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Patented Jan. 20, 1948
UNITED smug-mew0mm f
- POLYETHYLENE STABILIZED WITH BIS
(HYDROXYPHENYL) PROPANES
'
Georgev H. Latham, and Daniel E. Strain, Wil
mington, -Del., assignors to
du Pont de
Nemourssdr'company, Wilmington, Del._, a cor
poration ofDelaware
'
"
'
'
'
\
No Drawing. ApplioationFebruary3,1944, ;
_
' Serial No. 520,954
-
5 Claims. ‘(01. 260-94)
This invention relates to new compositions of
matter and particularly to new compositions of
matter comprising normally solid polymers from
.
2
,
»
oughly distribute .itv throughout the polymer...v
\ This-‘can .be accomplished in any machine suit,-, \
able for mixing solids, as by millingthe ethylene
ethylene. This application is in part a continua
polymer on heated rolls,‘such as are used-inthe' .
tion of our copending application S. N. 474,850 5 compounding of rubber, or other suitableymillin'g .
filed February 5, 1943.
'
equipment, and adding agent theretal Instead
In the practice of this invention any normally
of adding the agent to the polymer in the'solid or‘
solid polymer of ethylene made either by the
molten state it can be addedto a solution or
processes of U. S. Patents 2,153,553 or 2,188,465
suspension of polymer in an organic Solvent ,01‘
0r by contacting ethylene with water and a 10 to an aqueous dispersion thereof. Thepolymer
Deroxy compound catalyst, preferably a diacyl
containing the agent. or the Solution. emulsion,
peroxide or a dlalkyl dioxide, at temperatures of
or dispersion of polymer containing added agent
from 40° to 350° C. and at pressures in excess of
can be formed into any desired'shape
atmospheric, preferably in the range of 50 to
Through the use of the agents described here
1500 atmospheres, can be used_ The polymers of 15 in it has been found that three kinds of‘stabiliza
ethylene correspond in composition substantially
tion can be brought about, namely, stabiliza
to (CH2) I, have molecular weights in excess 01'
tion against heat-degradation, against light
4000, and soften 0r melt between about 100° c,
degradation, and against degradation upon out
and about 120° C. and their melting point is subdoor exposure.
stantially independent of their molecular weight, 20 In general, the amount of agent to be added to
On the basis of their known structure it wguld
the ethylene polymer depends upon the agent
be expected that these ethylene polymers would
used, and upon the degree and kind of stabiliza
show unusual stability to oxidative and other
tion desired.
The amount of agent added can
degradative agencies. It has been found, howvery up to 50% on the weight of the ethylene D01
ever, that when 'these ethylene polymers are ex- 25 ymer but as a rule it is preferred to use the mini
posed for prolonged periods to weathering agenmum amount required to achieve the desired re
cles, light or heat in contact with air, they Show
sults. The amount commonly used will vary from
severe degradation, as evidenced by loss in ten0.1 to 5 parts by weight per hundred parts eth
sile strength, elongation, and tear resistance.
ylene polymer
It is accordingly an object of this invention 30
In one form of practicing the invention the eth
to provide compositions comprising ethylene polylene polymer is dissolved in a hot organic hydro~
ymers, including its interpolymers, which have
carbon solvent, e. g., xylene, and to this solution
improved stability. Another object is to provide
is added the agent in amount sufficient to give 1%
compositions comprising ethylene polymers which
thereof on the polymer. These solutions are cast
in the form of self-supporting ?lms, molded arti- 35 on steel plates, the thickness of the ?lm is ad
cles, ?bers. or coatings have improved heat and
justed so as to give a dry ?lm of about 1 'mil in
light stability and improved durability upon outthickness, the solvent is removed by evaporation,
door exposure. Still another object is to provide
and, after drying, the ?lm is stripped from the
new compositions comprising ethylene polymers
plate
and as a minor component a substituted phenol, a 40
The examples which follow illustrate the utility
polyhydric phenol, an aryl amine, a long chain
and the outstanding advantages of this invention.
