Note: Descriptions are shown in the official language in which they were submitted.
BACXGROUND OF THE INVENTION
.
Field of the Inven-tion - This invention rela-tes to
a process, a composition, a method ancl articles o manu-
facture containing the composition ~ore specifically, this
invention is directed to a process for the synthesis of a
smoke retardant composition, a method for supression of smoke
during the combus-tion of polymeric materials, and polymeric
materials containing such smoke retardant compositions. This
invention also provides a novel technique for the recovery of
finely divided particles o~ cupric oxalate and amine
molybdates.
Description of the Prior Art - The use o~ physical
mixtures of cupric oxalate and amine molybdates as smoke
supressants in vinyl hal:ide polymers has been previously dis-
closed by McRowe and Kroenke in U.S. Patent 4,053,453. Theindividual ingredients of their synergistic mixture are
separately synthesized and thereafter combined, either prior
to the addition of said mixture to the vinyl halide polymer,
or said ingredients can be combined within the vinyl halide
polymer.
The synthesis of cupric oxalate is fairly straight-
forward. This salt can be readily prepared by contacting
stoichiometric quantities of hot concentrated solutions of
cupric sulfate and oxalic acid. The resulting precipitate,
cupric oxalate, is recovered ~y filtration and thereafter
dried. The effluent which remains subsequent to such
synthesis contains sulfuric acid and can be disposed of by
. ~
conventional treatment techniques. Although the chemistry
involved in the preparation of the above material is fairly
uncomplicated, recovery of the cupric oxalate from the
reaction slurry is quite difficult due to the very fine
particle size of the reaction product. These problems have
been fully documented in the patent literature and techniques
have been devised for the synthesis of cupric oxalate so as
to produce a particulate product which can be readily re-
covered by conventional filtration procedures, U.S. Patent
3,846,460 (to Fite~. The Fite synthesis does, however, have
some serious drawbacks since the product which is prepared is
invariably contaminated with minor quantikies oE iron. The
presence of iron in vinyl halide polymers, even in very
minor quantiti~s, is unde~irable because of the relative
oxidative instability of this impurity and the influence such
material can have upon the color of the polymer. Thus,
cupric oxalate containing iron impurities is generally un-
satisfactory for use in vinyl halide polymers where these
polymers are to be used in the fabrication of articles which
are to be exposed to the degradative forces of oxidation
and/or require certain aesthetic and/or color charac-teristics.
The synthe~is of amine molybdates can be achieved
by reacting an amine with a molybdenum containing compound
such as molybdenum trioxide, molybdic acid, an ammonium or
alkali metal salt of molybdic acid or mixtures thereof in an
aqueous medium. It is essential to add acid to this aqueous
medium, either prior to contact of the above reactants or
-- 3
'' :;: ', ':
,. . -:
" ~, .. .
.
subsequent to their reac~ion in order to effect conversion
of the thermodynamically unstable complex which is formed
between such materials into a more stable (and commercially
acceptable) salt.
As is evident from the above discussion, the
requirements for the synthesis o cupric ox~late and amine
molybdates are quite specific, especially if such ingred-
ients are to be used in conjunction with vinyl halide
polymers. Unfortunately, neither o these ingredients can
be conveniently prepared, especially the cupric oxalate,
without introducing some contaminants (i.e., filtering aids)
into the desired compound. As noted herein, cupric oxalate,
and amine molybdates to a lesser degree, are generally pre-
pared as very fine particulates and, thus, are difficult to
recover from the reaction medium. Where modification of the
reaction scheme is attempted, as described in the previously
discussed patent to Fite, the ease of recovery is improved,
however, at the expense of the purity o~ the :recovered
product. Thus, there is a continuing need for an effective
method for synthesis of the above materials in a fashion
which f~cilitates their recovery and yet does not detract
from the purity of the recovered product.
SUMM?.RY OF THE INVENTION
Accordingly, it is the object of this invention to
remove the above as well as related deficiencies in the
prior art.
More specifically, it is the principal object of
this invention to provide a process for the synthesis o~
cupric oxalate which permits facile recovery thereof from a
reaction slurry.
Another object of this invention is to provide a
process for the synthesis of amine molybdates which permits
facile recovery thereof from a reaction slurry.
