Molecular sieve abstract
The disclosure of this application is directed to a composition
based on an alkylene-alkyl acrylate copolymer, a polyhydric alcohol
and an organio titanate, the cure rate of which can be retarded
by the addition thereto of a molecular sieve. The composition disclosed
can be extruded about wire and cables providing protective coatings
thereon.
Molecular sieve claims
What is claimed is:
1. A crosslinkable composition comprising an alkylene-alkyl acrylate
copolymer, a primary, polyhydric alcohol wherein primary hydroxyl
groups are attached to non-adjacent carbon atoms in an amount sufficient
to crosslink said copolymer, an organo titanate in an amount sufficient
to catalyze the crosslinking reaction between the primary, polyhydric
alcohol and the alkylene-alkyl acrylate copolymer and a molecular
sieve in an amount sufficient to retard the crosslinking reaction.
2. A crosslinkable composition comprising an alkylene-alkyl acrylate
copolymer, a primary, polyhydric alcohol wherein primary hydroxyl
groups are attached to non-adjacent carbon atoms in an amount of
about 0.1 to about 10 percent by weight, an organo titanate in an
amount of about 0.1 to about 10 percent by weight and a molecular
sieve in an amount of about 0.1 to about 5 percent by weight, wherein
amounts are based on the weight of said copolymer.
3. A composition as defined in claim 1 wherein the molecular sieves
is present in an amount of about 0.5 to about 1 percent by weight.
4. A composition as defined in claim 1 wherein the said copolymer
is an ethylene-ethyl acrylate copolymer.
5. A composition as defined in claim 1 wherein the organo titanate
is tetraisopropyl titanate.
6. A composition as defined in claim 1 wherein the polyhydric alcohol
is 14-cyclohexanedimethanol.
7. A composition as defined in claim 1 wherein the molecular sieve
has a pore size of 3A.
8. A composition as defined in claim 1 wherein the molecular sieve
has a pore size of 4A.
9. A composition as defined in claim 1 wherein the molecular sieve
has a pore size of 5A.
10. A composition as defined in claim 1 wherein the molecular sieve
has a pore size of 10A.
11. A composition as defined in claim 1 wherein the organo titanate
has the formula:
wherein each R.sup.2 is hydrogen or a monovalent hydrocarbon radical
having 1 to 18 carbon atoms provided that at least one R.sup.2 is
a monovalent hydrocarbon radical.
12. The crosslinked product of the composition defined in claim
1.
13. An electrical wire or cable having as a protective coating
thereon the composition or the cured product of the composition
defined in claim 1.
14. A process of retarding the crosslinking of a composition containing
an alkylene-alkyl acrylate copolymer, a primary, polyhydric alcohol
and an organo titanate which comprises adding thereto a molecular
sieve in an amount of about 0.1 to about 5 percent by weight based
on the weight of the said alkylene-alkyl acrylate copolymer.
15. A process as defined in claim 14 wherein the molecular sieve
is added in an amount of about 0.5 to about 1 percent by weight.
16. A crosslinkable coposition comprising an alkylene-alkyl acrylate
copolymer, a crosslinking polyol, in an amount sufficient to crosslink
said copolymer, an organo titanate in an amount sufficient to catalyze
the crosslinking reaction between said polyol and said copolymer
and a molecular sieve in an amount sufficient to retard the crosslinking
reaction.
17. An additive, suitable for crosslinking an alkylene-alkyl acrylate
copolymer at elevated temperatures, comprising a polyol capable
of crosslinking an alkylene-alkyl acrylate copolymer, an organo
titanate catalyst and a molecular sieve.
18. An additive as defined in claim 17 wherein the polyol is 14-cyclohexanediol.
19. An additive as defined in claim 17 wherein the organo titanate
is tetraisopropyl titanate.
20. An additive as defined in claim 17 wherein the polyol is 14-cyclohexanediol
and the organo titanate is tetraisopropyl titanate.
Molecular sieve description
SUMMARY OF THE INVENTION
This application relates to compositions based on an alkylene-alkyl
acrylate copolymer, a crosslinking polyol and an organo titanate,
the cure rates of which can be retarded by the addition thereto
of a molecular sieve, allowing for extrusion of the compositions
at relatively high temperatures. The compositions of this invention
are particularly useful in extrusion applications, being capable
of extrusion at relatively high temperatures, without crosslinking
in the extruder, about electrical wires and cables and telephone
wires and cables to provide protective insulation or jacketing thereon.
