Note: Descriptions are shown in the official language in which they were submitted.
1~3361~1
METHOD OF MELT PROCESSING AND ARTICLE MODE OF A
STABILIZED COPOLYMER OF VINYL CHLORIDE AND
CHLOROTRIFLUOROETHYLENE
.
background OF THE INVENTION
The present invention is in the field of melt
processing polymers and articles made therefrom; in
particular, the present invention is directed to a
method of melt processing a stabilized copolymer of
vinyl chloride and chlorotrifluoroethylene and an
article made from such a composition.
In order to melt process polyvinyl chloride, it is
necessary to add plasticizers and stabilizers.
Unplasticized polyvinyl chloride is generally described
as a rigid compound. In order tumult process polyvinyl
chloride, a plasticizer is normally required. Polyvinyl
chloride is described as being relatively unstable to
heat and light. Stabilizers are typically added to
improve the heat and light stability of the polymer.
Typical stabilizers include the metallic salts of lead,
barium, tin, or cadmium. Oxides, hydroxides, or fatty
acid salts are most effective Reference is made to
FEW. Balmier, Jr., Textbook of Polymer Science, second
edition, John Wiley & Sons, Inc. (1971) at pages 419
through 422.
Copolymers of vinyl chloride, and chlorotrifluoro-
ethylene and processes to form the copolymers are
described in a variety of publications and patents. A
typical process and publication is Japanese okay 74
60,391 which discloses copolymers of vinyl chloride and
chlorotrifluoroethylene containing from 30 to 80 percent
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vinyl chloride and 20 to 70 percent chlorotrifluoro-
ethylene. The results of studies of polymers of vinyl
chloride and chlorotrifluoroethylene are disclosed in J.
Ulbricht and K. Reseller, Synthesis of Copolymers of
Vinyl Chloride and Trifluorochloroethylene, Plate Undo
Kautschuk 22 (5), 390-393 (1975); and J. Ulbricht,
Characterization and Properties of the Copolymers of
Vinyl Chloride and Trifluoroethylene, Plate Undo
Kautschuk 23 (7), 487-490 (1976). These references
-I 10 disclose copolymers containing a wide variation of
chlorotrifluoroethylene monomer and a copolymer of vinyl
chloride and chlorotrifluoroethylene. In the Ulbricht
article dated 1976 at page 4 it is noted that the heat
stability of the vinyl chloride increases with the
amount of chlorotrifluoroethylene incorporated into the
copolymer. It is disclosed that the fusibility of the
copolymer improves with the addition of chlorotrifluoro-
ethylene.
SIJMMARY OF THE INVENTION
The present invention is a method comprising the
step of melt processing a composition comprising a
copolymer comprising from 70 to 95, and preferably 75 to
90 percent by weight of vinyl chloride and from 5 to 30
and preferably 10 to 25 percent by weight of chlorotri-
fluoroethylene and an effective amount of a
- stabilizer. Preferred stabilizes include organo-metal
metallic stabilizers where the metal is selected from
the group consisting of Cadmium, zinc, barium, calcium
and mixtures thereof. The organic compound is
preferably, an oxide, hydroxide, or fatty acid salt.
Preferably, the step of melt processing is extrude
processing or roll mill processing. A particularly
preferred melt processing step is melt coating the
copolymer onto a substrate such as a wire. The present
invention includes a wire melt coated with the above-
described copolymer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is a method comprising the
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step of melt processing, a stabilized copolymer
comprising from 70 to 95 and preferably 75 to 90 percent
by weight of vinyl chloride and from 5 to 30 and
preferably 10 to 25 percent by weight of chlorotri-
fluoroethylene. The preferred embodiments of multiprocessing are extrude processing, roll mill processing
and melt coating the copolymer onto a substrate.
As indicated in the Background of the Invention, in
order to melt process polyvinyl chloride, it is
10 necessary to add plasticizer to the polyvinyl
chloride. The addition of plasticizer presents several
disadvantages. Included in these disadvantages are the
fact that plasticizers are often volatile or at least
diffuse to the surface of the polymer. A particular
disadvantage is that the plasticizers are typically
organic base compounds which reduce the fire resistance
of the polymer composition and result in large amounts
of smoke when the plasticized polyvinyl chloride
burns. Unplasticized polyvinyl chloride does not melt
drip burn, but rather chars when it burns.