aliphatic amine, a heterocyclic compound conExample 1.—A solution of a polymer of ethyl
taining annular nitrogen, or a polymeric amino
one having an intrinsic viscosity of 0.55 (meas
nitrogen containing substance. Other objects
tired as a 0.125% solution in Xylene at 85° (3-)
will appear hereinafter,
'
,
The above objects are accomplished according
to this invention by incorporating into a normal-
45 and a calculated molecular weight of about 9,200
was prepared by dissolving 10 parts of the poly
mer in 90 parts of hot xylene. To this solution
ly solid ethylene polymer a small amount of an
was added a su?lcient amount of the agents list
agent such as a substituted phenol, a polyhydric
ed in Table I, to give 1% thereof, based on the
phenol, in any suitable'manner that will thor- 50 polymer. These solutions were poured over steel
2,434,602
3
4
plates and the ?lm thicknesses adjusted so as to
give a dry ?lm of about 1 mil in thickness. After
evaporation of the solvent the films were stripped
from the plate and exposed to heat. light, and
outdoor conditions. These ?lms were tested for
tear resistance both before and after various pe
riods of exposure. Typical results are shown be
low:
Table I
slot in the edge of the dim. Values are expressed
in units of grams to tear 2" of ?lm 1 mil in thick
ness, and represent the average or duplicate or
triplicate measurements.
In place 01' the substituted phenols oi’ the ex
amples there can be used bls(4-hydroxyphenyl)
dimethyl methane (diphenylol propane), bis(4
hydroxy - 3 - methylphenyl)
propane), bis(4-hydroxy-3-chloro
phenylidimethylmethane, bis(4-hydroxyphenyl;
methyiethylmethane,
None .......................... ..
Bis(2-hydroxy-4,6-dimethyl
,
1,000
500
hrs.
hrs.
67
64
23
57
63
33
bis(4 - hydroxyphenyl)
phenylmethane, bis(4-hydroxyphenyl) dipropyl
methaneI bis(4-hydroxy-3,5-dimethylphenyl) di
Stabilizer
inal
dimethyl methane
10 (dicresylol
Tea: Resistance Alter iade-ometer
Orig
,
pies and starting the tear from the end of a 115"
1,500
hrs.
methylmethane, 4-hydroxyphenyldimethylbutyl
~methane, 4-hydroxyphenyltriethylmethane, 4
hydroxyphenyldimethylisoamylmethane, and the
like.
Polyhydric phenols, in addition to hydro
The fade-ometer in which the above exposures 20 quinone, useful in the practice of this invention
were obtained was operated at approximately
include catechol, resorcinol, pyrogallol (1,2,3-tri
phony ) propyl methane ..... _.
hydroxybenzene), phloroglucinol (symmetrical
trihydroxybenzene), p,p'-dihydroxydiphenyl and
100° C. and 100% relative humidity.
Example 2.—-A polymer of ethylene‘was pre
pared by contacting ethylene containing 60 parts
the like.
per million of oxygen with water at a tempera 26 Aryl amines, in addition to those of the ex
ture of approximately 200° C. and at a pressure
amples, which are useful include octyl-phenyl
of 1,000 atmospheres. The polymer had a melt
amine, octadecylphenylamine, p,p'-diaminodi
viscosity of 0.02. One batch of the polymer was
phenylmethane, triphenylamine, alpha- and
untreated, a second milled with 2% phenyl-beta
beta-naphthylamines, decyl - beta - naphthyla
naphthylamine, and a third with 2% of hydro 30 mine, dodecyl-alpha-naphthylamine, octadecyl
quinone. Each batch was rolled into sheets of ap
proximately 1 mil in thickness and placed in an
beta-naphthylamine, symmetrical phenyl-naph
thyl-ethylene-diamine, symmetrical dinaphthyl
oven maintained at 100° C. An atmosphere of
air surrounded the products during the treat
ment. At the end of 4 weeks the products were
removed from the oven, moldings prepared, and
tensile and elongation measurements were made.
Original and ?nal values are given in Table II.
mine, and the like.
Long chain aliphatic amines useful in the prac
tics of this invention are those containing at least
Table II
2'7 Hydro
(fuinone
Orig. 4 Wks. Orig. 4 Wks. Orig. 4 Wks.
lbs. q.
strength,
‘
...... _. 2,(XX]
Elongation at
rea .......... -.
