Note: Descriptions are shown in the official language in which they were submitted.
~ 3 7 3 2
FL~IE RETARDA.'`"r CROSSLIr:;;ED
P OLY OLE l~ s ~ I O`; ~ TE F~I AL
The present invention relates to cross-
linkable polymerlc compositions ~hich exhibit moisture,
heat and flame resistance and which are useful in
producing insulated wire and cable as well as molded
products. More particularly, it relates to an ethylene-
vinyl acetate copolymer composition having a high
1 degree of flame retardancy.
One of the most important areas where fire
resistant polymer compositions find use is in the
electrical environment, i.e., where both insulating
and fire resistant properties are sought, most
especially in the area of conductor insulation. At
one time, extrudable compositions available to the wire
and cable art were required, for flame resistance, to
contain halogenated polymers such as chlorinated poly-
ethylene, polyvinyl chloride, chlorobutadiene,
chlorinated paraffin, etcO, together with antimony
trioxide, both components being present in sizable
quantities. Alternatively, a coating of chlor~sulfonated
polyethylene paint was applied to a non-flame retardant
insulating compound which constituted an additional
manufacturing operation.
For certain types of dry transformers,
particularly high voltage transformers, a problem
existed in that electrical failures occurred due to
surface creepage of the organic insulating compound
3 used. The problem was solved through the addition
--2--
1 of h~drated alumina to compositions ~hose organic
binder consisted of butyl rubber, epo~ resins or
nolyester resins. However, these compositions do
not possess a balance of e~cellent e~:trudability
characteristics, physical and electrical properties,
heat resistance and flame retardance. Such co~positions
are disclosed in U.S. Patent Nos. 2,997,526; 2,997,527
and 2,997,528 to Kessel et al. The described compo-
sitions for such usage have poor tensile strength,
elongation and percent elongation retained after aging.
~ ire retarding polymeric compositions
exhibiting, inter alia, improved moisture and heat
resistance consisting essentially of an intimate
mixture of at least one cross-linkable polymer
containing as a major component an ethylene-vinyl
acetate copolymer, one or more silanes and one or
more hydrated inorganic fillers have found wide
acceptance in the wire and cable art. Compositions
such as these are disclosed in U.S. Patent Nos.
20 3,832,326 and 3,922,442 of North et al. These patents
disclose compositions which contain 80 to 400, preferably
125-140 weight parts of filler per 100 weight parts
of polymer and 0.5 to 5~0 parts of silane per 100 parts
of filler. No specific concentration range of lubricant
is disclosed although 2 parts of calcium stearate per
100 parts of polymer are utilized in all of the fourteen
compositions of the examples.
The prior art polymeric compositions of North
et al., exhibit a balance, of improved physical and
electrical properties together with a high degree of
1 flame and ~ire retardance. These highly desirable
results are achieved ~ithout the use of halogenated
polymers such as polyvi~yl chloride and chlorosulfonated
polyeth~lene, thereb~ eliminating hydrogen chloride
5 fumes; without carbon black, thereby permitting its
use as colored insulationS; without any flame retardant
coatings such as are currently required, therby elimin-
ating an additional step in manufacturing operations
when the compositions are used as, e.g., insulating
compounds extruded onto a conductor.
Such compositions find particular use as
white (an inherent property) and colored uniinsulation
compositions, which can be extruded over metal, e.g.,
copper or aluminum, conductors, to provide a single
layer insulating and jacketing composition which is
rated according to U.L. standards for 90C. operation,
and in some cases operation at temperatures as high
as 125~, at up to 600 volts~
The insulating compositions of North et al.
have found particular utility in the insulation of
switchboard wire, appliance wire, and automotive wire
where a unique combination of superior electrical
properties combined with resistance to the degradative
effects of heat and flame are essential, and where
low smoke density and non corrosive fumes are desirable.
North et al. -ontemplate ethylene-vinyl acetate
copolymers in their compositions crosslinked by irradiation
with high energy sources or through the use of chemical
crosslinking agents. As has been observed with other
radiation cured polymeric compositions, radiation cured
1 compositions ~repare~ i~ accordance with the dis-
closures of North et al. have poorer physical strength
properties than their peroxide cured counterparts.
The reasons for this are not fully understood although
5 the precise nature and amount of the major and minor
components in the composition are thought to be a
contributing factor. Several modifications were
made to the peroxide curab]e product to produce the
radiation curable counterpart. The copolymer in the
10 radiation curable product has a higher vinyl acetate
content and aluminum stearate has been substituted
for the calcium stearate lubricant. Although this has
improved the physical strength of the radiation cured
composition over what it would have been, it is still
15 significantly lower than the peroxide cured product.
U.S. Patent No. 4,349,605 issued September 14,
13~2, describes a radiation cross-linked polymer compo-
sition having improved physical strength properties sub-
stantially similar to a chemically cross-linked counter-
20 part. The improved physical strength properties areachieved by the use of increased amounts of silane and
the substitution of the lubricant Mold Wiz for the aluminum
stearate lubricant.