Yet another object of this invention is to provide
a process for the sequential synthesis of cupric oxalate and
amine molybdates in a common reaction slurry under conditions
which would permit facile recovery of both products from such
slurry without filtering aids.
Still yet another object of this invention is to
provide a composition suitable for reduction in the level of
air borne combustion products resulting Erom the pyroLysis of
polymers, especially vinyl halide polymers.
Additional objects of this invention include the
provision of polymers and articles prepared therefrom which
possess enhanced resistance to smoke generation during the
combustion thereof.
The above and related objects are achieved by pro-
viding a process for the synthesis of cupric oxala-te and
amine molybdates in a common reaction slurry. In this
process, an amine molybdate can be initially prepared by
contacting, in an appropriate medium (such as water) and at
elevated temperatures, molybdenum trioxide, molybdic acid,
an ammonium or alkali metal salt of molybdic acid or mixtures
thereof with an appropriate amine, followed thereater by
_ 5 _
the addition, to the same medium, of oxalic a~id and cupric
sulfate (preferably in equimolar amounts). The mole ratio
of amine to molybdate containing compound is preferably
about 1:1. The reactants are heated in this medium to a
temperature in the range of or about 50 to 100C. for a
period sufficient to effect substantia:L completion of the
synthesis of desired products. The solids which are formed
in the reaction medium can be easily recovered by filtration.
The recovered product is comprised of essentially unitary
particles containing both cupric oxalate and an amine molyb-
date in intimate physical association.
DESCRIPTION OF THE INVENTION
INCLUDING PREFERRED EMBODIMENTS
The process o~ this invention can be c:arried out
15 by addition to a common reaction medium oE the ingredient~
necessary to form amine molybdate, the ingredients necessary
to form cupric oxalate or by essentially simultaneous addi-
tion of the ingredients to form both the amine molybdate and
the cupric oxalate. The sequence of addition of the various
reactants to the medium can, however, effect the yield and
the physical characteristics of the solids which are pro-
duced as a result o~ their reaction with one another.
The amine molybdates prepared according to this
process are produced by reacting an organic amine with a
molybdenum containing compound, such as molybdenum trioxide,
molybdic acid or an ammonium or alkali metal salt of molybdic
acid. The amine molybdate normally con-tains from about 1 to
: . ~. , ' "
..
2 moles of molybdenum per mole of amine. The synthesis of
such molybdates are fully described in U.S. Patents 4,053,453
and 4,053,455. As noted previously, it is preferable that
amine molybdate formation occur in an acidic medium so as to
insure the formation of a thermodynamically stable product.
Amines which are suitable for use in the preparation of amine
molybdates can contain from about 1 to 40 carbon atoms and
from about 1 -to 10 primary, secondary and tertiary amine
groups or any combination thereof. In the most preferred
embodiments of this invention, the organoamine molybdates
will contain from about 1 to about 20 carbon atoms and 1 to
4 primary amines or heterocyclic secondary amine groups.
Examples of amines which are suitable for use in the
synthesis of thesç compounds include the aliphatic, the
alicyclic, the aromatic and heterocyclic amines. The
aliphatic amines which are especiaIly preferred for use in
this synthesis include ethylamine, ethylenediamine, 1,2-
propanediamine, 1,3~propanediamine, 1,4-butanediamine, 2-
methyl-1,2-propanediamine, 1,5-pentanediamine, 1,6-hexane-
diamine, l,7-heptanediamine, 1,8-octanediamine, 1110-decane-
diamine, l,12-dodecanediamine, and the like. Aliphatic
polyamines which are suitable in preparation of the above
compounds include d;ethylenetriamine, diethy]enetetramine,
tetraethylenepentamine, bis(hexamethylene)triamine, 3,3'-
iminobispropylamine, guanadine carbonate, and the like. The
preferred alicyclic diamines and polyamines which can be
used in the synthesis of the above compound include 1,2-
diaminocyclohexane, 2',4-diamino-1-propyl-4-methylcyclo-
hexane, and the like. Aromatic amines such as aniline and
naphthalamine are also suitable for use in the preparation of
the above compounds. Heterocyclic amines such as melamine,
N,N-dimethylanaline, pyridine, piperazine, hexamethylene-
tetraamine, 2,2,4-trimethyldecahydroquinoline, 2,4,6-tri-
(morpholino)1,3,5-triazine and N-(aminoalkyl)-piperazineS
wherein each alkyl group contains from about 1 to 12 carbon
atoms and preferably from 1 to 6 carbon atoms can also be
employed in this process. Polymeric amines are also suitable
for use in preparation of the above compounds and such
suitable substances include polyethyleneimine, polyvinyl-
pyridine, polyvinylpyrolidine, and poly~2,2,4-trimethyl-1,2-
dihydroquinolyl).
