proportion of trifunctional phenols added allows the
solubility of the end products, in particular in aliphatic hydrocarbons,
to be controlled. On the other hand, a higher content of trifunctional
phenols can be used to increase the solubility of the products in aromatic
hydrocarbons.
Aldehyde components d) which may be mentioned are, for example, aldehydes
having from 1 to 7 carbon atoms, in particular formaldehyde in monomeric
form or various polymeric forms such as trioxane and paraformaldehyde, but
also other aldehydes such as acetaldehyde, butyraldehyde,
isobutyraldehyde, benzaldehyde or furrural. The molar ratio of phenol to
aldehyde can vary within wide limits and is, for example, at least 1:0.9
and at most 1:4, preferably from 1:1 to 1:3, in particular up to 1:2.5.
The nature and amount of the phenol/aldehyde components in the starting
mixture allow the viscosity of the end products to be conveniently
controlled. Various phenols in the form of a mixture can also be used. On
the other hand, they can also be reacted, if desired, in the form of
adducts obtained by addition of unsaturated monomers, for example the
abovementioned, to the phenols.
The reaction of c) with d) is carried out according to the invention by
reacting these compounds in a temperature range preferably from 50.degree.
to 150.degree. C., in particular from 100.degree. to 140.degree. C., in
the presence of a catalyst e) in the melt of the reaction product of a)
and b) or else a solution thereof. This reaction is advantageously carried
out under pressure, preferably between 1 and 10 bar, in particular 1.5 and
4 bar.
It is here absolutely necessary to use a catalyst e). Catalysts e) used are
preferably basic compounds of lithium, sodium and potassium, such as, for
example, the hydroxides, oxides, carbonates, hydrogencarbonates, formates,
acetates and oxalates.
Sodium and potassium compounds react c) with d) completely, but here there
can be a formation of insoluble fractions which can have a negative effect
on the resin properties. Use of lithium compounds as catalysts achieves
complete reaction of c) with d) without insoluble fractions occurring in
the resin. The use of basic lithium compounds, in particular lithium
hydroxide, is therefore particularly preferred.
After resol formation is complete, further reaction is advantageously
carried out without pressure. The reaction of the resol formed with the
hydrocarbon resin is brought about by heating to high temperatures so that
the water of reaction distills off. The reaction temperature is here
generally from 200.degree. to 300.degree. C., preferably from 240.degree.
to 270.degree. C.
The progress of the reaction to the cyclopentadiene resins modified
according to the invention is monitored by the determination of
characteristic parameters, such as acid number or viscosity, in a suitable
solvent. As soon as the desired values are reached, the reaction is
stopped by cooling to room temperature. If there are solvents in the
reaction mixture, these are advantageously removed beforehand by
volatilization, for example by distillation. However, in some cases it may
be desired to at least partially leave the solvents, in particular
aliphatic-rich mineral oils preferably having a boiling range from
240.degree. to 320.degree. C., in the products to vary the melting point
and viscosity of the resin as wished. Anything from solid through a liquid
resin/mineral oil varnish to solution is possible here.
The process of the invention makes possible the advantageous preparation of
phenolic-resin-modified cyclopentadiene resins which dissolve to give
clear solutions, by reaction of natural resin acids with
low-molecular-weight cyclopentadiene compounds, phenols and aldehydes.
The products prepared according to the invention are high-melting resins.
Such products have a melting range from 120.degree. to 225.degree. C.,
preferably from 135.degree. to 200.degree. C. They are compatible with
mineral oil having a boiling range from 240.degree. to 270.degree. C. and
an aniline point of 72.degree. C., preferably in a weight ratio of resin
to oil from at least 1:3 to 1:10. It is therefore possible to dilute
particularly high-melting products of the invention which are obtained
according to the invention, after the reaction with, for example,
aliphatic-rich mineral oils and thereby to obtain a lowering of melting
point and viscosity.
The invention further provides for the use of the phenolic-resin-modified
cyclopentadiene resins of the invention as binders.