Besides the three essential components,
25 other additives can be incorporated into the composi-
tions of North et al. to provide certain desirable
qualities. Included in these additives are pigments,
antioxidants and stabilizers.
Antioxidants are included to inhibit polymer
30 degradation resulting from oxidation which proceeds
by a free radical chain mechanism. The antioxidants
act either to tie up the peroxy radicals so that free
* Trade mark
--5--
1 radicals are incapable of pro~ag2tlnc the reaction
chain, or to decompose the hydropero~;ides in such a
manner that carbonyl groups and additional free radicals
are not fo~ned. The ~ormer, called chainbreakin~ anti-
oxidants, free radical scavengers, or inhibit~rs, usuallyare hindered phenols, amines, and the like. The latter,
called pero~ide decomposers, generally are sulfur
compounds (i.e., mercaptans, sulfides, disulfides,
sulfoxides, sulfones, thiodipropionic acid esters
and the like), or me~al complexes of dithiocarbamates
and dithiophosphates
The art also shows stabilizers ror synthetic
resins such as in V.S. Patent No. 4,279,805 which
describes an alkylene bis-thioalkanoic acid amide as
a stabilizer, and corrosion inhibitors as, for example,
described in U.S. Patent No. 4,124/549 to Hashiudo et
al.
Another disclosure, U.S. Patent No, g,255,303
t~ Keogh, shows a composition for electrical applications
having electrical resistance, tensile strength, and
elongation capability which includes ethylene-vinyl
acetate, halogenated flame-retardant, antimony trioxide,
peroxide and zinc stearate. U.S. Patent No, 4,035,325
to Poppe et al describes a combination in which the
effectiveness of flame retardant combinations of
antimony trioxide and a halogen-containing compounds
such as hexabromocyclododecane (HBCD), chlorinated
paraffins, tetrabromophthalic anhydride (TBPA), and
tetrabromoterephthalic acid (TBTA), is purportedly
3 increased by the addition of certain organometallic
compounds which have the chemical structure of either
substituted hydrazines or substituted 3-amino-1,2,4~triazole
amides.
~2~
1 B~ the present i~ve.~;ion there i5 provided
a polymexic composition ~ith a lub-icant system ~hich
aiso significantly increases the flame-retardancy of the
composition.
r
In accordance ~ith the present invention,
it has bee~ found that a significant flame-retardant
~uality can be achieved in ethylene copolymer (particu-
larly ethylene-vinyl acetate copolymers) compositions
containing silane-treated hydrated inorganic fillers
by the use of a lubricant composition comprising a
fatty acid having 8 to 25 carbons atoms and an
alkylene-bis-amide wherein the alkylene group has
from 2 to 8 carbon atoms and the amide constituent
has from 8 to 25 carbon atoms, such lubricant compo~
sition, preferably used in combination with antimony trioxide
and a halogenated flame retardant additive in addition
to the normally flame retardant hydrated alumina.
Specifically, the present composition includes the use
of the abo~e-descxibed lubricant composition in lieu
of the normal calcium stearate lubricant normally used
in the above-described combinations~ ~ore particularly,
this invention is directed to a crosslinkable pol~meric
composition comprising:
a) a copolymer of ethylene and a vinyl
ester of a C2-C6 aliphatic carboxylic acid, a Cl-C6
alkyl acrylate or Cl-C6 alkyl methacrylate,
b) from 80 to 400 parts of hydrated inorganic
filler per 100 parts of copolymer,
3 c) .4 to 8, and preferably 0~8 to 4, parts of an
alkoxy silane per 100 parts of hydrated inorganic filler, and
d) an antiflame component containing a
halogenated flame retardant, antimony trioxide in
addition to the normally flame retaxdant hydrated
inorganic filler, and, quite surprisingly, a dual
-7
1 lubric~nt system comprislny a fatty acid having from
8 to 25 carbon atorns and ~n alkylene-bis-amide wherein
the alkilene group contains from 2 to 8 carbon atoms
and the amide groups contain from 8 to 25 carbon atoms.
The present invention can also be described
as being concerned with an improvement ln a cross-
linkable polymeric composition of the type containing
a) a copolymer of ethylene and a vinyl
ester of a C2-C6 aliphatic carboxylic acid, a Cl-C6
alkyl acrylate or a Cl-C6 alkyl methacrylate, and
b) a silane-treated hydrated inorganic
filler, the concentration of said filler being 80
to 400 parts of filler per 100 parts of copol~mer,
c) halogenated flame retardants, and
antimony trioxide
which comprises utilizing as an unusually effective
flame retardant a dual lubricant system comprising
a fatty acid of from 8 to 25 carbon atoms and an
alkylene-bis-amide in which the alkylene group contains
from 2 to 8 carbon atoms and the amide groups contain
from 8 to 25 carbon atoms.
This invention also relates to an electrical
conductor coated with a uniinsulating layer comprising
these crosslinkable polymer compositions.