Excellent results in preparation of the above com-
pounds have been obtained wherein the amine is melamine,
piperazine and alkyl amines wherein the alkyl substituent
contains 1 to 8 carbon atoms.
Substituted melamines which are suitable in prepar-
ation of the above compounds can be represented by the
following ~ormula:
-- 8 --
.. :,. :
;~ ,
,- '
~x\ /x~
'` X/ N ~ O ~ N \X~'~
N
X~ \X
wherein X is hydrogen or an alkyl, alicyclic,
aralkyl, alka'ryl, aryl or heterocyclic group containing from
- 1 to 10 atoms of C, O, S and/or N. Any -two of the substit-
uents on each of two or more pendant nitrogen atoms may also
be joined together to form a heterocyclic ring such as a mor-
pholino group in 2,4,6-tri(morpholine)-1,3,5-triazine. Other
examples of suitable substituted melamines include N,N',N " -
hexaethylmelamine; 2-anilino-~-(2l,4'-dimethylanilino)-6-
piperidino-1,3,5~triazin~; and 2,~,6-tr:i(N-methylarlilino)-
1,3,5-triazine.
Cupric oxalate can be prepared by reacting stoich-
iome~ric amounts of hot concentrated solution of cupric
sulfate and oxalic acid. The formation of this product in
the common reaction slurry can precede or follow the addition
of other reactants thereto.
The reaction medium which can be used in this
synthesis is preferably a solvent for the various reactants
contemplated for addition thereto and essentially a non-
solvent for the product o-E this synthesis. Any highly polar
fluid, such as water, lower alkyl alcohols or mixtures
thereof would appear to be suitable for use as the reaction
medium in this process. The amount of reaction medium
' ~
.. ..
'' ' ~' ~ ~ ;,
-
relative to reactants should be adequate to effectively dis-
solve such reactants and not present in such excess as to
inhibit interaction thereof.
As noted previously, the sequence of addition of
the reactants to the reaction medium can affect both the
yield and the physical characteristics of the solvents thus
produced. In a preferred embodiment of this invention the
ingredients necessary for the formation of the amine molyb-
date are initially added to the reaction medium and the
cupric oxalate formed within the medium ~hereafter. The
formation of acid during the subsequent synthes~s of cupric
oxalate serves to stabilize the amine molybdate. The
sequential synthesis of these materi~ls in a common reaction
medium in the manner set orth hereinabove results in the
formation of a unique partlculate product which contains
both amiNe molybdate and cupric oxalate in intimate associ-
ation. This particulate product can be readily separated
from the reaction medium by conventional filtration tech-
niques. Because both components of this composition are con-
tained in a single physical entity, subsequent additionthereof to polymeric resins is greatly simplified.
The reaction conditions prevailing during such com-
bined synthesis are essentially the same were such materials
to be prepared in separate vessels. The parameters for
synthesis of amine molybdates are set forth in V.S. Patents
4,053,453 and 4,053,455. Typically, such a synthesis simply
-- 10 --
,. .
''';
., ,
involves dissolving an organic amine and a molybdenum con-
taining compound in separate containexs, heating each
solution to a temperature in the range of from about 50 to
100C. and combining the solutions under controlled
conditions over a relatively brief period of time with
agitation. Ordinarily, were such amine molybdates to be pre-
pared separately, dilute acid must also be intr~duced into
the reaction medium in order to effect stabilization of the
amine molybdate compounds which are ormed therein. However,
in the combined synthesis of this invention such acid
addition is not required since the reaction of oxalic acid
and cupric sulfate in this reaction medium will ~enerate
sufficient acid to effect the stabilization of the amine
molybdate compound. In a similar fashion, separate solutions
of oxalic acid and cupric sulfate (generally a hydrated Eorm
of cupric sulfate) are prepared and added to the reaction
medium in sequence following the addition thereto of the
organic amine compound and the molybdenum containing com-
pound. The solution containing the cupric sulfate is,
however, carefully metered into the reaction medium by drop-
wise addition over a relatively brief period of time. The
entire reaction medium is agitated during such addition and
the temperature thereof generally increased until refluxing
thereof is achieved. The system is heated for an additional
two hours from this point, allowed to cool and the resultant
product separated from the reaction slurry by filtration.