Solutions of the products in aliphatic mineral oils can also be used as
varnishes for coatings, in particular paints and printing inks. For this
purpose, they can be readily processed with alkyd resins, driers such as
naphthenates or octoates of cobalt, zinc, manganese, lead or the like, and
pigments, also with generally up to 1% by weight of chelate-forming metal
compounds such as titanates or aluminum alkoxides to give printing-ink
binders for sheet offset printing and rotary offset printing. The
chelate-formers can aid a certain amount of gel formation to the desired
degree and thus also contribute to more rapid drying and a better lay on
the paper.
The following examples serve to illustrate the invention without limiting
it.
COMPARATIVE EXAMPLE 1
Preparation of a resin according to the directions of Patent Application P
42 11 721 (Example 2) in the presence of magnesium oxide
300 g of rosin are heated to 260.degree. C. in a 3 l pressure apparatus.
700 g of dicyclopentadiene containing 75% of cyclopentadiene units are
metered into this in the course of 2 h and the mixture is maintained for a
further 5 hours while stirring at this temperature, the pressure which had
initially risen to 9 bar dropping back to 5 bar. The melt is then allowed
to cool to 110.degree. C. 627 g of nonylphenol, 172 g of paraformaldehyde
and 2 g of magnesium oxide are then added to this cooled melt. The
apparatus is then closed and made pressure-tight and is heated to
150.degree. C. for 4 hours, a pressure of up to 4 bar being established.
The vessel is then depressurized to atmospheric pressure and flushed with
nitrogen and is heated to 260.degree. C. After 25 hours at 260.degree. C.,
the reaction is stopped. 1422 g of a brittle solid resin (79% of
theoretical) having a melting point from 155.degree. C. are obtained. A
40% strength by weight solution in a low-aromatic mineral oil of boiling
range from 240.degree. to 270.degree. C. and aniline point of 72.degree.
C. has a viscosity of 5 dPa.s. The solution is turbid, thus contains
undissolved material.
EXAMPLE 1
Preparation of a resin similarly to Comparative Example 1 in the presence
of the equivalent amount of lithium hydroxide
The procedure is as given in Comparative Example 1, magnesium oxide being
replaced by 1.2 g of lithium hydroxide. After 16 hours reaction time at
260.degree. C. 1550 g (86% of theoretical) of a brittle solid resin having
a melting point from 165.degree. C. are obtained. A 40% strength by weight
solution in a low-aromatic mineral oil of boiling range from 240.degree.
to 270.degree. C. and aniline point of 72.degree. C. has a viscosity of 80
dPa.s. The solution is clear and shows no undissolved material. The
compatibility of the resin with the mineral oil is better than 1:10.
COMPARATIVE EXAMPLE 2
Preparation of a resin similarly to Comparative Example 1 in the presence
of the equivalent amount of calcium oxide
The reaction of Comparative Example 1 is carried out with 2.8 g of calcium
oxide as catalyst. 1410 g (78% of theoretical) of a brittle solid resin
having a melting point from 155.degree. C. are obtained. A 40% strength by
weight solution in a low-aromatic mineral oil of boiling range from
240.degree. to 270.degree. C. and aniline point of 72.degree. C. has a
viscosity of 5 dPa.s. The solution is turbid, thus contains undissolved
material.
COMPARATIVE EXAMPLE 3
Preparation of a resin similarly to Comparative Example 1 in the presence
of the equivalent amount of zinc oxide
The reaction of Comparative Example 1 is carried out with 4 g of zinc
oxide. 1410 g (78% of theoretical) of a brittle solid resin having a
melting point from 155.degree. C. are obtained. A 40% strength by weight
solution in a low-aromatic mineral oil of boiling range from 240.degree.
to 270.degree. C. and aniline point of 72.degree. C. has a viscosity of 5
dPa.s. The solution is cloudy, thus contains undissolved material.
COMPARATIVE EXAMPLE 4
Preparation of a resin according to the directions of DE-C 24 06 555
(Example 3b) in the presence of magnesium oxide
600 g of Portuguese rosin and 1200 g of a cyclopentadiene resin (iodine
number 197, melting point 75.degree. C.) are melted, 600 g of
p-t-butylphenol and 100 g of xylene, 2 g of magnesium oxide and 260 g of
paraformaldehyde are added and the mixture is condensed under reflux for 4
hours. The mixture is then heated with a water separator to 200.degree. C.
in one hour and maintained at 250.degree. C. for 4 hours. The vessel is
then evacuated down to 50 mbar to remove undesirable volatiles, the
pressure set to atmospheric using nitrogen and the reaction is ended by
cooling. The yield is 2370 g (89% of theoretical), the melting point is
185.degree. C., the viscosity of a 40% strength by weight solution in
mineral oil of boiling range from 240.degree. to 270.degree. C. and
aniline point of 72.degree. C. is 40 dPa.s. The solution is cloudy, thus
contains undissolved material.
EXAMPLE 2
Preparation of a resin similarly to Comparative Example 4 in the presence
of the equivalent amount of lithium hydroxide
The procedure is as given in Comparative Example 4, magnesium oxide being
replaced by 1.2 g of lithium hydroxide. After 10 hours reaction time there
are obtained 2410 g (91% of theoretical) of solid resin which begins to
melt from 190.degree. C. The viscosity of a 40% strength by weight
solution in mineral oil of boiling range from 240.degree. to 270.degree.
C. and aniline point of 72.degree. C. is 275 dPa.s. The solution is clear
and shows no insoluble material. The compatibility of the resin with
mineral oil is better than 1:10.
COMPARATIVE EXAMPLE 5
Preparation of a resin using nonylphenol in the presence of magnesium oxide
440 g of Portuguese rosin and 1060 g of a cyclopentadiene resin (iodine
number 197, melting point 75.degree. C.) are melted, 650 g of nonylphenol,
4 g of magnesium oxide and 440 g of paraformaldehyde are added and the
mixture is condensed for 4 hours at a temperature of 130.degree. C. and a
pressure of 1.5 bar. The pressure is then set to atmospheric and the
mixture is heated to 260.degree. C. while distilling off volatile
components. After 16 hours, the reaction is ended by cooling the mixture.
The yield is 1632 g (63% of theoretical), the melting point is 125.degree.
C., the viscosity of a 40% strength by weight solution in mineral oil of
boiling range from 240.degree. to 270.degree. C. and aniline point of
72.degree. C. is 2.5 dPa.s. This resin solution is slightly turbid, thus
contains undissolved material. To determine the formaldehyde content, the
distillate is admixed with aqueous hydroxylamine hydrochloride solution,
the liberated hydrochloric acid is back-titrated with potassium hydroxide
solution and from the amount used the formaldehyde content is determined.
About 110 g of formaldehyde are found in the distillate. Thus, 25% by
weight of the amount of formaldehyde used have escaped from the reaction
mixture.
EXAMPLE 3
Preparation of a resin similarly to Comparative Example 5 using the
equivalent amount of lithium hydroxide
440 g of Portuguese rosin and 1060 g of a cyclopentadiene resin (iodine
number 197, melting point 75.degree. C.) are melted, 650 g of nonylphenol,
2.8 g of lithium hydroxide and 440 g of paraformaldehyde are added and the
mixture is condensed for 4 hours at a temperature of 130.degree. C. and a
pressure of 1.5 bar. The pressure is then set to atmospheric and the
mixture is heated to 260.degree. C. while distilling off volatile
components. After 16 hours, the reaction is ended by cooling the mixture.
The yield is 2305 g (89% of theoretical), the melting point is 155.degree.
C., the viscosity of a 40% strength by weight solution in mineral oil of
boiling range from 240.degree. to 270.degree. C. and aniline point of
72.degree. C. is 85 dPa.s. The resin solution is completely clear and
shows no insoluble material. The compatibility of the resin with mineral
oil is better than 1:10. To determine the formaldehyde content, the
distillate is admixed with aqueous hydroxylamine hydrochloride solution,
the liberated hydrochloric acid is back-titrated with potassium hydroxide
solution and the formaldehyde content is thereby determined. The
formaldehyde content is below 0.1%.
EXAMPLE 4
Preparation of a resin similarly to Comparative Example 5 using the
equivalent amount of sodium hydroxide
440 g of Portuguese rosin and 1060 g of a cyclopentadiene resin (iodine
number 197 g of iodine/100 g of resin, melting point 75.degree. C.) are
melted, 650 g of nonylphenol, 4 g of sodium hydroxide and 440 g of
paraformaldehyde are added and the mixture is condensed for 4 hours at a
temperature of 130.degree. C. and a pressure of 1.5 bar. The pressure is
then set to atmospheric and the mixture is heated to 260.degree. C. while
distilling off volatile components. After 16 hours, the reaction is ended
by cooling the mixture. The yield is 2310 g (90% of theoretical), the
melting point is 155.degree. C., the viscosity of a 40% strength by weight
solution in mineral oil of boiling range from 240.degree. to 270.degree.