The present i,~-vention relates to crosslinkable
polymeric compositlons comprising copolymers of ethylene
and a vinyl ester of an aliphatic carboxylic acid, an
alkyl acrylate or an alkyl methacrylate and a silane-
treated hydrated inorganic filler which when used with
1 a dual lubrlcant s~stem as described above in combination~ith ant~mOny trioxide and haloaenated and non-halogenated
flame retardants possesses very high flame-retardant
characteristics. These compositions find particular
utility as wire and cable insulation.
The compositions of this invention contain, in
addition to a particular lubricant combination, one or
more haloqenated flame retardants and, optionally antimony
trioxide, one or more crosslinkable or curable ethylene
copolymers, one or more silanes and one or more hydrated
inorganic fillers. The copolymers, silanes and inorganic
fillers include those disclosed in U.S. Patent Nos.
3,832,326 and 3,922,442 of North et alO
The terms crosslinkable or crosslink~ing are
ascribed their normal art recognized meaning in the
present specification, i.e., they denote the formation
of primary valence bonds between polymer moleGules.
Crosslinking can be accomplished by any of
- the known procedures such as chemical means including
peroxide crosslinking; by radiation using cobalt -
60, accelerators, ~ -rays, ~-rays, electrons, X-rays,
etc.; or by thermal crosslinking. The basic procedures
for crosslinking polymers are extremely well known to
the art and need not be described here in detail.
The polymeric component of the present compo-
sition is a copolymer of ethylene and a comonomer which
may be a vinyl ester, an acrylate or a methacrylate.
The vinyl ester may be a vinyl ester of a C2-C6 aliphatic
carboxylic acid, such as vinyl acetate, vinyl propionate,
- 9 -
1 vinyl but~rate, vinyl pentanoate o. vinyl hexanoate.
The acryla~es and m~thacrylates may be any of the
Cl-C6 alkyl esters including, for example, methyl,
ethyl, propyl, butyl, pentyl or hexyl acrylate or
methacrylate. The preferred copolymer com?risin~ the
polvmeric component of this invention is an ethylene-
vinyl acetate copolymer containing about 6 to about 90%,
preferably about 9 to about 40~, most preferably
about 9 to about 28~, vinyl acetate, balance ethylene.
Although little is gained, and some properties
are even harmed, it is possible to include minor pro-
portions of other crosslinkable polymers or copolymers
in the composition of this invention. However, ethylene
copolymers, preferably, ethylene~vinyl acetate copolymers,
as described above, should comprise at least about 66%
of the total polymers present. Representative of such
minor polymeric components which can be used in such
non-preferred embodiments include polyethylene,
copolymers of ethylene with propylene, butene, the
acrylates and maleates, polydimethyl siloxane and
polymethylphenylsiloxane, copolyme~s of vinyl acetate
with the acrylates, etc. Obviously, mixtures of these
minor polymeric components can be used.
Terpolymers of ethylene and vinyl acetate
derived from, e.g., any of the corresponding monomeric
materials listed above (other than ethylene or vinyl
acetate) can be usedO A representative terpolymer
would be an ethylene-vinyl acetate-vinyl maleate ter-
polymer.
The ethylene-vinyl acetate copolymers used
~10-
in our invention prefer2bl~ have a melt inde;~ of from
about 1.0 to about 20Ø
The polyeth~lenes useful in the present
invention include essentially all high, medlum and low
density polyeth~lenes as well as mi;tures thereof.
The most preferred polyethylenes for blending for use
as uniinsulation for electrical wires and cables generally
have a density of from about 0.900 to about 0.950 gm./cc.
and a melt index of rom about 1.0 to about 10Ø
Specifically, the compositions of the present
invention provide a highly flame retardant composition
surprisingly by use of a dual lubricant combination
while retaining other desireable characteristics
including an unexpected balance of:
1~ low temperature brittleness, i.e., the
com?osition will not readily crack during low temper-
ature movement (ASTM D 746).
2. heat resistance after aging, i.e.,
excellent elongation after extended service at 90C.
and even 125DC.
3. arcing and tracking resistancel as high
as 5 KV, whereas even porcelain shows surface break~
down at 4 KV. This property is not often required,
however, in the preferred environment of under 600
volt service.
4. moisture _esistance, i.e., low mechanical
absorption of water which yields a superior dielectrical
constant.
5. resistance to industrial chemicals.
6. resistance to oil and gasoline or diesel
fuels.
ll -
1 I~ is not kno~n wh~ the cor~os1tlons of
this invention provide such a s~perlor balance of
properties. It is possi~le that there is some
synerglstic relationship between the ethylene-vinyl
acetate copolymer, silane and hydrated inorganic
filler, but there is no intention to be bound by
such a theory. However, it has been established
that for low voltage environments, less than S000
volts, ev~n more particularly for less than 600
volt environments, the compositions of this invention
are particularly useful for service as uniinsulation.
Uniinsulation is an art accepted term denoting in-
sulation where one layer is extruded around the
conductor, and this one layer serves as the electrical
insulation and the jacketing to provide physical
and flame protection. The present compositions are
especially adapted for service as uniinsulation in
the under S000 volt range, and most especially in the
under 600 volt range, where only a single extruded coating
is used, and it is in this environment that a superior
balance of properties is required. It has been further
found that ethylene-vinyl acetate copolymers will
hold very large amounts-of filler and still provide
high fle~ibility and a high degree of crosslinking.
