[0001] This invention relates to an electrically insulating polymer composition and a wire
or a cable using such a composition. More particularly, the present invention relates
to a composition that provides an excellent electrical insulator in terms of volume
resistivity, breakdown strength and other electrical properties. It also relates to
a polymer composition for providing an excellent electrical insulator that does not
degrade in terms of volume resistivity, breakdown strength and other electrical properties
as well as to a wire, a cable or a DC power cable comprising an electrically insulating
polymer composition or an insulation layer formed by such a composition or a material
obtained by crosslinking such a composition.
2. Background Art
[0002] Insulating materials for wires or cables are, by definition, required to show a high
volume resistivity, a high breakdown strength, a low dielectrical constant and a low
loss tangent and typically made of polyethylene. While oil-fill insulators (hereinafter
referred to as OFs) are used for large capacity power supply cables and provide satisfactory
electrical insulation, the OF is accompanied by certain draw-backs including that
it should be constantly supplied with oil to offset the quantity of oil that leaks
out of it. In recent years, crosslinked olefinic polymers such as crosslinked polyethylene
are getting popularity as they show an enhanced level of thermal resistance and physical
strength.
[0003] Techniques for crosslinking include electron beam induced crosslinking and chemical
crosslinking using peroxides and the like, of which the former requires large equipment
and hence costly. While chemical crosslinking is less costly, crosslinking agents
can remain in the products and gradually reduce the volume resistivity of the products
, and give rise to water trees and other problems.
[0004] In an attempt to improve the electrical insulation of insulating materials and eliminate
the problem of water trees, Japanese Patent Publication No. 5-15007 proposes a method
of introducing polyolefin that is modified with maleic anhydride into polyethylene
for the purpose of introducing hydrophilic groups. Japanese Patent Laid-open Publication
No. 4-11646 discloses a method of improving the electrical insulation of an insulating
material by introducing double bonds in advance into polyolefin to be crosslinked
and thereby reducing the rate of the use of crosslinking agent. However, neither of
these methods operates satisfactorily for the improvement of volume resistivity and
other aspects of electrical insulation and thermal resistance.
[0005] The inventors of the present invention had found sometime ago that electrically highly
insulating materials can be produced by using maleic anhydride at a very limited rate.
While these materials surpass normally crosslinked polyolefinic materials by far for
electrical insulation, they are still not satisfactory in terms of volume resistivity
and other properties of electrical insulation.
[0006] Meanwhile, methods have been proposed concerning the use of carboxylic compounds
and/or aromatic compounds with polyolefin in order to improve the electrical insulation
of the final product. Examples of such proposed methods include the use of polystyrene
grafted to polyolefin in order to improve the impulse breakdown strength of the final
product (Japanese Patent Publication No. 2-165506), the use of a blend of polyethylene
and polystyrene also in order to improve the impulse breakdown strength of the final
product (Japanese Patent Laid-open Publication No. 63-301427), the use of a blend
of polyolefin and polystyrene modified with maleic anhydride in order-to improve the
electrical insulation of the final product (Japanese Patent Laid-open Publication
No. 62-100909) and the use of a blend of polyolefin and aromatic carboxylic acid in
order to improve the breakdown strength of the final insulating product (Japanese
Patent Laid-open Publication No. 60-23904).
[0007] A polymer composition having improved insulating properties is further described
in EP-A-0 463 402. This composition comprises an ethylene (co)polymer containing polar
groups having a dipole moment of more than 0.8 debye which may be selected from ketone
groups, nitrile groups and nitro groups. A specific example of such copolymer is an
ethylene-acrylonitrile copolymer.
[0008] However, any of these methods cannot satisfactorily improve an insulating material
of the type under consideration in terms of both the volume resistivity and the breakdown
strength. They are not satisfactory either in terms of improvement in the electrical
insulation of the material after crosslinking.
[0009] It is therefore an object of the present invention to provide a polymer composition
that operates as an excellent electrical insulator in terms of volume resistivity,
breakdown strength and other electrical properties. It is also an object of the invention
to provide a composition capable of being crosslinked to a large extent that operates
as an excellent electrical insulator that does not degrade after crosslinking in terms
of volume resistivity, breakdown strength and other electrical properties as well
as to a wire, a cable or a DC power cable having an insulation layer formed by such
a composition or a material obtained by crosslinking such a composition.
SUMMARY OF THE INVENTION
[0010] As a result of intensive research efforts, the inventors of the present invention
achieved the present invention.
[0011] According to an aspect of the invention, the above objects are achieved by providing
an electrically insulating polymer composition comprising an olefinic polymer and
at least one type of
functional group containing monomer units selected from monomer units derived from
monomers D1 through D3 at a rate of 5x10
-7 to 5x10
-3 mols per gram of the composition, and also comprising ethylenic linkages at a rate
of not smaller than 0.8 per 1,000 carbon atoms and/or aromatic ring containing monomer
units derived from monomer D4 at a rate of 5x10
-7 to 5x10
-3 mols per gram of the composition, wherein said monomers D1 through D4 have an ethylenic
linkage, said monomer D1 is a carbonyl group or carbonyl group derivative containing
monomer, said monomer D2 is a hydroxyl group containing monomer, said monomer D3 is
a nitrile group containing monomer, and said monomer D4 is an aromatic ring containing
monomer.
[0012] According to a second aspect of the invention, there is provided a wire or a cable
having an electrically insulating polymer composition as defined above or an insulating
layer made of such a composition or a material obtained by crosslinking such a composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
Figures 1(a) and (b) are schematic illustrations of an electrode system used for testing
the volume resistivity of specimens of a composition according to the present invention,
wherein Fig. 1(a) is a plan view of the electrode system and Fig. 1(b) is a sectional
view thereof.
Figure 2 is a schematic illustration of an electrode system used for testing the breakdown
strength of specimens of a composition according to the present invention.
Figure 3 is a schematic illustration of an water tree observing system used for testing
specimens of a composition according to the present invention.
Figure. 4 is a graph showing the performances of Examples 1 through 6 according to
the present invention and those of Comparative Examples 1, 4 and 5, expressed in terms
of the relationship between the functional group concentration (horizontal axis) and
the volume resistivity (vertical axis).
Figure 5 is a graph showing the performances of Examples 7 through 10 according to
the present invention and 13 through 15 and those of Comparative Examples 1, 4, 5
and 10.
Figure 6 is a schematic cross sectional view of a cable according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Now, the invention will be described in greater detail.
[0015] For the purpose of the above first aspect of the invention and for introducing said
functional group containing monomers and said ethylenic linkages into said composition,
said electrically insulating polymer composition preferably comprises a polymer having
said functional group containing monomers D1 through D3, a polymer having monomeric
units containing two or more ethylenic linkages and/or a copolymer having said aromatic
ring containing monomer D4.