BACKGROUND OF THE INVENTION
Currently, protective coatings, such as insulation and jacketing,
are being applied about electrical wires and cables by extruding
thereon compositions containing an organic peroxide and subjecting
the resultant articles to elevated temperatures in order to cure
the compositions to crosslinked products. The overall operation,
commonly referred to as peroxide curing, requires careful control
of the process parameters in order to avoid undue heat and pressure
build-up in the extruder. Undue heat and pressure build-up, results
in premature decomposition of the peroxides which in turn results
in crosslinking of the compositions in the extruder. Crosslinking
of the compositions in the extruder, commonly referred to as "scorch"
necessitates, in extreme cases, stopping the operation and cleaning
the extruder.
DESCRIPTION OF THE INVENTION
The present invention provides compositions, based on alkylene-alkyl
acrylate copolymers, which do not suffer the processing difficulties
of peroxide curing and are particularly useful as protective extrudates,
serving as insulation about electrical wires and cables and as jacketing
about telephone wires and cables.
The compositions of this invention allow for wide latitude in the
processing thereof in that the compositions can be extruded, without
scorch, at temperatures far in excess of the maximum processing
temperatures used in extruding compositions containing organic peroxides.
Being capable of extrusion at relatively high temperatures, the
compositions of the present invention can be extruded at faster
rates and consequently, at lower overall cost, yielding protective
coatings of improved surface characteristics.
The compositions of the present invention comprise an alkylene-alkyl
acrylate copolymer, a crosslinking polyol, an organo titanate and
a molecular sieve; wherein the polyol is present in an amount sufficient
to crosslink the alkylene-alkyl acrylate copolymer to a crosslinked
product, generally in an amount of about 0.1 to about 10 percent
by weight; the organic titanate is present in a catalytic amount,
sufficient to catalyze the crosslinking reaction between the alkylene-alkyl
acrylate copolymer and the polyol, generally in an amount of about
0.1 to about 10 percent by weight; and the molecular sieve is present
in an amount sufficient to retard the crosslinking reaction, generally
in an amount of about 0.1 to about 5 percent by weight, preferably
about 0.5 to about 1 percent by weight.
Amount by weight, unless otherwise noted, is based on the weight
of the alkylene-alkyl acrylate copolymer.
The alkylene-alkyl acrylate copolymers are known copolymers produced
by reacting an alkene with an alkyl acrylate. The term "acrylate"
is intended to encompass acrylates as well as methacrylates, as
set forth below.
Suitable alkenes are ethylene, propylene, butene-1 isobutylene,
pentene-12-methylbutene-13-methylbutene-1 hexene-1 heptene-1
octene-1 and the like and mixtures thereof.
The alkylene moiety of the alkylene-alkyl acrylate copolymer generally
contains from 2 to 18 carbon atoms inclusive, preferably 2 to 3
carbon atoms inclusive.
Suitable alkyl acrylate monomers which are copolymerized with the
alkenes fall within the scope of the following formula: ##STR1##
wherein R.sub.1 is hydrogen or methyl and R.sub.2 is alkyl having
one to 8 carbon atoms. Illustrative compounds encompassed by this
formula are: methyl acrylate, ethyl acrylate, t-butyl acrylate,
methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl
acrylate and the like and mixtures thereof.
Alkylene-alkyl acrylate copolymers generally have a density (ASTMD-1505
with a conditioning as in ASTMD-147-72) of about 0.92 to about 0.94
and a melt index (ASTMD-1238 at 44 psi tested pressure) of about
0.5 to about 500 decigrams per minute.
For purposes of the present invention, the preferred copolymer
generally has about one to about 50 percent by weight combined alkyl
acrylate, preferably about 5 to about 20 percent by weight combined
alkyl acrylate.
Crosslinking polyols, for purposes of the present invention, are
compounds having at least two primary hydroxyl groups attached to
non-adjacent carbon atoms.
Illustrative of such polyols are the polyhydric alcohols such as
the dihydric alcohols having the formula: ##STR2## wherein the sum
of m+p is at least 2 preferably 2 to 20 inclusive and R.sup.1 and
R.sup.2 which can be the same or different, are hydrogen or alkyl
and when alkyl, containing 1 to 20 carbon atoms inclusive. Specific
compounds include, among others, propylene glycol, butanediol-14
hexanediol-16 decanediol-110 neopentyl glycol and the like.
Also suitable are the ether diols having the general formula: ##STR3##
wherein a has a value of at least 1 preferably 2 to 20 inclusive,
and x has a value of at least 2 preferably 2 to 10 inclusive. Among
compounds falling within the scope of this formula are di(ethylene
glycol), di(propylene glycol) including the commercially available
poly(ethylene glycol) and poly(propylene glycol).
Other suitable polyols are the cycloaliphatic polyhydric alcohols
such as cyclohexanedimethanol and the like, trihydric alcohols such
as glycerol and the like, the tetrahydric alcohols such as pentaerythritol
and other polyols which are described in U.S. application Ser. No.
106502 filed Dec. 26 1979 now U.S. Pat. No. 4351926 granted
Sept. 28 1982 in the name of Michael J. Koegh and assigned to a
common assignee, Union Carbide Corporation, the disclosure of which
is incorporated herein by reference.
Suitable organo titanate compounds are characterized by the following
formula:
wherein each R.sup.2 which can be the same or different, is hydrogen
or a monovalent hydrocarbon radical having one to 18 carbon atoms,
preferably one to 14 carbon atoms, provided at least one R.sup.2
is a monovalent hydrocarbon radical.
Exemplary of suitable hydrocarbon radicals are alkyl radicals such
as methyl, ethyl, n-propyl, isopropyl, butyl, octyl, lauryl, myristyl,
stearyl and the like; cycloaliphatic radicals such as cyclopentyl,
cyclohexyl and the like; aryl radicals such as phenyl, methylphenyl,
chlorophenyl and the like; alkaryl radicals such as benzyl and the
like.
Organo titanates falling within the scope of Formula IV are known
compounds and can be conveniently prepared as described in U.S.
Pat. No. 2984641 to Leon E. Wolinsky patented May 16 1961.
Other suitable organo titanates are the organo titanium chelates
such as tetraoctylene glycol titanium, triethanol amine titanate,
titanium acetyl acetonate, titanium lactate and the like.
Molecular sieves which serve to retard the crosslinking reaction,
as previously explained, allowing for extrusion of the compositions
at higher temperatures, are well known materials. These molecular
sieves or crystalline zeolites are alumina-silica materials of the
general formula:
To the compositions of this invention may be added various additives,
in amounts well known in the art, such as fillers among which can
be mentioned carbon black, clay, talc, magnesium silicate, calcium
carbonate, silica, aluminum hydroxide and the like, antioxidants
such as 12-dihydro-234-trimethylquinoline and the like.
The compositions can be rendered flame retardant by the addition
thereto of halogen containing flame retardants such as decabromodiphenyloxide,
chlorinated polyethylene, polyvinyl chloride and halogenated paraffin
waxes, along, or in admixture with organic or inorganic antimony
compounds such as antimony oxide and/or alkaline earth metal oxides,
carbonates, hydroxides and sulfates. Among such alkaline earth metal
compounds can be noted calcium oxide, calcium carbonate, calcium
hydroxide, calcium sulfate, magnesium oxide, magnesium carbonate,
magnesium hydroxide and magnesium sulfate.
It is to be noted that mixtures of reactants, catalysts, sieves
and the like can be used if so desired.
Formulation of the compositions of this invention can be carried
out by mixing the components thereof in a suitable mixer such as
a Brabender mixer, at elevated temperatures on the order of about
100.degree. C. to about 130.degree. C. until a blend is obtained.
A suitable procedure is described in reference to the examples which
follow. These examples are illustrative of the present invention
and are not intended to limit the scope thereof in any manner.
The curing or crosslinking of the compositions is effected by heating
the compositions at elevated temperatures on the order of about
380.degree. F. to about 800.degree. F., preferably temperatures
on the order of about 450.degree. F. to about 600.degree. F.
Actually, it is preferred to carry out the crosslinking as the
last step in the overall extrusion operation wherein the composition
is extruded about a wire or cable and the extruded product, once
out of the extruder is subjected to the temperatures previously
noted while in an inert gas atmosphere.
In order to demonstrate the desirable characteristics of the compositions
of this invention, a number of compositions, formulated as described
below, were prepared, formed into plaques and subjected to the Monsanto
Rheometer test.
The Monsanto Rheometer test is fully described in U.S. Pat. No.
4017852 granted Apr. 19 1977 the disclosure of which is incorporated
herein by reference. Briefly, FIG. 1 of this patent shows the typical
Monsanto Rheometer curve. The cure level (highest crosslink density)
is designated as H. It is measured in terms of inch-pounds or torque
on the Rheometer test equipment. A higher value for H corresponds
to a higher crosslink density.
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