Polychlorotrifluoroethylene is a melt process able
compound which is extremely flame resistant. However,
it is known to melt drip when it burns. A copolymer
having 40 percent by weight of vinyl chloride and 60
percent by weight of chlorotrifluoroethylene melt drips
- when it burns.
It has been found that a stabilized copolymer which
is from 70 to 95 percent by weight of vinyl chloride and
5 to 30 percent by weight chlorotrifluoroethylene is
useful in a method of melt processing. The stabilized
copolymer requires no plasticizer, of the type required
by polyvinyl chloride, to be melt process able. The
copolymer has flame retardant properties such that it
chars when it burns rather than melt drips A preferred
copolymer comprises from 75 to 90 percent by weight of
vinyl chloride and from 10 to 25 percent by weight of
chlorotrifluoroethylene. The copolymer can contain up
to 10 percent of other monomers so long as the
joy
terpolymer formed chars upon burning. Such other
monomers can include tetrafluoroethylene, vinylidene
fluoride, hexafluoroisobutylene, FOP and fluorinated
vinyl monomers such as those disclosed in U.S. Pat. Nos.
4,123,602 and 3,~24,250
The copolymer of vinyl chloride and sheller-
trifluoroethylene useful in the method of the present
invention can be made by methods known to copolymerize
vinyl chloride and chlorotrifluoroethylene which are
known in the art. The preferred method is that
disclosed in U.S. Serial No. 474,371, filed March 11,
1983, now U. S. Patent 4,515,927. Briefly,
vinyl chloride monomer and chlorotrifluoroethylene
monomer can be copolymerized in suspension using
procedures applicable to the the homopolymerization
vinyl chloride and suspension and well known to those
skilled in the art. According to the preferred method,
a copolymer having a constant rate ratio of vinyl
chloride to chlorotrifluoroethylene is formed in a
reactor. The suspension copolymerization is conducted
by adding an initial charge having an excess of vinyl
chloride to form a copolymer having a constant weight
ratio of vinyl chloride to chlorotrifluoroethylene. The
2 chlorotrifluoroethylene and an excess of weight of vinyl
chloride are added to water. A catalyst is added which
causes the copolymerization to take place. The
catalysts which can be used are those which are useful
in the suspension polymerization of vinyl chloride. The
reactor is preferably held at from C to 70C. The
vinyl chloride and chlorotrifluoroethylene copolymerize
to form a copolymer having a constant weight ratio of
vinyl chloride to chlorotrifluoroethylene changes.
The copolymer used in the process of the present
invention can be stabilized with an effective amount of
stabilizers useful to stabilize polyvinyl chloride.
Such stabilizers include those referenced in the
Background of the Invention as well as those listed in
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Modern Plastics Encyclopedia 1979-1980 Vol. 56, No. loan
pages 696 through 710.
Preferred stabilizes include organo-metal
metallic stabilizers where the metal is selected from
the group consisting of Cadmium, zinc, barium, calcium
and mixtures thereof. The organic compound is
preferably, an oxide, hydroxide, or fatty acid salt.
The stabilized copolymer is melt process according
to the method of the present invention. In accordance
with the present invention, the copolymer is heated to
above its melting temperature. Preferably, it is heated
to from 170C to 230C, and more preferably from 190C
to 200C.
The step of melt processing can be any useful
method of melt processing thermoplastic materials.
Typical melt processes which can be used in accordance
with the method of the present invention are disclosed
in Modern Plastics Encyclopedia 1973-80, Vol. 56, No.
loan pages 247, 248, 265, 308, 332 and 381.
2 These include extrusion
coating and laminating, compression molding, extrusion,
lamination to form film, rotational molding and other
types of molding such as injection molding. Preferred
embodiments of melt processing include extrude
processing, roll mill processing, and melt coating
preferably by extrusion coating, and laminating. A
particularly preferred use of the process of the present
invention is melt coating the copolymer onto a
substrate, such as a wire.
The present invention is useful to form a coated
substrate, preferably a coated wire comprising a wire,
and a melt coating on the wire. The melt coating
comprises the stabilized copolymer as noted above which
contains 70 to 95 percent by weight by vinyl chloride
and 5 to 35 percent by weight of chlorotrifluoroethy-
tone. The wire can be any wire known in the art which
can be coated according to the process of the present
invention. Typically, the wires are made of copper,
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aluminum, steel, and associated alloys. The wires can
be of any thickness which can be coated. The wires can
be primary wires or a coating jacket such as a plenum
jacket covering a bundle of primary wires. The coating
is applied by suitable melt coating technique. A
preferred coating method is using an extrude to melt
the copolymer and coat the wire with a cross-head die.