[0016] Particularly, for the purpose of the above first aspect of the invention, said composition
may preferably comprises at least one of component (A), component (B) and component
(C) as defined below;
component (A): at least one of (A1) and (A2) below;
- (A1):
- an olefinic polymer, and
- (A2):
- a random copolymer of olefin and at least one of said functional group containing
monomers D1 through D4 or a graft copolymer obtained by modifying an olefinic polymer
with at least one of said functional group containing monomers D1 through D4,
component (B): at least one of (B1) through (B3) below;
- (B1):
- a homopolymer derived from a monomer containing two or more ethylenic linkages or
a copolymer of said monomer and ethylene,
- (B2):
- a random copolymer of a monomer containing two or more ethylenic linkages and at least
one of said functional group containing monomers D1 through D4, a random copolymer
of a monomer containing two or more ethylenic linkages, ethylene and at least one
of said functional group containing monomers D1 through D4 or a graft copolymer obtained
by modifying a homopolymer derived from a monomer containing two or more ethylenic
linkages or a copolymer of said monomer and ethylene with at least one of said functional
group containing monomers D1 through D4, and
- (B3):
- a compound containing two or more ethylenic linkages,
component (C): at least one of (C1) and (C2) below;
- (C1):
- an olefinic polymer containing at least one aromatic ring, and
- (C2):
- a random copolymer of olefin, at least one of said functional group containing monomers
D1 through D3, and said aromatic ring containing monomer D4 or a graft copolymer obtained
by modifying an olefinic polymer containing aromatic rings with at least one of said
functional group containing monomers D1 through D3, or a graft copolymer obtained
by modifying a random copolymer of olefin and at least one of said functional group
containing monomers D1 through D3 with said aromatic ring containing monomer D4.
[0017] For the purpose of the present invention, said olefinic polymer of the component
(A1) is a homopolymer or copolymer of hydrocarbons expressed by general formula C
nH
2n which can be selected from ethylene, propylene, 1-butene, 2-butene, isobutylene,
1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 1-hexene,
2,3-dimethyl-2-butene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene
and so on.
[0018] Examples of the olefinic polymers that can be used for the purpose of the present
invention include high, medium or low density polyethylene, linear low density polyethylene,
very low density polyethylene, polypropylene, polybutene, polypentene, poly-4-methyl-1-pentene,
ethylene-α-olefin copolymer, ethylene-propylene copolymeric rubber (EPR), low density
polyethylene obtained by a high pressure radical method and ethylene copolymer obtained
by a high pressure radical method. Of these olefinic polymers, low density polyethylene
obtained by a high pressure radical method, high, medium or low density polyethylene,
linear low density polyethylene and polypropylene are preferable.
[0019] For the purpose of the present invention, a functional group containing monomers
having an ethylenic linkage may be the monomer D1: carbonyl group or carbonyl group
derivative containing monomer, the monomer D2: hydroxyl group containing monomer,
the monomer D3: nitrile group containing monomer and the monomer D4: aromatic ring
containing monomer. Specific examples of such monomers will be listed below.
[0020] Examples of the carbonyl group or carbonyl group derivative containing monomer D1
include unsaturated carboxylic acids derived from α,β-unsaturated carboxylic acids,
unsaturated carboxylates derived from α,β-unsaturated carboxylates and vinylester
monomers. Examples of unsaturated carboxylic acid include acrylic acid, methacrylic
acid, maleic acid, fumaric acid and itaconic acid. Examples of unsaturated carboxylates
include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate,
n-butyl acrylate, n-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate,
lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, methyl
maleate, ethyl maleate, dimethyl maleate, diethyl maleate, methyl fumarate, ethyl
fumarate, glycidyl acrylate and glycidyl methacrylate.
[0021] Examples of vinylester that can be used for the purpose of the present invention
include vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate, vinyl laurate,
vinyl stearate and vinyl trifulorate, of which vinyl acetate is most preferable.
[0022] Examples of acid anhydrides to be used for carbonyl group derivative containing monomers
for the purpose of the present invention include maleic anhydride, itaconic anhydride,
methylmaleic anhydride, dimethylmaleic anhydride, phenylmaleic anhydride, diphenylmaleic
anhydride, chloromaleic anhydride, dichloromaleic anhydride, fluoromaleic anhydride,
difluoromaleic anhydride, bromomaleic anhydride and dibromomaleic anhydride, of which
maleic anhydride is most preferable.
[0023] Other monomers that can be used for the purpose of the present invention include
carbon monoxide, methylvinylketone, isopropenylvinylketone, ethylvinylketone, phenylvinylketone,
t-butylvinylketone, isopropylvinylketone, methylpropenylketone, methylisopropenylketone
and cyclohexylvinylketone.
[0024] Examples of the hydroxyl group containing monomer D2 include vinylalcohol, 1-hydroxypropyl(meth)acrylate,
2-hydroxypropyl(meth)acrylate and hydroxyethyl(meth)acrylate.
[0025] Examples of the nitrile group containing monomer D3 include acrylonitrile, methacrylonitrile,
α-methoxyacrylonitrile, vinylidenecyanide, cinnamonitrile, crotononitrile, α-phenylcrotononitrile,
fumaronitrile, arylacetonitrile, 2-butenenitrile and 3-butenenitrile.
[0026] For the purpose of the present invention, the aromatic ring containing monomer D4
is a compound containing a monocyclic or polycyclic aromatic ring and having ethylenic
linkages.
[0027] Examples of said aromatic ring containing monomer D4 that can be used for the purpose
of the present invention are preferably aromatic compounds containing a monocyclic,
dicyclic or tricyclic aromatic ring and include styrene and its derivatives, arylbenzene,
arylbiphenyl, methylstyrene, aryl benzoate, vinylnaphthalene, 4-phenyl-1-butene, benzil
methacrylate, 1,1-diphenylethylene, 4-phenyl-1-tolylethylene, 1-phenyl-1-styrylethane,
1-tolyl-1-styrylethane, 2,4-diphenyl-1-butene, 2,4-diphenyl-1-pentene and 2,4-diphenyl-4-methyl-1-pentene.
[0028] Of the above examples, styrene is most preferably in terms of the electrical performance
of the final product.
[0029] The rate at which the functional group containing monomers need to be between 5x10
-7 and 5x10
-3 mols, preferably between 1x10
-6 and 1x10
-4 mols and most preferably between 1x10
-6 and 1x10
-5 mols for each one gram of polymer composition not containing any crosslinking agent.