525
Melt viscoslty.....
0.02
8 carbon atoms. Typical members of this class of
compounds include dioctylamine, octadecylamine,
40
2'7 nhenyl-betr
No stamina
'iaophthylarninr
Tensile
ethylenediamine, diphenyl paraphenylenedia
850
1,800
l, 950
1,800
1,375
25
500
400
500
125
0.02
0.01
0.02
0.002
1 Inlusible.
Example 3.—A sample of polythene was milled
didodecylamine. octyldecylamine, dodecylamine,
dodecyltetradecylamine, dihexadecylamine, tri
butylamlne, and the like.
Heterocyclic compounds containing annular
nitrogen include the pyridines, dipyridyl, quino
line, melamine, and nitrogen bases extractable
45 from petroleum, those obtained from shale, or
obtainable by pyrolysis of cottonseed meal. These
nitrogen bases are complex mixtures of com
pounds and may be classi?ed in a general way
into aromatic bases, e. g., methylated quinolines
and hydroaromatic bases, e. g.. the pyrindacine
base CIBHZSN.
The polymeric amino nitrogen-containing‘ sub
stances are derived from ammonia or from mono
for one hour on a small rubber mill, the rolls of
meric amino nitrogen-containing compounds and
which were heated to 150° C. This operation was
repeated with the addition in one case of 0.1% 55 are characterized by being substantially insoluble
dicresylol propane to the polythene at the start
of the milling period and in the second case with
the addition of .01% 0t diphenylol propane. Suit
able samples for determining power factor were
prepared from the milled material. The power
factor at 3000 me. was .0011’! for polythene milled
in the absence oi.’ stabilizer, 00076 when dicresylol
propane was present during the one-hour milling
period and .00064 when diphenylol propane had
been added.
The tensile strength and elongation measure
in water and soluble in 2% aqueous acetic acid
ments described in Examples 2 and 3 were meas
ured on samples 1" long and 1/4" wide, and all
(2) Resinous reaction products oi’ amino ‘al
cohols and a substance from the group of acrylic
measurements were made in triplicate or more on
and alkacrylic acids.
and/or organic solvents.
The amino nitrogen
can be primary, secondary or tertiary and can
be part of an open chain or of a cyclic structure.
These polymeric amino nitrogen-containing sub
stances can be divided into sub-groups as fol
lows:
(1) Resinous reaction products of phenols,
aldehydes, and a material from the group con
sisting of ammonia, primary amines, and sec
ondary amines,
8. Scott pendulum type tester using a stretching 70
(3) Resinous reaction products of amino’
phenols with aldehydes.
rate of 20 inches/min. Results of tensile strength
are given in lbs./sq, in. and elongations are in per
(4) Reslnous reaction products of alkyl ke
cent to break.
tones with formaldehyde and a substance selected
Tear resistances were measured on an
from the group of ammonia. primary amines.
Elmendort type tear tester, using 1" square sam 76 secondary amines. and tertiary amines.
2,434,662
5
(5i Resinous reaction products of diaryl guani
dines with aldehydes, especially formaldehyde.
(6) Resinous
reaction products
of diaryl
guanidines with aldehydes, especially formalde
' hyde, and either a primary or a secondary amine.
(7) Resinous reaction products of aryl amines
with aldehydes or ketones.
-
(8) Resinous reaction products of vinyl ketones
with either ammonia or primary or secondary
amines.
‘
(9) Resinous reaction products of phenols}
piperazine, and aldehydes, especially formalde
hyde.
(10) Resinous reaction products of dimethylol
urea dimethyl ether with amines.
(11) Resinous reaction products of polyvinyl
chloroacetate with secondary aliphatic amines.
(12) Resinous
reaction
products
of
urea,
formaldehyde, and aliphatic primary or second
The compositions of this invention can be
extruded about wire orother electrical conduc
tors, or they can be formed into tapes or ribbons
and applied about the wire or other electrical
conductor.
'
In the above electrical use the compositions of
this invention can be employed as such or they
can be modi?ed with such materials as pigments,
?llers, para?in wax, or polymeric materials such
10 as rubber, hydrogenated rubber, polyisobutylene,
polystyrene, polybutadiene, etc.