The simultaneous achievement of high filler loading,
- flexibility and crosslinking is quite surprising as
high fle~ibility and high crosslinking were generally
believed incompatible, as are high crosslinking and
high filler loading (which implies low crosslinkable
3 polymer content). Ethylene-vinyl acetate copolymers
~.Z'~
-12-
further provide superior fire retardanc~ to the
polymeric compositlons of the present invention.
The above described ethylene-vinyl acetate
copolymers may be crosslinked by irradiation with
hlgh-energy electron beams or through the use of chemical
crosslinking additives. ~ully crosslinked, these
pol~ers become thermoset in behavior. In the pre-
fe-red compositions of this invention, chemical cross-
linking is preferred, particularly where superior
physical strength is xequired.
Chemical crosslinking is accomplished by
incorporating a crosslinking agent, e.g., dicumyl
peroxide or alpha, alpha' bis(t-butylperoxy) diisopropyl-
benzene, into the ethylene-vinyl acetate copolymer.
The peroxide is later activated during processing to
link the ethylene-vinyl acetate polymer chains into
a three-dimensional network (and other minor amounts
of crosslinkable polymer, if present).
The chemical crosslinking is carried out in
accordance with procedures well known to the art, and
variations in the general cross-linking conditions set
out below will be apparent to one skilled in the art.
The present invention is moreover, not limited to the
use of tertiary organic peroxides for chemical cross-
linking, and other art recognized materials which de-
compose to provide free radicals can be used. Obviously
such crosslinking agents should not be decomposed duxing
compounding of the composition, but the selection of
acceptable cross-linking agents will be apparent to
those skilled in the art.
_13_
1 Generall~ spea};ing, as the amount of cross-
lin!~in~ aq~nt used increases, the de~ree of polymer
crosslin~;inq increases. ~sually no more than 10~
(based on polymer) o~ ~he organic tertiary peroY.ides
r, ~eed be used, with 3 to 6~ beins more typical values.
Otner crosslin};ing agents may require different amoun~s,
but these can be readily determined. It is often
advisable to avoid very low amounts of crosslinking
agents, since some loss of resistance to deformation
under sudden or continuous pressure may ensue. Cross-
linking coagents such as triallylcyanurate and the like
may also be included to increase the effectiv2ness of
the crosslinking agent.
The tertiary organic peroxides, as with most
1~ other chemical crosslinking agents, are activated by
heating to above their activation temperature whereupon
decomposition thereof occurs. Any of the known procedures
can be used to accomplish activation, e.g., high pressure
steam application to the composition.
The art of radiation crosslinking is so highly
developed that little need be said with respect to
such procedures. As higher total doses of radiation
are used, the degree of crosslinking generally increases,
and for preferred cxosslinkings a total radiation dose
2~ of about 5-25 megarads will be used.
Crosslinking _ generally conducted at above
atmospheric pressures, e.g., on the order of 200 to ~00
psi, although higher or lower pressures may be used.
Pressure is necessary when curing with steam to obtain
the required temperature for activation of the pero~ide
catalyst. With high temperature gas curing, pressure is
~.~2~
-14~
1 desired to avoid porosi~y in ~he insul2tion. Porosity is
hlghly un~esirable in electrical lnsulatlon since it lowers
ele_trical insulation pro~erties and can cause premature
failure fro~n corona.
In general, the hianer the de_ree o~ crosslink-
ina the more resistant the polymeric comDosition is to heat,
moisture, chemical reagents, changes tith aaing and
environmental conditions, etc., and usually abrasion. At
lower degrees of crosslinkins there is also some loss of
heat resistance as well as pronounced e~fect on percent
elongation after agina. The exact degree of crosslin~ing
can, of course, be varied to take the above factors and
their effect on the final product into account. Although
higher or lower values can be used, for ~ire and cable
insulation a crosslinking percentange on the order of
about ~5-95% for ethylenevinyl acetate is generally pre-
ferred, determined by extraction weight of soluble com-
ponents in the cross-linked polymer.
One or more substituted silanes comprise the
second essential component of the polymeric compositions
of the present invention.
Any silane may be used in the present invention
while will not adversely af~ect the desired balance of
properties and which will help to bind the polymer and
inorganic filler of the present invention, provided that
the silane does not make the composition combustible and
does not interfere with polymer crosslinking or degrade
during polymer processing, e.g., alkoxy and amine silanes.
The preferred silanes used in forming the insu-
lating compositions are the alkoxysilanes~ e.g., lower
alkyl-, alkenyl-, alkynyl- and arylalkoxysilanes as well
as the lower alkyl-, alkenyl-, alkynyl-, and aryl-
-15-
1 al};oxvalko~ or ar~lo~al}:~l5ilane5. Specific
e~amples of such s:ilanes are methyllriethox~-, methyltris
(2-methoxyetho~)-, dimethvldietho~-~ alk~l-trimetho~-,
vin~ltris(2-methoxyethOxv)-l phen~l-tris(~-methoxvethox~
5 vin~ltrimethoXy- and vinyltriethos~rsilane.