[0030] If the concentration of the functional groups of the monomers of D1 through D3 including
maleic anhydride is less than 5x10
-7 mols per one gram of the polymer composition, the volume resistivity of the final
product would not be improved. If the same is true with the functional group of the
monomer of D4, the breakdown strength of the final product would not be improved either.
If, on the other hand, the concentration is greater than 5x10
-3 mols per one gram of polymer composition, the volume resistivity of the final product
is degraded.
[0031] Copolymers that can be used for a random copolymer of olefin and at least one of
said functional group containing monomers D1 through D4 or a graft copolymer obtained
by modifying an olefinic polymer with at least one of said functional group containing
monomers D1 through D4 as defined for the component (A2) include linear low density
polyethylene modified with acrylic acid or maleic anhydride, high, medium or low density
polyethylene modified with acrylic acid or maleic anhydride, copolymer of ethylene
and acrylic acid or maleic anhydride, copolymer of ethylene and carbon monoxide, ethylene-methylvinylketone
copolymer, ethylene-methylisopropenylketone copolymer, ethylene-hydroxyethyl(meth)acrylate
copolymer, ethylene(meth)acrylonitrile copolymer, ethylene-arylacetonitrile copolymer
and low density polyethylene modified with styrene.
[0032] A homopolymer derived from a monomer containing two or more ethylenic linkages or
a copolymer of said monomer and ethylene as defined for the component (B1) needs to
contain double bonds to a sufficient rate after polymerization. According to the existence
of the ethylenic linkages, the final product shows a satisfactory crosslinked effect.
For 5 the component (B), a liquid oligomer or copolymer having an average molecular
weight of 1,000 to 200,000 will be used.
[0033] A homopolymer derived from a monomer containing two or more ethylenic linkages as
defined in the former half of (B1) is a diene polymer having 4 to 10 carbon atoms.
The diene polymer may be cyclic or straight chain so long as it has two or more double
bonds. However, butadiene oligomer or polybutadiene having an average molecular weight
of 1,000 to 20,000 is most preferable because it is excellent in terms of electrical
insulation and crosslinking efficiency after crosslinking.
[0034] Examples of such compounds include 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene,
2-methyl-1,3-butadiene, 1,3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, 2,4-hexadiene,
2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-heptadiene, 1,4-heptadiene,
3-(2-propenyl)-cyclopentene and 2-(cyclopentyl)-1,3-butadiene. Trienes and tetraenes
that can be prepared from dienes by polymerization can also be used.
[0035] Of the above candidate compounds, monomer of 1,3-butadiene is most preferable because
of its crosslinking effect.
[0036] Compounds that can be used a random copolymer of monomer containing two or more ethylenic
linkages and ethylene as defined in the latter half of (B1) include ethylene-aryl(meth)acrylate
copolymer and ethylene-vinyl(meth)acrylate copolymer. Alternatively, a mixture of
two or more of such copolymers may be used.
[0037] Examples of a random copolymer of a monomer containing two or more ethylenic.linkages
and at least one of said functional group containing monomers D1 through D4, a random
copolymer of a monomer containing two or more ethylenic linkages, ethylene and at
least one of said functional group containing monomers D1 through D4 or a graft copolymer
obtained by modifying a homopolymer derived from a monomer containing two or more
ethylenic linkages or a copolymer of said monomer and ethylene with at least one of
said functional group containing monomers D1 through D4 as defined in (B2) include
polybutadiene modified with acrylic acid or maleic anhydride; maleic anhydride-butadiene
copolymer, maleic acid-modified ethylene-aryl(math)acrylate copolymer and maleic acid-modified
ethylene-vinyl(meth)acrylate copolymer.
[0038] Of these, polybutadiene modified with acrylic acid or maleic anhydride is most preferable.
[0039] Examples of compounds that can be used for a compound containing two or more ethylenic
linkages as defined in (B3) include methacrylate monomers having a number of functional
groups such as trimethylolpropane trimethacrylate, ethyleneglycol dimethacrylate and
diethyleneglycol dimethacrylate; vinyl monomers having a number of functional groups
such as triarylisocyanurate, diarylphthalate and vinylbutyrate; bismaleimides such
as N, N'-m-phenylenebismaleimide and N,N'-ethylenbismaleimide; dioximes such as P-quinonedioxime;
divinyl compounds such as divinylbenzene, 1,5-hexadiene-3-in, hexatriene, divinylether,
divinylsulfone; and diaryl compounds such as arylstyrene, 2,6-diacrylphenol, diarylcarbinol.
[0040] For component (B) defined as (B1), (B2) or (B3), before being crosslinked, the composition
contains at a rate not less than 0.8 double bonds per 1,000 carbon atoms. Preferably,
the number of double bonds is between 0.8 and 4.0 per 1,000 carbon atoms.
[0041] In addition, when containing the double bonds, preferably the number of terminal
vinyl group is between 0.5 and 3.0 per 1,000 carbon atoms.
[0042] An olefinic polymer containing at least one aromatic ring as defined in (C1) above
is a copolymer of a monomer containing a monocyclic or polycyclic aromatic ring and
olefin.
[0043] For the purpose of the present invention, a monomer containing at least one aromatic
ring is preferably an aromatic compound having a mono-, di- or tricyclic aromatic
ring and selected from compounds including styrene, styrene derivatives, arylbenzene,
arylbiphenyl, methylstyrene, aryl benzoate, vinylnaphthalene, 4-phenyl-1-butene, benzyl
methacrylate, 1,1-diphenylethylene, 1-phenyl-tolylethylene, 1-phenyl-l-styrylethane,
2,4-diphenyl-1-butene, 2,4-diphenyl-1-pentene and 2,4-diphenyl-4-methyl-1-pentane.
[0044] Olefines that can be used in component (C1) for the purpose of the invention include
α-olefines having 3 to 12 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene,
1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene.
[0045] Of olefinic polymers containing aromatic rings, an ethylene-styrene random copolymer
is most preferable.
[0046] A random copolymer of olefin, at least one of said functional group containing monomers
D1, and said aromatic ring containing monomer D4 or a graft copolymer obtained by
modifying an olefinic polymer containing aromatic rings with at least one of said
functional group containing monomers D1 through D3, or a graft copolymer obtained
by modifying a random copolymer of olefin and at least one of said functional group
containing monomers D1 through D3 with said aromatic ring containing monomer D4 as
defined in component (C2) above is selected from compounds including ethylene-styrene-maleic
anhydride random copolymer, maleic anhydride modified ethylene-styrene copolymer,
ethylene-arylbenzen copolymer, maleic anhydride modified ethylene-benzyl methacrylate
copolymer, and maleic anhydride modified ethylene-arylstyrene.