The recovered product can thereafter be washed with water or
-- 11 --
..
other suitable solvent and dried under vacuum. The solid
materials recovered from the reaction slurry comprise
essentially unitary particles of amine molybdate and cupric
sulfate in intimate association. The solids recovered from
the reaction medi~m in this fashion are generally of a
particle size suitable for use in polymer compositions. The
particle size o~ the recovered solids prepared according to
the process of this invention can range from about 0.01 to
about 800 microns, and preferably from about 0.5 to about
200 microns. In the event that the particle size of solids
recovered from the reaction medium is in excess of that
stated hereinabove, or in excess of the preferred dimension,
such solid can be subjected to the attritive forces o a ball-
mill or other equivalent deviae for a period suficient to
reduce its size to the desired level.
The polymers of the compositions of this invention
can include vinyl halide homopolymers, copolymers, blends
and~or mixtures of homopolymers and/or copolymers. The vinyl
halides which are preferred in such compositions include
vinyl chloride and vinylidene chloride polymers that contain
up to about 50~ by weight of at least one other olefinically
unsaturated monomer, more preferably at le~st one other
vinylidene monomer (i.e., a monomer containing at least one
terminal CH2=C~ group per molecule) copolymerized therewith,
even more preferably up to about 20% by weight of such
monomers. Monomers which are suitable in preparation of
such polymer compositions include ~-olefins containing from
- 12 -
2 to 12 carbon atoms, more preferably from 2 to 8 carbon
atoms, such as ethylene, propylene, l-butene, isobutylene,
l-hexene, 4-methyl-1-pentene, and the like; dienes contain-
ing from 4 to 10 carbon atoms including conjugated dienes as
butadiene, isoprene, piperylene, and the like; ethylidene
norbornene and dicyclopentadiene; vinyl esters and allyl
esters such as vinyl acetate, vinyl chloroacetate, vinyl
propionate, vinyl butyrate, vinyl laurate, vinyl benzoate,
allyl acetate, and the like; vinyl aromatics such as styrene,
a-methyl styrene, chlorostyrene, vinyl toluene, vinyl
naphthalene, and the likei vinyl and allyl ethers and ketones
such as vinyl methyl ether, allyl methyl ether, vinyl iso-
butyl ether, vinyl n-butyl ether, vinyl chloroethyl ether,
methyl vinyl ketone, and the like; vinyl nitrile~ such as
acrylonitrile, methacrylon:Ltxile, and the like; cyanoalkyl
acrylates such as ~-cyanomethyl acrylate, the a-, ~- and y-
cyanopropyl acrylates, and the like; olefinically unsaturated
carboxylic acids and esters thereof, including ~
olefinically unsaturated acids and esters thereof such as
acrylic acid, methacrylic acid, ethacrylic acid, methyl
acrylate, ethyl acrylate, chloropxopyl acrylate, butyl
acrylate, hexyl acrylate, 2-ethylhexyl acrylate, dodecyl
acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl
acrylate, glycidyl acrylate, methoxyethyl acrylate, ethoxy-
ethyl acrylate, hexylthioethyl acrylate, m~thylmethacrylate,ethyl methacrylate, butyl methacrylate, glycidyl meth-
acrylate, and the like~ wherein the alkyl groups contain 1
- 13 -
. _
': . ~ , . ;,
:,
,
~q~
to 12 carbon atoms, and including esters o~ maleic and
fumaric acid, and the like; amides of the ~,e-olefinically
unsaturated carboxylic acids such as acrylamide, meth-
acrylamide, and the like; divinyls, diacrylates and other
poly~unctional monomers such as divinyl benzene, divinyl
ether, diethylene glycol diacrylate, ethylene glycol dimeth-
acrylate, methylenebis-acrylamide, allyl pentaerythritol,
and the like; and bis(~-haloalkyl) alkenyl phosphonates such
as bis(~-chloroethyl) vinyl phosphonate, and the likeD
A group of particularly useful comonomers include
l-olefins containing from 2 to 8 carbon atoms; vinyl esters
and allyl esters; olefinically unsatuxated carboxylic acids
and.esters thereof, especially a,B-olefinicall~ unsaturated
acids and esters thereo~; esters o:E male.ic and :Eumaric acid,
and the like; amide5 o~ u,~-ole~inically unsaturated carbox-
ylic acids; and vinylidene or vinyl chloride.