It is preferred to use the vin~lsilanes for
best results, and of the vin~lsilanes the follo~ing are
especiall~ preferred:
gamma-Methacryloxyprop~ltrimethoxysilane
CH o
1 3 1l
H2C - C _ C _ O(cH2)3si(OcH3)3
and
Vinyl-Tris(2-~ethoxyethoxy)Silane
2C CHSi(OC~2CH20CH3)3
The fillers used in the present invention are
the hydrated inorganic fillers, e.g., hydrated aluminum
os:ides (A1203 3H20 or Al(OH)3), hydrated magnesia,
hydrated calcium silicate. Of these compounds, the most
preferred is hydrated aluminum oxide.
To obtain the superior balance of properties
described, it is mandatory that a hydrated inoraanic
filler be used in formulating the polymeric compositions
It must be emphasized that large proportions of another
type of filler, be it inert or not, cannot be added to
LB~
-16-
1 the compositions an~ still achieve the superior b~lance
of properties.
The water c, h~dration in the inorganic filler
must be released durlns the ap?lication of heat sufficient
to cause combustion or ignition of the ethylene-vinyl
acetate copolymer. The water of hydration chemically
bound to the inorganic filler is released endothermically.
It has been found that the hydrated inorganic filler
increased flame retardance in a manner far superior to
other fillers previously used by the art to provide
insulation with flame retardance, e.g., carbon black
clays, titanium dioxide, etc. What is even more
surprising is that flame retardance is combined with
excellent electrical insulation properties at the high
filler loadings used, since at these loadings the
copolymeric composition contains a large amount of
bound water.
The filler size should be in accordance with
those sizes used by the prior art.
An antioxidant composition which can also
be included as a component of the polymeric compositions
of the present invention includes a diester of thio-
dipropionic acid, the preferred diester being distearyl-3,
3' thiodiproplonate (DSTDP). It has been found
that the use of two different types of antioxidants
provides effective oxidation inhibition. Thus, a mixture
of an antioxidant of the chain breaking type and one
which is a peroxide decomposer provides a very effective
antioxidant composition. Therefore, with DSTDP, which is
: ~z~
~17
l a known pero~:ide decomposer, an zmine or a hindered
phenol may be effectively em?loyed as an antio;:idant
com?osition. Among these free radical scavengers,
the stearicall~- hindered phenols are especially effective.
~seful phenols include the alk~lated phenols, the
alkylidene - bis-alkylated phenols and the polyphenols.
Specific examples thereof include 2, 6 ditertiary
butyl-para-cresol, octadecyl 3, 5-di-t-butyl-4-hydroxy-
hydrocinnamate, 2, 2'-methylene bis(6-t-butyl-4-methyl
phenol), ~, 4'-butylidene bis (6-t-butyl-3 methyl phenol),
1, 3, 5-trimethyl-2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxy-
benzyl) benzene and tetrakis (methylene (3, 5-di-t-butyl-
4-hydroxy-hydrocinnamate) methane with the latter being
particularly preferred.
~5
When polymeric insulation is formed on~
conductors by extrusion, it is preferred that a
lubricant form a portion of the insulating composition.
Such lubricants as a fatty acid soap or a metallic
derivative thereof have been used heretofore. The
lubricant not only aids in the e~trusion process but
it also improves the stripping properties of wire
insulation thereby facilitating the task of the end-user.
The lubricant component comprises an essential
component of the polymeric compositions of this invention.
It has been found that ;e combination of antimony
trioxide and a halogenated flame retardant in addition
to the hydrated filler in the required concentration,
plus a particular two component lubricant composition
provided in a lubricating effective amount,unexpectedly
provides the crosslinked compositions of the present
18
1 in~ention ~ith exceptionall~ qood flame-retard2n'
properties.
Calcium stearate has often been employed
heretofore as 2 lubrican' fo~ polymeric compositions
s~^~ as those of North et al. Now, however, it has
been found that a lubricant composition comprising
a ~a'ty acid such as lauric aci.d and a alkylene-bis-
a~ide such as ethylene-bis-stearamide, especially
when used in combination with antimony trioxide and
halogenated and non-halogenated flame retardants,
will produce a crosslinked composition with signifi-
cantly enhanced flame retardant properties.
The dual lubricant composition of the present
invention comprises a fatty acid of from 8 to 25
carbon and an alkylene-bis-amide having the general
formula:
R' ~ R'
\ N-R-N
H /
wherein R = a divalent alkylene radical of from 2
to 8 carbon atoms; and
R' - -C-R , wherein R is an aliphatic radical
having from 8 to 25 carbon atoms,
in a proportion of from about 1:1 to about 1:6 of fatty
acid to akylene-bis-amide, and preferably in a proportion
of about 1:3 acid to alkylene-bis-amide. Preferably the
dual lubricant composition comprises 25 percent lauric acid
~2il~
--19--
1 and 75 p~rcent eth~lene-bis-stearamide. Tne total amount
o dual lubricant composition shoul~, be fro~ about
.01 to about 10 Dercent b~ weight o~ the total poly~eric
com?osition, and ~referably from about 0.; to about 3
percent.