[0047] Examples of copolymers of at least one of monomers containing a styrene derivative
and ethylene that can be used for the purpose of the present invention include ethylene/vinylacetate/styrene
copolymer, ethylene/vinylacetate/α-methylstyrene copolymer, ethylene/ethyl acrylate/styrene
copolymer and ethylene/ethyl acrylate/α-methylstyrene copolymer.
[0048] For component (C) defined as components (C1) or (C2), the concentration of said aromatic
containing monomer in the composition is between 5x10
-7 and 5x10
-3 mols, preferably between 1x10
-6 and 1x10
-4 mols and most preferably between 1x10
-6 and 5x10
-5 mols per 1 gram of the polymer composition.
[0049] Now, some preferable combinations of candidate components of a polymer composition
according to the present invention will be described.
(1) As claimed in claim 4, a combination of an olefinic polymer (A1) as component
(A) and a graft copolymer (B21) obtained by modifying a homopolymer derived from a
monomer containing two or more ethylenic linkages or a copolymer of said monomer and
ethylene with a functional group containing monomer D1 as component (B) is provided.
An example of such a combination is obtained from unmodified low density polyethylene
(A1) obtained by high pressure radical polymerization and maleic anhydride modified
liquid polybutadiene (B21).
(2) As claimed in claim 5, a combination of an olefinic polymer (A1) and a graft copolymer
(A21) obtained by modifying an olefinic polymer with a functional group containing
monomer D1 as component (A) and a graft copolymer (B21) obtained by modifying a homopolymer
derived from a monomer containing two or more ethylenic linkages or a copolymer of
said monomer and ethylene with a functional group containing monomer D1 as component
(B) is provided. An example of such a combination is obtained from unmodified low
density polyethylene (A1) obtained by high pressure radical polymerization, maleic
anhydride modified low density polyethylene (A21) and maleic anhydride modified liquid
polybutadiene (B21).
(3) As claimed in claim 6, a combination of an olefinic polymer (A1) and a graft copolymer
(A21) obtained by modifying an olefinic polymer with a functional group containing
monomer D1 as component (A) and a compound (B3) having two or more ethylenic linkages
as component (B) is provided. An example of such a combination is obtained from unmodified
low density polyethylene (A1) obtained by high pressure radical polymerization, maleic
anhydride modified low density polyethylene (A21) and divinylbenzene (B3).
(4) As claimed in claim 7, a combination of a graft copolymer (B21) obtained by modifying
a homopolymer derived from a monomer having two or more ethylenic linkages or a copolymer
of said monomer and ethylene with a functional group containing monomer D1 as component
(B) and an olefinic polymer (C1) containing at least one aromatic ring as component
(C) is provided. An example of such a combination is obtained from maleic anhydride
modified liquid polybutadiene (B21) and ethylene-styrene random copolymer (C1).
(5) As claimed in claim 8, a combination of a graft copolymer (A21) obtained by modifying
an olefinic polymer with a functional group containing monomer D1 as component (A)
and an olefinic polymer (C1) containing at least one aromatic ring as component (C)
is provided. An example of such a combination is obtained from maleic anhydride modified
low density polyethylene (A21) and ethylene-styrene random copolymer (C1).
(6) As claimed in claim 9, a combination of an olefinic polymer (C1) containing at
least one aromatic ring and a graft copolymer (C21) obtained by modifying an olefinic
polymer with a functional group containing monomer D1 as component (C) is provided.
An example of such a combination is obtained from ethylene-styrene random copolymer
(C1) and ethylene-styrene-maleic anhydride graft copolymer (C21).
[0050] For the purpose of the present invention, while a composition according to the present
invention may well be used by itself as an electrically insulating material, it is
preferable to crosslink it in order to improve the volume resistivity and the breakdown
strength. While any appropriate crosslinking techniques including the use of a radical
generating agent such as an organic peroxide, electron beam induced crosslinking and
silane crosslinking may be used, the use of a radical generating agent is preferable
in view of cost effectiveness.
[0051] Examples of radical generating agents that can be used for the purpose of the present
invention include peroxides such as benzoylperoxide, laurylperoxide, dicumylperoxide,
t-butylhydroperoxide, α,α-bis(t-butylperoxideisopropyl)benzene, di-t-butylperoxide,
2,5-di(t-butylperoxy)hexane, 2,5-di(t-butylperoxy)hexene; azobisisobutylonitrile,
2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-di(p-methylphenyl)butane
and 2,3-diethyl-2,3-di(bromophenyl)butane.
[0052] In the crosslinking process, the volume resistivity and other electrical properties
of the composition can be improved by crosslinking the composition after preparing
a given amount of component (B).
[0053] The radical generating agents for modifying component (B) with an functional group
containing monomer as described above may mostly used as crosslinking agents for the
purpose of the present invention. Of the crosslinking agents listed above, dicumylperoxide,
2,5-di-(t-butylperoxy)hexane and 2,5-di-(t-butylperoxy)hexene are recommendable.
[0054] The crosslinking agent is used by an amount between 0.01 to 5 parts by weight, preferably
between 0.1 and 3 parts by weight, for a total of 100 parts by weight of the composition.
[0055] The composition according to the present invention may include one or more chemicals
selected from inorganic fillers, organic fillers, antioxidants, lubricants, organic
or inorganic pigments, ultraviolet preventing agents, photostabilizers, dispersing
agents, anti-copper-corrosion agents, neutralizing agents, plasticizers, and nucleating
agents.
[0056] An insulating polymer composition according to the present invention can be used
for insulating materials for wires, cables and capacitors, for the insulation of high
voltages areas of X-ray generators and cables and other applications.
[0057] A wire or a cable according to the present invention is one comprising an insulation
layer made of a polymer composition according to the present invention or a composition
obtained by crosslinking said composition.
[0058] More specifically, a wire or a cable according to the present invention is one comprising
an insulation layer covering its conductor. If necessary, a bundle of wires may be
used for the conductor and a semiconducting layer may be arranged between the conductor
and the insulation layer. A flame retarding polymer layer may be formed outside the
insulation layer.
[0059] For the purpose of the present invention, a wire or a cable may be prepared by coating
a bundle of copper wires with a polymer composition containing carbon powder or metal
powder to form semiconducting layer, forming thereon an insulation layer of a polymer
composition according to the present invention, arranging thereon a coat of metal
sheet or still another semiconducting layer and then forming an outermost coat of
a flame retarding or rat repellent polymer layer. Alternatively, a wire or a cable
may be prepared by combining several to tens of several covered copper wires, each
comprising a single copper wire coated with a semiconducting layer of a polymer composition
containing carbon or metal powder and an insulation layer of a polymer composition
according to the present invention, and forming an outermost coat of a flame retarding
or rat repellent polymer layer. A polymer composition according to the present invention
is particularly effective for high voltage and can be suitably used for DC power cables.