The thickness of the coating on the wire can be as thick
as can be made by known wire coating methods.
10 Typically, primary wire is coated to a thickness of from
4-15 miss and preferably 7 to 10 miss, and plenum jacket
coating thickness can range from 10 to 40 miss.
Several examples are set forth below to illustrate
the nature of the invention and the manner of carrying
it out. However, the invention should not be considered
as being limited to details thereof.
EXAMPLES
-
About 400 grams of vinyl chloride chlorotrifluoro-
ethylene copolymers was made in accordance with the
20 procedures disclosed in U.S. Serial No. 474,371, filed
March 11, 1983. The copolymer had between 15 to 20
percent by weight of chlorotrifl~oroethylene and
correspondingly between 80 and 85 percent of vinyl
chloride.
COY PARATIVE 1
- The above copolymer was heated to 195C. The
copolymer discolored immediately and became dark black
char after 10 minutes.
EXAMPLE 1
One hundred grams of the above copolymer was
combined with 1.5 grams of Veiniest HA vinyl stabilizer
which is believed to be a barrium/cadmium soap and one
gram of calcium Stewart. This composition was extruded
into a rod form by a plunger extrude at 195C. The
composition was extrudable but had poor thermos
stability. The composition darkened in color during the
extrusion process.
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EXAMPLE 2
Three hundred grams of a composition comprising 100
parts by weight of the above-recited copolymer 2.5 parts
by weight of the HA stabilizer, 1.0 parts by weight of
calcium Stewart, and additionally 1.5 parts by weight
of Mark 5050 pentaerythrityl/phosphite stabilizer was
added and 1.0 parts of Drape 10.4 epoxy plasticizer
was also used. Drape 10.4 although called an epoxy
plasticizer is used as a stabilizer in the composition
of this Example. Argus Product Data Sheet 12/79-10.4,
Drape 10.4 describes
Drape 10.4 epoxy plasticizer as, "designed specifically
to provide non-toxic compounds with optimum heat
stabilizing action . . . ." This composition was
extruded through a Hake one inch single screw extrude
having an L/Dra~io of 24. The extrude was operated at
Zone 1-160C, Zone 2-170C, Zone 3-180C and die at
190C. The extrude was operated at 15 to 25 rum. The
extradite appeared to have good neological properties
although it had some degradation including bubbles and
poor color.
COMPARATIVE_
Example 2 was repeated using Firestone Corp. FC-461
vinyl chloride/chlorotrifluoroethylene copolymer
containing 40 percent by weight vinyl chloride and 60
percent by weight chlorotrifluoroethylene. The
extrusion conditions were the same but the extrude was
run as 50 to 60 rum. The extradite had slight
degradation and bubbles but appeared to have good
theological properties.
The copolymer from Example 2 and Comparative 2 were
tested in accordance with the Limiting Oxygen Index
test, ASTM standard D-28~3-77. This method provides for
measuring of the minimum concentrations of oxygen and a
flowing mixture of oxygen and nitrogen that will support
flaming combustion of plastics. The measurement used is
the minimum concentration of oxygen, expressed as a
volume percent, and a mixture of oxygen and nitrogen
I,
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that will just support combustion of a material
initially at room temperature. The minimum
concentration of oxygen and the mixture of oxygen and
nitrogen flowing up within a test column that will just
support combustion is measured under equilibrium
conditions of candle-like burning. The equilibrium is
established by the relation between the heat generated
from the combustion of the specimen and the heat loss to
the surroundings is measured by one or the other to
- 10 artibrary criteria, namely a time of burning of a length
of burning of the specimen burned. This point is
approached from both sides of the critical oxygen
concentration in order to establish the oxygen index.
The copolymer used in Example 2 was found to have a
limiting oxygen index of 54. It burned with low smoke
and charred rather than dripped. One hundred percent of
vinyl chloride has a limiting oxygen between 37 and
39. It chars upon burning. The copolymer of
Comparative 2 has a limiting oxygen index of about 100
- 20 and melt drips upon burning. It is noted that when
polyvinyl chloride uses a plasticizer, it smokes while
it burns.
While exemplary embodiments of the' invention have
been described, the true scope of the invention is to be
determined from the following claims:
