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Патент USA US2402872

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aEsme 25, 1946.
Filed NOV. 23,' 1943
n2. z.
20 30
40 d'0 60 70
Frank ÍV'LClar‘k ,
y His Attorney.
Patented June 25, 1946
2,402,872 .
Clark, Pittsfield, Mass., assignor to Gen
' eral Electric Company, a corporation of New
Application November 23, 1943, Serial No. 511,440
8 Claims.
.( o1. 252-66)
The present application relates to chlorinated
stability and otherwise is Well suited for practical
nitronaphthalene compositions and is a con
use. Trichlor alpha nitro naphthalene, in partic- .
tinuation-impart of my earlier application Se
rial No. 466,021, ñled November 18, 1942„ which in
ular, has been found to possess the best combina
tion of properties whereby desirable characteris
tics are imparted to capacitors and other electric
turn is a continuation -oi' application Serial No.
355.588, ñled _September 6, 1940.
devices, as, high efficiency, long life and desirable
temperature-capacity characteristics.
-It comprises new compositions suitable for di
electric and insulating purposes in electric ca
pacitors, capacitance bushings, or other electric
In preferred compositions embodying my inven
‘ tion trichlor alpha nitronaphthalene constitutes
devices, and in particular compositions consisting 10 at least about l0 per cent and up to about 40 per
cent of the entire composition. However, for
wholly or in part of trichlor alpha nitronaphtha
Iene. My invention also includes compositions in
which chlorinated nitronaphthalene is associated
with halogenated polyphenyl products as, for ex
some purposes the content of such chlorinated `
alpha nitronaphthalene may be as high as 60 per
` cent and in other cases may be as low as a fraction
ample, pentachlor diphenyl.
of one per cent.
In the accompanying drawing Fig. 1 is a
paper-spaced capacitor# shown partly unrolled,
blends comprising about 80 to_90 per cent of chlo
rinated diphenyl and about 20 to 10 per cent of
as an example ci a device for the impregnation
of which compositions embodying the present in
trichlor alpha nitronaphthalene have the unique
property of operating with substantially constant
capacity -over the range of temperatures at which
capacitors ordinarily operate, that is, from 25 to
100° C. or thereabouts, these limits being only
vention are suitable; Fig. 2 is a graph showing
the relation of capacity to a range of compositions
containing trichlor alpha nitronaphthalene; Fig.
3 is a graph .showing the dielectric constants for
a range of compositions made up of pentachlor
diphenyl and trichlor alpha nitronaphthalene;
Fig. 4 is a graph showing the relation of capacity
to temperature for a range of compositions em
_ Compositions consisting mainly of mixtures of _
Alpha nitronaphthalene may be chlorinated by
methods usually employed for the chlorination of
aromatic compounds.
Preferably a suitable cat-v
bodying my invention; and Fig. 5 is a graph show
alysvt should be present, for example, iron, an
v ing the relation to capacity to temperature for a
timony, iodine or aluminum. Chlorination is con
speciûc composition made-_ in accordance with my 30 tinued until the amount of combined chlorine as
determined by the speciñc gravity or the weight
Capacitors ordinarily contain sheet material
of a sample of the product has reached a value
spacers or septa between metal armatures, as for
.corresponding to a desired chlorination product.
example capacitor linen or kraft paper. Capac
For example, trichlor alpha nitronaphthalene
itor spacers also may consist of derivatives of ce1 35 may be prepared by the following procedure:
lulose, such as sheets or tapes of cellulose acetate,
To 1780 parts byweight of alpha nitronaph
Cellophane or cellulose ethers, as for.. example
thalene is added a suitable catalyst, such for ex
ethyl cellulose and its modifications. When
ample as about 5 parts of comminuted iron. The
coated or impregnated with my new compositions,
mixture is heated to produce fusion which takes
such spacers show surprisingly good dielectric 40 place at a temperature of about 60 to 70° C. chlo
rine gas is bubbled through the fused mass. The
Chlorinated nitronaphthalenes like all nitro
temperature should be raised as chlorination
compounds, are not characterized by a high de
proceeds. The following schedule’ is a general
gree of chemical stability. When subjectedV to
heat in the range of from 75 to 100 C. or to light,
When the increase in weight of the product
even at room temperature, these compounds'de-A
indicates that the chlorination has progressed to
teriorate chemically. Theydarken yin color and
about one to two atoms per molecule (abouty 22
increase in acidity and otherwise show a chem
per cent chlorine), the chlorination is somewhat
ical change which normally would be expected
slowed. In order to accelerate the reaction the
to result in a high degree of electrical instability 50 temperatureis raised to about 70 to 90° C. When
in any dielectric assembly of _which they might be
the total combined chlorine corresponds to about
a part. Surprisingly, the contrary has been found
2.5 atoms per molecule (about 34 per cent chlo
to be true. Electrical apparatus when impreg
-rine), the reaction temperature should be raised
nated with my improved dielectric compositions
to about v9_0 to 110° C. It is maintained in this
is characterized by a high degree of electrical
range untilthe increase in weight indicates about
38 per cent chlorine in combination. This is the,
theoretical amount of chlorine present in trichlor
alpha nitronaphthalene.
The chlorination then is discontinued.
reaction mass is cooled and dissolved in a suitable
solvent as, for example, carbon tetrachloride.
The iron particles are removed by ñltration. The
solution is washed with an alkali, for example, a
one per cent aqueous solution oi' sodium car
bonato. The neutralized solution is concentrated
by evaporation until crystals of trichlor alpha`
nitronaphthalene separate therefrom. These
crystals are removed by filtration, or other con»
venient way, and dried in air or under vacuum
or other known method. The crystalline product
traces of the hydroxide. Purification by distil
lation may be practised. Some decomposition
may occur of the product being distilled. In that
case. the distillate should be purined and neu
tralized by washing with 3 to 5 per cent solution
of sodium hydroxide and dried by heating under .
reduced pressure.
Trichlor alpha- nîtronaphthalene can be assc~
elated advantageously with chlorinated diphenyl
or equivalent hologenated polyphenyl compound.
- By the term “polyphenyl compound"> I mean to
include various equivalents of dìphenyl, for eig,
ample, diphenyi oxide, diphenyl methane, dì~
phenyl ketone, diphenyl benzene, and the like.
While chlorine ordinarily is employed as the
preferred halogen, other halogens, notably fluo
at this stage has a melting point of about 132 to
135° C. It is-.suitable without further purifica
rine, may be employed within the scope of my
tion for many electrical uses. For some purposes
A capacitor treated with a composition con
a more highly purified product may be desirable.
taining» 75 parts of pentachlor diphenyl and 25
This can be obtained by recrystallization. The
parts of trichlor alpha nitronaphthalene oper
melting point of the pure product is about 155° C.
ates with a 7.5 per cent higher capacity at 100°
Alternatively, the chlorination may proceed in
' than a. similar capacitor treated with. pentachlor
the presence ofv an iron catalyzer until approxi
diphenyl imassociated with a modifying ingre
mately 38 per cent of chlorine has been intro
' dient.
duced. At this stage most of the product will con
Compositions containing up to about 60 per
sist of trichlor alpha nitronaphthalene. Some
cent of said trichlor nitro-naphthalenc product.
tctrachlor and some dichlor alpha nitronaphn
the remainder consisting of pentachlor diphenyl,
thalene may be Present inthe chlorination prod.
not only result in a markedly higher capacity
uct. The mixture may be purified by distillation.
It has a boiling point in the range of 230 to 280° C. 30 when used as impregnants for paper-spaced ca«
pacitors than does such pentachlor diphenyl un~
at a pressure of 15 millimeters of mercury. The
associated with the naphthalene compound, but
yield'obtained is about 80 to 90 per cent. l':’re«r
other advantages accrue. Capacitors when im
sumably because of the presence of small amounts
pregnated with approximately 90 parts pentachlor
diphenyi associated with approximately l0 parts
of dichlor andv tetrachlor products, the distillate
cools to a non-crystalline, resinous solid at room
of trichlor anitronaphthalene are characterizedA
by a constant electrical capacity over a tempera
ture rango from about 25 to 100“ C. Compositions
consisting by weight of '75 to 90 parts of Denta
Viscosity at 98.9° C---„_`-_-- 50 to 55 seconds 40 clilor diphenyl and 25 to 10 parts of trichlor alpha
~ Saybolt Universal
nitrouaphthalene are liquid at room temperature,
Bpeclilo gravity at 100° C._„_ 1.555 to i565
which is advantageous in the dielectric field. The
most desirable proportion of the chlorinated
The distillation product may be refined by coni
tact with a .suitable absorbent, such as fullcr‘s , nitro-naphthalene in a dielectric composition de
temperature having the following characteristics. .