[Functions]
[0060] The present invention provides an electrically insulating polymer composition comprising
an olefinic polymer as a principal ingredient and a functional group containing monomer,
and also comprising ethylenic linkage and/or an aromatic ring containing monomer.
[0061] The functional group operates as a trap site that blocks the movement of electrical
charges and consequently improve the volume resistivity of the composition.
[0062] The aromatic ring has an effect of taking up highly energized electrons, causing
them to emit their energy in the form of heat and releasing them with a low energy
level (electron energy absorption effect). Thus, the energy level of highly energized
electrons that can trigger electrical breakdown can be significantly reduced to enhance
the breakdown strength of the composition.
[0063] The electrical properties of an insulating material prepared from a polymer composition
according to the present invention can be improved by crosslinking particularly in
terms of volume resistivity, the phenomenon of water tree and breakdown strength.
The double bonds in a diene polymer improves the efficiency of crosslinking since
they operates as crosslinking sites. The decomposition residues of the crosslinking
agent are taken up in the main chain of the polymer. The decomposition residues floating
in the bulk can reduce the volume resistivity as they are subjected to ionic decomposition
to produce electrical charges by heat and the electrical field. Such a detrimental
effect of decomposition residues can be prevented by taking them up into the main
chain of the polymer and consequently the volume resistivity of the composition is
improved.
[0064] The degradation in the electrical properties of an insulating material can be effectively
avoided by the above three effects of the present invention. Additionally, the volume
resistivity and the breakdown strength of the composition are remarkably improved
after crosslinking.
[0065] Now, the present invention will be described further by way of examples.
(Test Methods)
(1) Test Method for Volume Resistivity
[0066] An electrode system as shown in Figs. 1(a) and 1(b) was used. The specimens were
tested by applying a DC voltage of 3,300 V at room temperature and at 90°C in a nitrogen
atmosphere. A vibrating reed type ampere meter (TR8411 available from Advantest, Co.,Ltd.)
was used for gauging the volume resistivity. Each specimen had a thickness of 0.3
mm and an effective electrode surface area of 19.6 cm
2. The volume resistivity was determined by the electrical current observed 10 minutes
after the start of applying the voltage. Each specimen was tested four times and the
average of the readings was used.
[0067] In Figs. 1(a) and 1(b) illustrating the electrode system, 11 denotes a main electrode
(50φ), 12 denotes a guard electrode (inner diameter 75φ, outer diameter 80φ), 13 denotes
a specimen and 14 denotes a high voltage electrode (80φ).
(2) Test Method for Breakdown Strength
[0068] An electrode system having fixed electrodes or so-called McKewon electrodes as shown
in Fig. 2 was used. The electrode system comprises a substrate 24 made of polymethylmethacrylate
and bored at the center to a diameter of 1/2 inch and electrodes 21 of stainless steel
balls with a diameter of 1/2 inch. Each specimen 22 was cut to a dice of 8 to 10 mm
and arranged between the electrodes. The gap between the specimen and the electrodes
was filled with deaerated epoxy resin, which was then hardened. The McKewon electrodes
were dipped into silicon oil contained in a vessel, which was then put into a thermostat
for observation. The voltage used for this breakdown test had an impulse waveform
of 1.2/50 µS and negative polarity. The waveform was observed by means of an oscilloscope
and the reading of the wave crest where breakdown occurred was recorded for each test.
The average of more than twenty readings was used.
[0069] In Fig. 2 illustrating the gauging system for the breakdown strength test, 21 denotes
a pair of stainless steel balls, 22 denotes a specimen, 23 denotes epoxy resin and
24 denotes a substrate made of polymethylmethacrylate.
(3) Observation of Water Trees
[0070] A water tree observing system having a configuration as described in Fig. 3 was used.
A voltage of 10 kV and 10 kHz was applied to each specimen at room temperature.
[0071] After the application of the voltage, the water tree was pigmented and microscopically
observed. The following ratings were used.
strongly observable |
x (poor) |
mildly observable |
Δ (good) |
slightly observable |
o (excellent) |
[0072] In Fig. 3 illustrating the water tree observing system, 31 denotes specimens being
observed water trees, 32 denotes a conducting plate, 33 denotes water, 34 denotes
a grounding electrode, 35 denotes vessels and 36 denotes a voltage applying electrode.
[Materials]
Component (A): polyolefin
[0073]
- A1-1:
- high pressure radical method polyethylene (LD) [density=0.919g/cm3, MI=1.0g/10min. trade name: Nisseki Rexlon W2000 - available from Nippon Petrochemicals
Co., Ltd.]
- A1-2:
- linear low density polyethylene (LL) [density=0.921g/cm3, MI=1.0g/10min. trade name: Nisseki Linirex AF3280 - available from Nippon Petrochemicals
Co., Ltd.]
- A1-3:
- polypropyrene (PP) [density=0.905g/cm3, MI=1.5g/10min. trade name: Nisseki Polypro F120K - available from Nippon Petrochemicals
Co., Ltd.]
- A2-1:
- maleic anhydride modified high pressure radical method polyethylene (MAn-LD) [A 0.75
parts by weight of maleic anhydride and a 0.05 parts by weight of
2,5-dimethyl-2,5-di(tert-butylperoxide) were added to a 100 parts by weight of LD
and they were preliminary mixed by means of a Henschel mixer and made to react at
200°C in a biaxial extruder. When examined by infrared spectroscopic analysis, a 1
g of the polymer contained maleic anhydride by 2.66x10-5 mols.]
- A2-2:
- acrylic acid modified high pressure radical method polyethylene (Ac-LD) [After compounding
acrylic acid and dicumylperoxide with LD, they were made to react at 200°C in an extruder.
When examined by infrared spectroscopic analysis, a 1 gram of the polymer contained
acrylic acid by 3.38x10-6 mols.]
- A2-3:
- ethylene-maleic anhydride random copolymer (Et-MAn) [A 380g of n-hexane and a 11g
of maleic anhydride in acetone solution (0.11g of maleic anhydride) were put in an
3.8 liter autoclave provided with a stirrer and having a plenum of nitrogen and 2,5-dimethyl-2,5-di(tert-butylperoxide)
was added thereto as a polymerization starter. Thereafter, a 1.700 g of ethylene was
introduced therein and the mixture was polymerized at 1,600kgf/cm2 and 190°C for an hour to produce an ethylene-maleic anhydride copolymer. When examined
by infrared spectroscopic analysis, a 1 gram of the polymer contained maleic anhydride
by 1.58x10-3 mols.]
- A2-4:
- ethylene-vinyl alcohol random copolymer (Et-VOL) [Prepared in a manner same as above.
When examined by infrared spectroscopic analysis, a 1 gram of the polymer contained
the alcohol group by 2.4x10-4 mols.]
- A2-5:
- ethylene-nitrostyrene copolymer (Et-Nst) (not according to the invention) [Prepared
in a manner same as above. When examined by infrared spectroscopic analysis, a 1 gram
of the polymer contained the nitro group by 2.38x10-4 mols.]
- A2-6:
- ethylene-acrylonitrile copolymer (Et-AN) [Prepared in a manner same as above. When
examined by infrared spectroscopic analysis, a 1 gram of the polymer contained the
nitro group by 2.38x10-4 mols.]
Component (B):
[0074]
- B1-1:
- polybutadiene (PB1) [average molecular weight 3,000, specific gravity 0.89g/cm3 trade name: Nisseki Butadiene B-3000 - available from Nippon Petrochemicals Co.,
Ltd.]
- B1-2:
- butadiene polymer (PB2) [specific gravity 0.89g/cm3 trade name: JSR RB820 - available from Japan Synthetic Rubber Co., Ltd.]
- B1-3:
- copolymer of 1,3-butadiene and cyclododeca-1,5,9-hexatriene (PB3) [1,3-butadiene and
cyclododeca-1,5,9-hexatriene were used at a molar ratio of 9:1 in the presence of
toluene and a 3-dimensional catalyst of cobalt triacetylacetate, triethylaluminum
and water and made to react for polymerization at 7°C. Thereafter, the low molecular
components were removed to produce a copolymer having an average molecular weight
of 2,500. When examined by infrared spectroscopic analysis, the vinyl bonding amounted
to 43%.]
- B1-4:
- liquid polyisoprene (PI) [average molecular weight 29,000, 740 Poise/38°C, trade name:
Kuraprene LIR-30 - available from Kuraray Co., Ltd.]
- B2-1:
- maleic anhydride modified polybutadiene (MAn-PB1) [average molecular weight 3,000,
specific gravity 0.89g/cm3 When examined by infrared spectroscopic analysis, a 1 gram of the polymer contained
maleic anhydride by 4.32x10-4 mols. trade name: Nisseki Polybutadiene M-2000 - available from Nippon Petrochemicals
Co., Ltd.]
- B2-2:
- acrylic acid modified polybutadiene (MAn-PB1) [average molecular weight 2,000, specific
gravity 0.91g/cm3 When examined by infrared spectroscopic analysis, a 1 gram of the polymer contained
acrylic acid by 2.20x10-4 mols. trade name: Nisseki Polybutadiene M-2000 - available from Nippon Petrochemicals
Co., Ltd.]
- B2-3:
- a mixture of ethylene-vinylalcohol copolymer (EVOL) (Prepared through copolymerization
and hydrolysis of ethylene and vinylester. A 1 gram of the copolymer contained the
residual alcohol group by 1.13x10-3 mols.) and polybutadiene (PB1)
- B2-4:
- maleic anhydrides-butadiene copolymer (MAn-PB3) [Prepared through heating and modification
in an autoclave. When examined by infrared spectroscopic analysis, a 1 gram of the
polymer contained maleic anhydride by 8.95x10-5 mols.]
- B2-5:
- maleic anhydrides modified liquid polyisoprene (MAn-PI) [Prepared through heating
and modification in an autoclave. When examined by infrared spectroscopic analysis,
a 1 gram of the polymer contained maleic anhydride by 2.87x10-4 mols.]
- B2-6:
- acrylic acid modified polybutadiene (MAn-PB1) [Prepared through heating and modification
in an monoaxial extruder. When examined by infrared spectroscopic analysis, a 1 gram
of the polymer contained acrylic acid by 3.25x10-4 mols.]
- B2-7:
- maleic anhydrides modified butadiene polymer (MAn-PB2) [Prepared through heating and
modification in an monoaxial extruder. When examined by infrared spectroscopic analysis,
a 1 gram of the polymer contained maleic anhydride by 3.44x10-4 mols.]
- B3:
- divinylbenzene (DVB)
Component (C):
[0075]
- C1-1 &
- ethylene-styrene random copolymer (Et-St) [Two
- C1-2:
- samples with different styrene concentrations were prepared by the high pressure radical
polymerization method. When examined by infrared spectroscopic analysis, a 1 gram
of the polymer contained styrene by C1-1 0.016 g (1.54x10-4 mols) and C1-2 0.164 g (1.58x10-3 mols)]
- C2-1:
- ethylene-styrene-maleic anhydride random copolymer (Et-St-MAn) [Prepared by introducing
styrene monomer and maleic anhydride into an autoclave provided with a stirrer and
then made to react for polymerization after throwing ethylene into the mixture. When
examined by infrared spectroscopic analysis, a 1 gram of the polymer contained styrene
by 0.121 g (1.16x10-3 mols) and maleic anhydride by 0.107 g (1.09x10-3 mols).]
- C2-2:
- maleic anhydride modified ethylene-styrene copolymer (MAn-Et-St) [Prepared by adding
dicumylperoxide to an ethylene-styrene copolymer produced by the high pressure radical
polymerization method and caused them to react with maleic anhydride. When examined
by infrared spectroscopic analysis, a 1 gram of the polymer contained styrene by 0.3616
g (3.4x10-4 mols) and maleic anhydride by 2.0x10-3 g (2.04x10-4 mols).]
- C2-3:
- polypropylene copolymer (PP-St-MAn) [Prepared by causing polypropylene to react with
styrene and maleic anhydride, using a radical generating agent. When examined by infrared
spectroscopic analysis, a 1 gram of the polymer contained styrene by 4.03g (3.86x10-5 mols) and maleic anhydride by 1.96x10-3 g (1.94x10-5 mols).]
[Examples 1 through 38][Comparative Examples 1 through 8]
[0077] Fig. 4 is a graph showing the performances of Examples 1 through 6 and those of Comparative
Examples 1, 4 and 5, expressed in terms of the relationship between the functional
group concentration (horizontal axis) and the volume resistivity (vertical axis).
The marks ○ and ● are the results of the examples according to the present invention,
and the other marks □ and ■ are the results of the comparative ones. Further, the
marks ○ and □ are the results at room temperature and the other marks ● and ■ are
the results at 90°C.
[0078] It will be seen that the volume resistivity of Examples 1 through 6 were remarkably
improved at both room temperature (RT) and 90°C by introducing functional groups of
B2-1 into the compositions. On the contrary, Comparative Example 1 where no functional
group was introduced and Comparative Examples 4 and 5 where the polymer was simply
modified with the functional group of A2-1 have poor volume resistivities which were
notably changed between RT and 90°C.
[0079] Fig. 5 is a graph showing the performances (marks ○, ●, Δ and ▲) of Examples 7 through
10 and 13 through 15 and those (the other marks □ and ■) of Comparative Examples 1,
4, 5 and 10. Note that the volume resistivity was improved by using A1-1 and A2-1
for (A) and also by adding B2-1 to C1-1.
[Preparation of Sample Cables]
[0080] Sample cables having a configuration as shown in Fig. 6 were prepared by using the
composition of Example 3. When tested, they performed remarkably well.
[0081] In Fig. 6 illustrating a sample cable, 41 denotes a conducting member which is a
bundle of conducting metal wires, 42 denotes an internal semiconducting layer, 43
denotes an insulating polymer composition layer, 44 denotes an external semiconducting
layer, 45 denotes an aluminum foil and 46 denotes a protective member (made of polyolefin
containing an inorganic flame retarding agent).
[Advantages of the Invention]
[0082] The present invention provides an electrically insulating polymer composition comprising
an olefinic polymer as a principal ingredient and also comprising specific functional
group containing monomeric units and/or aromatic ring containing monomeric units.
Such a polymer composition is excellent in the volume resistivity, the breakdown strength
and other electrically insulating properties. It is also sensitive to crosslinking
and, if crosslinked, it does not lose its remarkable volume resistivity, the breakdown
strength and other electrically insulating properties. Thus, a polymer composition
according to the present invention and a crosslinked material obtained from such a
composition can be used to form an insulating layer for wires or cables in general
and DC power cables in particular.
[0083] A polymer composition according to the present invention finds a wide variety of
applications including insulating materials for wires or cables in general and DC
power cables in particular to be used for electrical appliances, transportation equipment,
plants and factories.
1. An electrically insulating polymer composition comprising an olefinic polymer and
at least one type of functional group containing monomer units selected from monomer
units derived from monomers D1 through D3 at a rate of 5x10-7 to 5x10-3 mols per gram of the composition, and also comprising ethylenic linkages at a rate
of not smaller than 0.8 per 1,000 carbon atoms and/or aromatic ring containing monomer
units derived from monomer D4 at a rate of 5x10-7 to 5x10-3 mols per gram of the composition, wherein said monomers D1 through D4 have an ethylenic
linkage, said monomer D1 is a carbonyl group or carbonyl group derivative containing
monomer, said monomer D2 is a hydroxyl group containing monomer, said monomer D3 is
a nitrile group containing monomer, and said monomer D4 is an aromatic ring containing
monomer.
2. An electrically insulating polymer composition according to claim 1, wherein said
composition comprises a polymer having said functional group containing monomer units
derived from monomers D1 through D3, a polymer having monomer units containing two
or more ethylenic linkages and/or a polymer having said aromatic ring containing monomer
D4.
3. An electrically insulating polymer composition according to claim 1, wherein said
composition comprises at least one of component (A), component (B) and component (C)
as defined below;
component (A): at least one of (A1) and (A2) below;
(A1): an olefinic polymer, and
(A2): a random copolymer of olefin and at least one of said functional group containing
monomers D1 through D4 or a graft copolymer obtained by modifying an olefinic polymer
with at least one of said functional group containing monomers D1 through D4,
component (B): at least one of (B1) through (B3) below;
(B1): a homopolymer derived from a monomer containing two or more ethylenic linkages
or a copolymer of said monomer and ethylene,
(B2): a random copolymer of a monomer containing two or more ethylenic linkages
and at least one of said functional group containing monomers D1 through D4, a random
copolymer of a monomer containing two or more ethylenic linkages, ethylene and at
least one of said functional group containing monomers D1 through D4 or a graft copolymer
obtained by modifying a homopolymer derived from a monomer containing two or more
ethylenic linkages or a copolymer of said monomer and ethylene with at least one of
said functional group containing monomers D1 through D4, and
(B3): a compound containing two or more ethylenic linkages,
component (C): at least one of (C1) and (C2) below;
(C1): an olefinic polymer containing at least one aromatic ring, and
(C2): a random copolymer of an olefin, at least one of said functional group containing
monomers D1 through D3, and said aromatic ring containing monomer D4 or a graft copolymer
obtained by modifying an olefinic polymer containing aromatic rings with at least
one of said functional group containing monomers D1 through D3, or a graft copolymer
obtained by modifying a random copolymer of olefin and at least one of said functional
group containing monomers D1 through D3 with said aromatic ring containing monomer
D4.
4. An electrically insulating polymer composition according to claim 3, wherein said
composition comprises;
(A1) an olefinic polymer,
(B21) a graft copolymer obtained by modifying a homopolymer derived from a monomer
containing two or more ethylenic linkages or a copolymer of said monomer and ethylene
with said functional group containing monomer D1.
5. An electrically insulating polymer composition according to claim 3, wherein said
composition comprises;
(A1) an olefinic polymer,
(A21) a graft copolymer obtained by modifying an olefinic polymer with said functional
group containing monomer D1, and
(B21) a graft copolymer obtained by modifying a homopolymer derived from a monomer
containing two or more ethylenic linkages or a copolymer of said monomer and ethylene
with said functional group containing monomer D1.
6. An electrically insulating polymer composition according to claim 3, wherein said
composition comprises;
(A1) an olefinic polymer,
(A21) a graft copolymer obtained by modifying an olefinic polymer with said functional
group containing monomer D1, and
(B3) a compound having two or more ethylenic linkages.
7. An electrically insulating polymer composition according to claim 3, wherein said
composition comprises;
(B21) a graft copolymer obtained by modifying a homopolymer derived from a monomer
containing two or more ethylenic linkages or a copolymer of said monomer and ethylene
with said functional group containing monomer D1, and
(C1) an olefinic polymer containing at least one aromatic ring.
8. An electrically insulating polymer composition according to claim 3, wherein said
composition comprises;
(A21) a graft copolymer obtained by modifying an olefinic polymer with said functional
group containing monomer D1, and
(C1) an olefinic polymer containing at least one aromatic ring.
9. An electrically insulating polymer composition according to claim 3, wherein said
composition comprises;
(C1) an olefinic polymer containing at least one aromatic ring, and
(C21) a graft copolymer obtained by modifying an olefinic polymer with said functional
group containing monomer D1.
10. An electrically insulating polymer composition according to claim 3, wherein the olefinic
polymer as component (A) is one selected from the group consisting of high pressure
polymerization method polyethylene, high density polyethylene, medium density polyethylene,
linear low density polyethylene or polypropylene.
11. An electrically insulating polymer composition according to claim 3, wherein the homopolymer
derived from a monomer having two or more ethylenic linkages or the copolymer of said
monomer and ethylene as component (B) is one selected from the group consisting of
liquid polybutadiene, ethylene-acrylic acid copolymer or ethylene-vinyl(meth)acrylate
copolymer.