C. and aniline point of 72.degree. C. is 85 dPa.s. The resin solution is
only slightly turbid, thus contains hardly any undissolved material. To
determine the formaldehyde content, the distillate is admixed with aqueous
hydroxylamine hydrochloride solution, the liberated hydrochloric acid is
back-titrated with potassium hydroxide solution and the formaldehyde
content is thereby determined. The formaldehyde content is below 0.1%.
EXAMPLE 5
Preparation of a resin with condensation of aldehyde and phenol in solution
in the presence of lithium hydroxide
300 g of rosin and 300 g of xylene are heated to 260.degree. C. in a 3 l
pressure apparatus. 700 g of dicyclopentadiene containing 75% of
cyclopentadiene units are metered into this in the course of 2 h and the
mixture is maintained for a further 5 hours while stirring at this
temperature, the pressure which had initially risen to 9 bar dropping back
to 5 bar. The resin solution is then allowed to cool to 110.degree. C. 627
g of nonylphenol, 172 g of paraformaldehyde and 1.2 g of lithium hydroxide
are then added to this cooled solution. The apparatus is then closed and
made pressure-tight and is heated to 150.degree. C. for 4 hours, a
pressure of up to 4 bar being established. The vessel is then
depressurized to atmospheric pressure by flushing with nitrogen and is
heated to 260.degree. C. with xylene, water and other volatile components
distilling off. After 16 hours reaction time at 260.degree. C., 1550 g
(86% of theoretical) of a brittle solid resin having a melting point from
165.degree. C. are obtained. A 40% strength by weight solution in a
low-aromatic mineral oil of boiling range from 240.degree. to 270.degree.
C. and aniline point of 72.degree. C. has a viscosity of 80 dPa.s. The
solution is clear and shows no insoluble material. The compatibility of
the resin with mineral oil is better than 1:10.
EXAMPLE 6
Use example
From the product of Example 1 an ink A was prepared and from the product of
Comparative Example 1 an ink B was prepared, and the two were compared by
testing in use. The following recipe was employed:
A base varnish containing 35% by weight of the printing ink resin, 13% by
weight of a commercial alkyd resin (viscosity 200 dPa.s, oil length 76%),
19% by weight of linseed oil and 33% by weight of high-boiling mineral oil
of boiling range from 280.degree. to 310.degree. C. is prepared in each
case. A printing ink paste containing 32% by weight of pigment and 68% by
weight of varnish is prepared therefrom using Litholrubin L6B and
dispersion in a triple-roll mill. This is diluted with base varnish and
mineral oil, and manganese naphthenate as drier is added in a muller to
prepare a ready-to-print ink comprising 50% by weight of the paste, 41% by
weight of the base varnish, 7.5% by weight of mineral oil of boiling range
from 280.degree. to 310.degree. C. and 1% by weight of drier. This is
printed onto art paper APCO II/II on the test printing device from Prufbau
and the test prints are evaluated as a function of the amount of ink
transferred. The tack and the absorption of the inks are determined. The
results of the tests on these printing inks are shown in the table.
Definitions
Tack (measure of ink transfer); measured with the Inkomat from Prufbau
Absorption (measure of drying); the evaluation is carried out with the aid
of the test printing device, with lateral reversal onto unprinted paper
immediately after printing. The less color transferred in the lateral
reversal, the better the drying. Evaluation is carried out visually, with
the mark 1 being very good performance, the mark 6 being very poor
performance.
______________________________________
Ink A B
______________________________________
Viscosity of base varnish
30 8.5
[Pa .multidot. s/23.degree. C., shear rate 50 s.sup.-1 ]
Viscosity of printing ink
43 19
[Pa .multidot. s/23.degree. C., shear rate 50 s.sup.-1 ]
Tack of the printing ink at 200 m/s
10.3 21
Absorption [mark 1 to 6]
2.0 5.5
______________________________________
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