Also included are chlorinated vinyl chloride and
blends of vinyl and vinylidene chloride polymers and co-
polymers with other polymers, both plastics and elastomers,
for example, with an ABS resin containing 10 to 40% of copolymers
of styrene and acrylonitrile or styrene and methyl meth-
acrylate wherein styrene i.s the major component, elastomers
containing about equal amounts of styrene and acrylonitrile
with butadiene, polyurethanss, nitrile elast~mers, both
liquid and solid containing from about 15 to 40% acrylo-
nitrile with the remainder butadiene, polyolefins, and the
like. These vinyl chloride polymers normally are high
14 -
.
" , ' ' '` " ' ~,
molecular weight polymers having a specific viscosity greaterthan 0.4 measured as a 0.4% solution in nitrobenzene.
The vinyl chloride and vinylidene chloride polymers
may be prepared by any method known to the art such as by
emulsion suspension, bulk or solution polymerization. The
smoke suppressant composition prepared according to the
process of this invention may be mixed with the polymer
emulsion, suspension, solution or bulk mass before monomer
xecovery and/or drying. More preferably, the smoke suppres-
sant may be mixed with dry granular or powdered polymers.The above mixture may be blended thoroughly in granular or
powder form in apparatus such as aHensche~mixer,or ~equivalent
device. Alternatively, this step may be eliminated and the
mixing done while the polymer mass is fluxed, fused and
masticated to homogeneity under fairly intensive shear in or
on a mixer apparatus having its metal surface in contact
with the material. The fusion temperature and time will
vary according to the polymer compositions and level of
smoke suppressant and will generally be in the range o~
about 300 to 400F. for 2 to 10 minutes.
The vinyl chloride polymers can also be pre-mixed
with standard compounding ingredients known to those skilled
in the art,(e.g., plasticizers, lubricants, stabilizers,
fillers, colorants, processing aids, other flame and smoke
retardants, and the like). While the smoke suppressants of
this invention are most effective in vinyl chloride polymers
substantially free of plasticizers, they are also of value
- 15 -
* trademark
,'' ~.~
;' :,., .~
:. .
,... . . . .
in reducing smoke formation during combustion of plasticized
vinyl chloride polymers.
Smoke retardation may be measured using an NBS
Smoke Chamber according to procedures described by Gross
et al, "Method for Measuring Smoke -from Burning Materials",
Symposium on Fire Test ~ethods - Restraint ~ Smoke, 1966,
ASTM STP 422, pp. 166-~04. Maximum smoke density (Dm) is a
dimension~ess number and has the advantage of representing a
smoke density independent Oe cham~er volume, specimen size
or photometer path length, provided a consistent dimensional
system is used. ~Iaximum rate of smoke generation (Rm) is
defined in units of min. -1. Percent smoke reduction is
calculated using this equation:
Dm/y of sample - Dm/g oE control
~c 100 .
Dm/g of control
The term "Dm/g" represents maximumsmoke densi~y per gram of
sample. Dm and other aspects of the physical optics of
light transmission through smoke are discussed fully in the
above ASTM publication.
The Examples which follow further define, describe
and illustrate the improved process Oe this invention.
Apparatus and techniques used in this process and in the
evaluation of the products prepared by this process are
standard or as hereinbefore described. Parts and percentages
appearing in such ~xamples are by weight unless otherwise
indicated.
EXAMPLE I
To a one liter reactor fitted with a stirrer,
heater, and reflux candenser was charged 300 grams of water
and 15.~4 grams (0.1193 moles) melamine. The slurry was
stirred and heated to 100C. In three separate beakers the
following ingredients were dissolved with heating and
stirring:
W'eight Amount
in of Water Temp.
Compound Grams Moles in Grams (C.)