It has been found that the dual component
lubricant composition is especially effective in a
peroxide curable polymeric composition when used in
combination with antimony trioxide, and halogenated flame
retardants such as ethylene-bis-tetra-bromophthalimide,
deca-bromodiphenyl oxide, etc. The antimony trioxide
is included in an amount of from about 2 to about 20
percent by weight and preferably from about 4 to about
8 percent by weight, and the halogenated flame retardant
is included in an amount of from about 5 to about 30
percent by weight, and preferably from about 8 to about
14 percent by weight of the total polymeric composition.
The amounts of polymer and filler in the compo-
sition of this invention can be varied within the wide
proportions. The silane percentage should be in the range
of from about 0.5 to 5.0 parts per 100 parts of polymer.
; 25 Lower amounts may be insufficient to provide adequate sur-
face treatment while larger quantities could have an
adverse effect on some of the physical properties, i.e.,
elongation, of an extruded insulating compound after
crosslinking.
3o
- ~o -
1 Best results are obtalned in coa'ing, e..,
e~:truding, onto electrical wlres and cables when from
80 to 400 or more weight part5 c r filler (most preferable
at least 12~-150 weight p2rts), 0.~ to 5.0 weight parts
5 of silane and 100 weight parts of polvmer are present.
~ he composition of the ?resent invention may
be formed in a number of ways. However, in every
instance it is necessary that the filler and polymer
be in intimate contact with the silane when dispersion
of the filler in the polymer is initiated. This can be
done in an internal mixer, such as a Banbury or Werner
& Pfleiderer extruder.
Any processing device known to the art which
insures an intimate mixture of the essential components
may be used, provided the silane couples the hydrated
inorganic filler to the polymeric com?onent.
It will be apparent that in addition to the
essential components of the compositions of this inven-
tion, other additives may be present, e.g., pigments,
stabilizers, so long as they do not interfere with
crosslinking, when desired, or harm desired properties.
Such materials are present in very minor proportions,
ranging from less than 10% of the polymer, and usually
in amounts of less than 5%. There are two reasons amounts
of other components are not desirable; firstly, the
present composition per se has such superior properties;
secondly, any significant amounts of other fillers
îor example, serve only to degrade or upset the balance
or properties.
For the formation of insulation on conductors
by extrusion, a lubricant such as a fatty acid soap
or metallic derivative thereof has in the past been
utilized with success. Such materials has also improved
p~
the strlppinc3 properties ~ wlre insulatlon and thereby
~er~it the insulation to be easily stripped from the
wire by the user to facilitate splicins and to make
ter~,inations. It has been the practice to use acceptable
- soaps such as the alkaline earth metal fatty acid soaps,
a preferred soap being calcium stearate. Additional
representative examples of such lubricants include the
alkaline earth metal salts and aluminum salts of stearic
acid, oleic acid, palmitic acid and other fatty acids
used by the art for this purpose, silicone oil, long
cnain aliphatic amides, waxes, etc. Now, however, it
has been ~iscovered that the dual lubricant system of
the preser.t invention serves not only as an effective
lubricant but also enhances flame retardant properties,
especi~lly when used with a halooenated flame retardant,
an,imony trioxide, and a non-halogenated flame retardant
in z peroxide curable polymeric composition.
The following examples are provided to further
illustrate certain aspects of the invention.
; 20 A number of crosslinkable polymeric compositions
shown in Table 1 below are prepared in which the lubricant
used was calcium stearate. (The numbers in the tables
- indicate parts by weight).
Each of these compositions were extruded onto
14 AWG wire and subjected to Underwriters Laboratories
Flame Retardant ~ rtical-Wire) test (UL FR-l).
The results of the UL FR-l tests conducted on
the samples which included calcium stearate are shown
on Table II.
~2~118~
--22--
o ¦ N N C' N O O N O
O ~
O O ~1 N N O O ~ ~ O O N O
0~ O N
_ ~ O
U'l ON N 0 0 ~D N O O N O
O
_ . ~
0 ~¦ ~ ~ ~ ~ ~D N O O N O
~r
U~ ~ O ~ ~ O O U~ ~O O ~ O
~ ta
o o o N ~ O O 1~ N OO N 0
~ a~ N O 1'- -- ~
Ul Ul
.' 5
~ O O O N N O O U~ NO O N O A 0~
c o o N N O O Ir~ ~O O N O o ~i ~
1'`11 N O O ~O NO O ~ O ~ R U
X ~ ,1
O ~; h
O O O N ~ O O Ir~ N O O N O ~ ~1 ~
O O
h h ~ .. .