Color ................... -_ light yellow
Flow point ._a'. ___________ ..„ ’l0 to 15° C.
earth. preferably at 100° C. The product after
nltration has the following average properties.
ü ponds on the type of capacitor tissue, clampinr,1
pressure, etc., employed in the capacitor. In the
results to bc given, the impregnated capacitors
consisted of aluminum armatures separated by
Color ...... __'___________ _u light yellow
_Flow point ..-_-_ ..... __., ____ -„ '10 to 75° C.
spacers of kraft capacitor paper. The latter has
a thickness of .0004 inch. This thickness is not
critical but has been chosen as representing a
prevalent commercial thickness. Such a capaci
tor is shown in Fig. 1, armatures being repre
sented by the strips 2, 3. Two groups fl, 5 of
paper spacers. are illustrated. The enclosing case
is lnot shown. Electrical connection is made to
the armatures by the tap straps E, l. The im~
proved characteristics are indicated by graphs
Viscosity ________________ -_ 54 seconds Baybolt
Universal at
08.0° C.
Bpecißc gravity (100° C.)__- 1.2562`
Reaction (neutralization
number) ..---, ......... _.. 0 (neutral)
Condition at 25° C ________ __ n o n -- crystalline,
resinous solid
Dielectric constant at 25° C-- 8.0
Power factor at 80 cycles
25° C __________________ __ .i3 per cent
Hesistivity at 25° C _______ _- 20x10x2 ohms/cm.
resent a range of percentages, of the trichlor
Because of its non-crystalline condition, this
composition is well adapted for the impregna
tion of high voltage capacitors even without the
l addition of modifying ingredients.
l For the purification of some chlorinated prod
which will be presently explained.
In the graph shown in Fig. 2, the abscissa rep
naphthalene compound, aNOnCiuHiCla, in admix
ture of said compound with pentachlor diphcnyl
and the ordinates indicate in per cent a relative
65 increase or decrease of capacity as compared with
uots. a solution process is preferable. The -chlo
rinated product is dissolved in a suitable solvent,
a similar capacitor impregnated only with penta
clllor dlphenyl. The graph l here shown repre
" sents results taken at 100° C. capacitor tempera-
ture. Itwill be observed that although an in
auch,” carbon tetrachloride or trichlorbenzene.
The solution is ?ltered free from the` suspended 70 crease of capacity occurs when even small addi
catalyst if the catalyst is insoluble in the solvent
which is employed. The solution is washed with
water and, if somewhat acid, is washed with
dilute sodium hydroxide (3 to 5 per cent solu
tim) and is again washed with water to remove 75
tions of the naphthalene compound are present.
the capacity rises to a. maximum when the per«
centage of the naphthalene compound is between
about 30 to 40 per cent.
As shown in Fig. 3, the dielectric constant of
thc compositions of pentachlor diphenyl and tri
6 .
l ever, from ‘é to> 5 per cent of the chlorinated
chlor- anitronaphthalene reaches a. maximum at
about 15 per cent of the latter ingredient and
begins to decrease when the proportion of the
nitronaphthalene exceeds about 25 per cent. The
graph 9, which‘represents the dielectric' constant,
rises at 25° C. to approximately 6„75 and at 100° ' ' '
C. rises to approximately 5.8 before decreasing.
alpha nitro-naphthalene is present, this foil cor
rosion is substantially eliminated with resulting
dielectric stabilization of the capacity and a com
mercially satisfactory lengthof life.
ACapacitors impregnated with a composition in
cluding about 99 parts of pentachlor diphenyl
and 1 part of /trichlor alpha nitro naphthalene
are characterized by a power factor at 25° C. in
tions embodying my-iñvention are to be used 10 the range of„:30 to .35 per cent, and a direct cur
When capacitors impregnated with `composi
rent resistance value at least as high as 6000
under such. conditions/or-'in such circuits that the
varìation’äif'capacit/y would produce an unde~-
there is no 'change in capacity over a range >of
advantageous electrical~characteristics. Capaci
tors impregnated with either impregnant vfunc
Capacitors impregnated
sirable e‘i'î'ect, then the naphthalene compound . with a dielectric composition -consisting of 95
parts of pentachlor diphenyl and 5 parts of tri
should be _restricted to a range of about 10 to 20
chlor alpha nitronaphthalene similarly possess
per cent. As shown in the graph Il of Fig. 4,
temperature from about 25 to 100° C. when the>
percentage of aC1cH4ClaN0z in the mixture is
about 10 per cent. The graph Il crosses the zero
line when 10 per cent of the latter nitrochlor 20
compound is present in the mixture.