The remarkable stability against heat ofthe
compositions of this invention renders them more
suitable than unstabilized ethylene polymers for
melt extrusion of ?lms, ?bers, ?laments, and
coatings, or for other melt manipulations. The
physical properties of objects prepared from
ethylene polymers by melt manipulation are in
ary amines containing less than» 5 carbon atoms. 20 ?uenced by the temperature used. Tempera
tures above 185° C. are preferred, providing that
(13) Reaction products of phenol-lignln with
degradation of the polymer can be avoided. Un
dimethylamine and formaldehyde.
(14) Resinous reaction products obtained by
stabilized compositions suffer serious degrada
tion at such temperatures, even when practical
precautions to exclude oxygen from the polymers
25 have been taken. However, the stabilized, com
containing resins.
positions of this invention are resistant to
Combinations of two or more of the agents
degradation under these conditions. Such ?lms
can be added to the ethylene polymer, particu
the catalytic hydrogenation, in the presence of ,
ammonia or a primary amine, of ketone group
are useful as unsupported ?lms or in coatings or
laminations, while the ?bers or ?laments can be
30 knitted or woven into valuable fabrics, tubings,
The agents of the invention are effective in
etc.
larly when stabilization against more than one
degradative agency is desired.
protecting the ethylene polymers against degrada
We claim:
tion catalyzed by copper and its compounds.
1. A composition of matter comprising a nor
Because of their excellent stability the ethylene
polymers containing the agents of this invention 35 mally solid ethylene homopolymer and from 0.01
to 5 parts by weight of a compound selected from
are advantageously used as binders, coatings, and
the group consisting of diphenylol propane and
. impregnating agents in the manufacture of elec
dicresylol propane.
'
trical insulating materials. In sheet form the
2. A composition of matter comprising a nor~
compositions of this invention can be used as
condenser plate separators, as separators in stor 40 mally solid ethylene homopolymer and 0.1% by
weight of dicresylol propane based on the
age batteries, and as separators for the layers
ethylene polymer.
_
of coils in transformers, and also as external
insulation on all sorts of coils such as are used
3. A composition of matter comprising a nor
mally solid ethylene homopolymer and 0.1% by
in electrical machinery, radio, telephone, tele
of diphenylol propane based on the
graph, and miscellaneous electrical and elec 45 weight
ethylene polymer.
tronic apparatus.
4. A composition of matter comprising a nor
In the form of sheets the compositions of this
invention are valuable as so-called slot insula
tion in dynamo electrical machines such as mo
tors and generators. In dynamos the connect 50
ing coils are positioned in slots which are formed
in the magnetic core and which are lined with
suitable insulation. Machines of this type are
mally solid ethylene homopolymer and from 0.01
to 5 parts by weight of diphenylol propane per
100 parts of polymer.
5. A composition of matter comprising a nor
mally solid ethylene homopolymer and from 0.01
to 5 parts by weight of dicresylol propane per
100 parts of polymer.
improved when the coil insulations, the slot lin
ing, or both, comprise the compositions of this 55
GEORGE H. LATHAM.
invention. The connections between the coils
DANIEL E. STRAIN.
‘and the so-called end-windings are preferably
insulated with the compositions of this inven
REFERENCES crrnn
tion. The connections between the coils may be
The following references are of record in the Q
covered 'by a sleeve which is preferably composed
of the compositions of this invention in order 00 file of this patent: ‘
that the sleeve may have the desired ?exibility,
UNITED STATES PATENTS
insulating properties, and permanence. Sheets
Number
Name
Date
may be punched into segments of the proper
2,270,959
Murke __________ __ Jan. 27, 1942
shape as spacers between commutator bars of
Hop? __________ __ Nov. 16, 1943
automotive, aero and like motors and generators 65 2,334,195
2,336,195
Sparks _____ _______ __. Dec. 7, 1943
for direct current and for alternating frequency
currents. Motors of this kind are particularly
OTHER REFERENCES
. useful in devices and locations where the ma
chines are exposed to conditions abnormally de
stru'ctive to conventional insulation.
Swallow, Endeavour, vol, 3, pages 26-31 (Jan.
70 1944).
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