3o ,_, O o.,l
~ V ~ c h-
C~ N C~ 1~1 0 E V t ~ 10 U~ ID ^ Q)
C r ~ V ~0 W ~ ~ Q~ a) Lll
e ~a C ~U X ~ c ~ E o- ~'a 'IS O
~' * t) ~ V o ~ o ~ C L- O
u E C)--4--I X é' E~ r~ o V o
O '~ C'L V ' U ,, ~ Oo U '~ a: E ~ U ~ lc
h ~ Q O c~ N * #
¢ ,C v g Q ',~ ~c *
N O o 11~ t~l o o (~1 0
5 --¦ o o N N O O V. ~`J O O ~1 0
r~ ¦ O O O N N U~ O It~ ~ O O ~ O
~D ¦ O O O ~ ~ u~ O Y~ N O O ~ O
--¦ '`' N O O ~D ~ O O ~ O
-
~rl o o o ~ o o u) ~ . o o r~l O
U ~-r
20 ~
~'- ¦ O O O ~ NO 0 117 N O O 1`' O
2 5 ~ ¦ N ~ vl N O O N O
--¦ O O U'l NN O O ~ O O N O
C
O C .~ Q)
z ~ c ~ h~
~ ~ 0 ~ ~ C ,~, ,~,
~ ~ ~ xoal C I C~ 4 ~ ~ ~ " I E o~
~ 1X E~ Ec~ o
~ ~ O ~ o U'X ~ ~ U ~ O
~ . ~ ~ ~ a o c~ c ~ ---- N
4 ~ ~ U ~ 4 ~ ~
--2~--
O c
O C) C) ~ Z ~ ~'q Z ('q I~q
~ 0 z z 0 0 z 0 0 z z 0 0 z z z z 0 z 0 0 0
u~
L
l O 3 . r~ ~ Z Z a~ a~ Z Z z Z ~'q
s~1
u, m
H
H J ) J ¦ r1 O O O O O O O O O O O O O O O O O O O O O
~:
E-~ ~ r
r~
~ r 1~; ct) O O ~ O O O O c~ O t~
r--
5 t~
L ) O ~ O O t~l O r~l O O O ~ ) O r-l O O O
r--I .a~ U~ O O O C ~ O t~ ') O 1~ 0 r~) O O O O O O O O O
t,q
~q
C)
~J 5
c a~ o a~ a~ o o o
V r--~
tq Q
E
U~
~2~
--2:~--
~n ~
r~ I n~ C r r~, r
O _
V J tn tn tn ~ ~n Cl CI ~ tn C tn tn U, r~ C~ ~ trJ tr
O ~' ~ ~ ;~ ~ ~ ~ ~ >~ ~ ~ ~ ~ ~1
v~ _ I
z z zO O O z O O C O O O ~ J U~ O O U O U O
tn
a)
0 3 r~ U U t~ O U O U U U U O O U U U tr tr U O tn U
~) ~
~1
Ooo OOo ooO ooo ooo ooo oOO
O
E
~ 3 1-~1 o o OO O O O O O o ~ O O O O O O O O O O
~~ ~1
_tn
,~
r~r~
20 C~)~ 31~ ~ o r~o ~D r~1 o Ln o r.\l o O ~ O n o o ~ Ln o o
~1~: r~
r51~ 3 ~n o o 1-- r.~ t U~ r ~ ~ O O O O O n O o Ln r o
E~r~1 m U ~ r~
v~
~ rL)
u 3 U~ r\l o o o o o ~ o o o u~ r~ o o o u~ o o r. o o
tn
tn
r~i)
C) '~ :1
30,~ ~, c ~ ~ r r a~ r ~D
a~
tn
r_ r r~ o ~ r.~ r~
88
- ~ 6 ~
J ~_ -
L ~ ~ , G
-
O C
-- C) U`, ~, U~ U') O U) ~, O ~ U~ O O O
V ~ ~ ~ z c~ ~~ Z
` -I
r I O O O O O O O O O O O _ O O
~ ~ O
~; ~ U~
0 3. O O O O O O O O ~v a)
C~ ~ 3
v 51 C ~ ~ Q,
r:
5 v
_ c ~ ~ C o o o o o o o o o o o o o o o
~ ~ r- u~ 3 o
20 ~ ~ C I E o o o 1-- ~ o o ~ u~ o o o o o o ~ h
o ~ ~
~ ~ c
C I v o ~ ~ o o ~D O O \D U~ In Lr) Ln co ~ ~ ~ ,1 C
~ ml ~ ~ ~ . ~ r ~ ~ o
25 0 ~v
~ o ~r o o Ln _, o o o o o o o o s
u~ ,~
3~: o,~s~ cr~ o o~ o o n
~ ~ 0
v
u~
E ~ ~D ~ 00 c ~ s
3~;
27-
1 As can be seen frorri the results of the
tests, only two samples, Nos. ~ and 19, con~aining
calcium stearate passed the UL FP-l flame retardancy
test. Tnis performance is not consiaered satisfactory.
Al.hough the two materials passed the tes~, their simi~
la-it~ in formulation to other materials indicates
rep-oducible passage of the FR-l Test would be ver~
?oor and not acceptable for commercial u'ilization.