While I have illustrated my invention with 'par
ticular reference to compositions of chlorinated
tion satisfactorily on direct current voltage" un
der stresses as high as 1000 volts per mil without
dangerous loss in resistance or-'i increase in power
What I claim as new and desire to secure’byLetters Patent of the United States is:
1. A non-crystalline, light yellow, resinous
alpha nitro-naphthalene and pentachlor di
phenyl, it is not restricted _to such examples. 25 material composed essentially of trichlor alpha
nitronaphthalene, said material having a flow
Other chlorinated polyphenyl compounds can be
point of about 70 to '75° C., a dielectric constant
similarly associated with the chlor alpha. nitro
-of about 8, a power factor at‘ 60 cycles, 25° C. oi.'
naph-thalene. For example, dielectric blends of
about .13 per cent and a resistivity at said tem
trichlorl alpha nitronaphthalene and tetrachlor
diphenyl have advantageous dielectric properties. 30 perature of 29X 1012 ohms per centimeter cube.
2. A composition of matter consisting essen
Fig. 5 of the drawing, the graph l2, illustrates the
tially of chlorinated diphenyl and trichlor alpha
very slight changes in capacity of a capacitor
nitronaphthalene, the latter ingredient being
containing such blend over the temperature range
present in the range of about 10 to 40 per cent.
25 to 100° C. When impregnated with a dielec
3. A dielectric material consisting by weight of
tric composition made up oi' about 15 per cent 35
about 75 to 90 per cent of pentachlor diphenyl
of trichlor alpha nitronaphthalene and 85 per
and about 25 to 10 per cent of trichlor alpha
cent tetrachlor diphenyl, a substantially constant
, nitronaphthalene.
capacity results over this range. For many ap
4. A dielectric material which is suitable for
plications, especially in radio circuits, such con
capacltor'impregnation consisting by weight of
stan-t capacity feature is of particular value.
about one to 60 per cent by weight of trichlor
The most advantageous compositions will vary
alpha nitronaphthalene and about 99. to 40 per
in the ratio oi components depending on the par
cent of pentachlor diphenyl.
ticular components chosen. For example, to se
5. A liquid dielectric material which is suitable
cure constancy of capacity in a composition con
taining pentachlor diphenyl, 10 per cent of the 45 for capacitor impregnation consisting by weight
of‘about 90 to '75 parts of pentachlor diphenyl
nitrochlor compound is required, whereas` in a
and about 10 to 25 parts oi’ trichlor alpha nitro
composition comprising tetrachlor diphenyl> 15
per cent of the nitrochlor compound is required.
~ I also have found very small amounts of the
6. A liquid dielectric material whichìis suitable
-chlorinated alpha nitronaphthalene when asso 50 for capacitor impregnation consisting by weight
‘of 85 parts of pentachlordiphenyl and 15 parts
ciated with other dielectric material to be useful
of trichlor alpha nitronaphthalene. ,as a stabilizer, particularly for high temperature
'1. A liquid dielectric material which is suitable
-operation. When capacitors impregnated with
for capacitor impregnation consisting mainly oi'
chlor diphenyl, chlor diphenyl oxide or chlori
nated diphenyl methane are placed on direct cur 55 a chlorinated polyphenyl compound which is ad
mixed with at least about one-half of one per
rent voltage at a stress in the range of 500 to
cent of trichlor alpha nitronaphthalene.
1000 volts per mil (which is used in many com
8. A non-crystalline, resinous material having
inercia). applications), the capacitor is charac
a ilcw point-of about 70 to '15° C. composed es
terized by an unsatisfactory short life at tem
peratures of the order of 90° C. and higher. For 60 sentially of trichlor alpha nitronaphthalene and
containing as impurities amounts o! dichlor and
practical purposes, as for example in the case
tetrachlor alpha nitronaphthalene which are in
of many illter ~or blocking capacitors, operating
suflicient to cause the boiling point of the com
temperatures in the range of 90° C. and higher
position to depart from a normal range of about
even to 110° C., are encountered. The failure
of ordinary chlorinated polyphenyl capacitors in 65 230 to 280° C. at a pressure lci' 15 mm. of mercury.
this temperature range is accompanied by the
, etching and corrosion of the toil. When. how
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