Ammonium 40.56 0.1193 50 85
dimolybdate
Oxalic Acid43.64 0.3462 118 90
Cupric Sulfata, 81.82 0.3277 100 95
pentahydrate
The hot ammonium dlTnolybdate solution was con-
veniently added to the melamine reaction flask over a period
of 15 minutes with stirring at 150 rpm. The slurry was
allowed to cool at 85C. and thereafter the oxalic acid
solution (also at 85C.) was added in a similar fashion over
a 15 minute period. The cupric sulfate solution was metered
into the reaction slurry by dropwise addition from an
electrically heated addition funnel. The duration required
for the addition of such material was 20 mimltes. The entire
reaction mix-ture was stirred and heated to 100C. under
reflux conditions for an additional two hours. The slurry
was then allowed to cool, the solids separated from the
reaction medium by filtration and washed with cold water.
The solids were dried in a vacuum oven. The yield was
approximately 97~ of -the lO~ grams theoretical yield.
EXAMPLE II
The procedures o .F.xamp:Le ~ we~e repeatec~ excep~
for -the substitution of one of the Eol.Iowing amin~ mo~ybdate~
~o.r melam.i~e molybdates:
(a) Ethylene mol~bdat:~
(b) Pyrid.ine molybdate
(c) P.iDerazine molybd~te
(cl) Hexame-thylene tetram:i.n~ moly~at~?
(e) Guanad.ine mo:Lybdate
(f) AnJ.line molybdat~
(g) ~,N~dimethylan.ilille moly~d<~ke
(h) N,M',N''-hexa~l:hy.l.n~e~.c~ ;n~ ~no:Ly)~c1cl~.c~
(i.) 2-~lnll:i.no~2',4'~-c1:i.1n~ n:i~Ln.o)~
piperadi.no :1.,3,5-1:riazi.r1~ mo:Lybd~c-~
(j) 2,4,6~tri(N-meth~:L ani~ino)~l t 3~S--
triazi.ne mo:L~bcla~e
(k) 2,4,6-tri(morphol;lno)-l,3,5 tx:iaz.inc?
molybclate
(l) 2,2,4-trlm~thy:l.decah~dro~u.i.nol.ine
mol~bdate .
EX~~L
The smoke supprcss~nt p~epar.ed in the m~r1n~r cle~-
~cribecl in Example I is combin~d w.ith po:lyvinylc~h:lori.c~e ~esin
(the resin having a specifi.c ~fiSCC>Sity ~f 0. 3~0~f~ in
nitrobenzene at 30C,) by dry m~ ing these inc1redierli:s ir
a relative welght ratio of ahoul: 2.~ parts b~ weic1ht: s]~ok~
l8
. ..
; ' ' ' ~
, ~ , . .
a~ hA~
suppressant per 100 parts by weight polymer. In addition to
the above constituents, the following standard ingredients
are also added to the mixture in the following concentrations:
2 parts by weight of dibutyltin bisiso-
octothioglycolate (antioxidant)
4 parts by weight processing aid
3 parts by weight titanium d:ioxide
1 part by weight calcium stearate
1 par-t by weight methylene bis stearamide
+The concentration of the above ingredients is given
per 100 parts by weight polymer.
Subsequent to admixture of the above ingredients,
the resultant powder is placed upon a heated 10 inch 2-roll
mill and formed into sheets. The resultant sheets are cut
into samples of predetermined sizes. A sample approximately
6" square is placed in a sheet mold and pressed at 320F.
for three minutes until its thickness is redued to about
25 mils. A 3x3 inch sample of this sheet is t:hereafter
tested in an NBS smoke chamber operated in the flaming mode.
Test results from this evaluation compare very avorably
with samples of materiais devoid of smoke suppressant. On
the average, smoke suppression is reduced by at least 50 and
in some instances up to 75~. Samples which have been
subjected to the above evaluation also exhibit enhanced
stability over tin-sulfur stabilized compositions with
respect to the color characteristics of the material.
19
.~. ' .
.
EXAMPLE IV
The procedure of Example III is repeated with the
smoke suppressant compositions of Example IIa-l. In each
and every instance, the comparative results obtained are
substantially equivalent to those reported for Example III.
The foregoing examples have been providea to
illustrate some of the preferred embodiments of this inven-
tion and not intended to delineate its scope, which is set
forth in the claims which follow.
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