Further samples were prepared u'ilizing a
dual component lubricant in combination ~ith the halo-
qenated flame-retardant and antimony trio~:ide as shown
in Table III.
~0
3o
.
38
--28--
U~
O O O r I n o r; rJ r~ r o
_ _ _ o o ~r
u~
r O oo ~~ O O o o ~J r r~ O
_ _ o o ~
c: o oo rJ rJ o o ~n o r~ r r~ o
r ~ r~ o r~
_ o o ~r
r~ o OO ~~ O o u~ o r~ r r~ o
rJ ~ r~ o rr~
-~ o o ~r
r~ O O O t~ N O ~ O O t~l l_ ~ _
o ~r
r~ ¦ o O ~ r~ O O O O ~1 r N U~
o o ~
r~ ¦ O ._~ r r~ O o tn O r~ r ~ O
~ ¦ o oo r~ r~ o O n o r~ r r~ o
20 ,~ r l o o r~ _~ _ r7
r~ ¦ o oo r~ r~ o o ul o r~ I~ ~ O
N I O O r~
2 5 --¦ ~ In o r~ o o L r O r~ r. r~ o
r~ o~ o ~ ~ _ ~
o O
¦ ~ o r~ ~ o o In o r r r~ o
O o
3o
~I . ~.
_~ * ~~¢ 0 ~ n~ ~ ,~ ~ ~
O~ ~ ~ V .~ n~
u~ ~D # o-~l JJ o ~l tn 0 c h
E ~ ~ v X o E ~ o~ E
~ o u~ N
~Z2~8~
1 ~he UL FR-l test ~.as conducted on the
sam~les ~hich contained the dual lub~ican~ s~stem,
the results of ~hich are sho~.~ ir. Table IV.
~,
3o
~2~ 88
--30--
tn ~ ¦ t; ~ u~ tn
Ul,1 ;" ~1 U) _' Ui t,
r~ r~ r
L:.
O ~
JJ h C O O O U; O O C O U~ U~ ~ O O O O C O U~ tn tn
o ~ Z ~ Z Z ~J ~ C C` Z ~ ~ ~ ~ Z C` C) Q)
~ ~1
~hI OOO OOO OOO OOO OOO OOO OOO
--~ l ~ 2 ~ z ~ ~ ~ - z ~- ~ z ~ ~ ~ - ~ z z z ~ z
~n
D~ ~
3,~ o O O o n o O Z O n n n o o o o o o tn tn tn
t~ ~
h¦ ooo ooo ooo ooo ooo ooo ooo
a)
H ~: h ¦ '
~ a~ uJ
f~ ~
~ h ¦ r~ o ~ ~D O O O O O O O O O ~D O o O O O O O
a
h ¦~ ~ r o ~) o ~D r~l Ln ~ ~ CO ~ ~ ~''~ U~ cn
~ ~Sl t
o
h U~
~n ooo ooo ooo ooo ooo ooo ooo
~n
~n
Q)
o a~ o
~v ~ ~ -~
s
E~
c~
tn Q o ~ ~ r~
~ E~ ~ J ~ N ~
--31--
U~ ~ ¦ Ul U~
r3 r ~-;
o ~
c ~ o o o c ~ c u ~7 ~; t,7 7 U
G` -
O O O O O O '` O O _ O O
U~
0 3.,~ O O O O O O t.7 U~ t,7 7 ~,7 U
~ 1~
r h ¦ o o o o c:~ o o O o o o C
15 ~ ~ m ~
o ~ ooo ooo ooo ooo
20 '; r~ m l~
a
m I t7 O N U~ r ~ ~ o o
o
~J hl~
Uml ooo ooo ooo ooo
a)
30 ~ ~ o r- o a~
a) E N N ~ O
u~
-32-
1 It can be seen ~rom tnese ~esults that even
under the strin~ent FR-l test, the sam?leci having
composi.tions which include the cual lubrican' system
pass ove~ 50' of the _ime wherea_ the sæmples ~.ithout
the dual lubricant svster, passec only 18' o- the time.
~ loreover, sam?les 22-30 which inciude the
dual lubricant composition, ~hen co-.pzred to sample
18 and 19 of which contain calcium stearate as a
lubricant, can be seen to retain o'her desirable
characteristics such as physical strength and elongation
capabilities as shown in Table ~'.
3~
o o o o
,,,, I ~rJ ~ -'
o ~ N
'`'I ~` ~
a~ o o o o
r~ O ~
O O O O
1~ O~ ~ O _~
O O O O
~D U~
(~ _~
O O O O
U~ r~ O N ~r
N r~J
o o o o
N ~ O ~D 11
N ~1
O O O O
~:1 N ~ ~ O ~
20 ~ .~1 ~
~ o o o o
N ~ N ~
O O O O
25 o`~
o o o o
a~ co ~ o _~
~ N
.,~ ~n
o. _~
C d~ Q ~ C
35 z ~ `3 ~ u~ o
~ l ~ ~ ,,
1~ t: o m c
u~ E~