12. An electrically insulating polymer composition according to claim 1, wherein the functional
group containing monomer D1 is (meth)acrylic acid or maleic anhydride.
13. An electrically insulating polymer composition according to claim 3, wherein the olefin
polymer containing at least one aromatic ring as component (C) is a random copolymer
of ethylene-styrene or a graft copolymer obtained by modifying an olefin copolymer
with said aromatic ring containing monomer D4.
14. A wire or a cable having an insulating layer formed by an electrically insulating
polymer composition according to any of the claims 1 to 13 or a material prepared
by crosslinking said polymer composition.
15. A wire or a cable according to claim 14, wherein the insulating layer is formed by
a material prepared by crosslinking a polymer composition according to any of the
claims 1 to 13.
16. A DC power cable having an insulating layer formed by an electrically insulating polymer
composition according to any of the claims 1 to 13 or a material prepared by crosslinking
said polymer composition.
1. Elektrisch isolierende Polymerzusammensetzung, die ein Olefinpolymer und mindestens
eine Art von funktionelle Gruppen enthaltenden Monomereinheiten, die unter von Monomeren
D1 bis D3 abgeleiteten Monomereinheiten ausgewählt sind, in einem Anteil von 5x10-7 bis 5x10-3 Mol pro Gramm der Zusammensetzung, enthält, welche außerdem ethylenische Bindungen
in einer Rate von nicht weniger als 0,8 pro 1000 Kohlenstoffatome und/oder einen aromatischen
Ring enthaltende Monomereinheiten, die von einem Monomeren D4 abgeleitet sind, in
einem Anteil von 5x10-7 bis 5x10-3 Mol pro Gramm der Zusammensetzung enthält, wobei die Monomeren D1 bis D4 eine ethylenische
Bindung haben, das Monomere D1 ein Monomeres ist, das eine Carbonylgruppe oder ein
Derivat einer Carbonylgruppe enthält, das Monomere D2 ein eine Hydroxylgruppe enthaltendes
Monomeres, das Monomere D3 ein eine Nitrilgruppe enthaltendes Monomeres und das Monomere
D4 ein einen aromatischen Ring enthaltendes Monomeres ist.
2. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 1, wobei die Zusammensetzung
ein Polymeres, welches die von den Monomeren D1 bis D3 abgeleiteten funktionelle Gruppen
enthaltenden Monomereinheiten enthält, ein Polymeres, das Monomereinheiten aufweist,
die zwei oder mehr ethylenische Bindungen enthalten und/oder ein Polymeres, welches
die einen aromatischen Ring enthaltenden Monomereinheiten D4 enthält, umfaßt.
3. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 1, wobei die Zusammensetzung
mindestens eine der nachstehend definierten Komponente (A), Komponente (B) und Komponente
(C) enthält:
Komponente (A): mindestens eine der nachstehenden Komponenten (A1) und (A2),
(A1): ein Olefinpolymer und
(A2): ein statistisches Copolymer eines Olefins und mindestens eines der die funktionellen
Gruppen enthaltenden Monomeren D1 bis D4 oder ein Pfropfcopolymer, erhalten durch
Modifizieren eines Olefincopolymeren mit mindestens einem der die funktionellen Gruppen
enthaltenden Monomeren D1 bis D4,
Komponente (B): mindestens eine der nachstehenden Komponenten (B1) bis (B3):
(B1) : ein von einem Monomeren, das zwei oder mehr ethylenische Bindungen enthält,
abgeleitetes Homopolymer oder ein Copolymer dieses Monomeren und Ethylen,
(B2): ein statistisches Copolymer eines Monomeren, das zwei oder mehr ethylenische
Bindungen enthält und mindestens eines der die funktionellen Gruppen enthaltenden
Monomeren D1 bis D4, ein statistisches Copolymer eines Monomeren, das zwei oder mehr
ethylenische Bindungen enthält, mit Ethylen und mindestens einem der die funktionellen
Gruppen enthaltenden Monomeren D1 bis D4 oder ein Pfropfcopolymer, erhalten durch
Modifizieren eines Homopolymeren, das von einem zwei oder mehr ethylenische Bindungen
enthaltenden Monomeren abgeleitet ist, oder eines Copolymeren eines solchen Monomeren
und Ethylen mit mindestens einem der die funktionellen Gruppen enthaltenden Monomeren
D1 bis D4, und
(B3): eine Verbindung, die zwei oder mehr ethylenische Bindungen enthält,
Komponente (C): mindestens eine der nachstehenden Komponenten (C1) und (C2):
(C1): ein Olefinpolymer, das mindestens einen aromatischen Ring enthält und
(C2): ein statistisches Copolymer aus einem Olefin, mindestens einem der die funktionellen
Gruppen enthaltenden Monomeren D1 bis D3 und dem einen aromatischen Ring enthaltenden
Monomeren D4 oder ein Pfropfcopolymer, erhalten durch Modifizieren eines aromatische
Ringe enthaltenden Olefinpolymeren mit mindestens einem der die funktionellen Gruppen
enthaltenden Monomeren D1 bis D3, oder ein Pfropfcopolymer, erhalten durch Modifizieren
eines statistischen Copolymeren eines Olefins und mindestens eines der die funktionellen
Gruppen enthaltenden Monomeren D1 bis D3 mit dem einen aromatischen Ring enthaltenden
Monomeren D4.
4. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei die Zusammensetzung
umfaßt:
(A1) ein Olefinpolymer,
(B21) ein Pfropfcopolymer, das durch Modifizieren eines Homopolymeren, das von einem
Monomeren mit zwei oder mehr ethylenischen Bindungen abgeleitet ist, oder eines Copolymeren
dieses Monomeren und Ethylen mit dem eine funktionelle Gruppe enthaltenden Monomeren
D1 erhalten ist.
5. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei die Zusammensetzung
umfaßt:
(A1) ein Olefinpolymer,
(A21) ein Pfropfcopolymer, das durch Modifizieren eines Olefinpolymeren mit dem
eine funktionelle Gruppe enthaltenden Monomeren D1 erhalten wurde und
(B21) ein Pfropfcopolymer, das durch Modifizieren eines Homopolymeren, das von einem
zwei oder mehr ethylenische Bindungen enthaltenden Monomeren abgeleitet ist, oder
eines Copolymeren dieses Monomeren und Ethylen mit dem die funktionelle Gruppe enthaltenden
Monomeren D1 erhalten wurde.
6. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei die Zusammensetzung
umfaßt:
(A1) ein Olefinpolymer,
(A21) ein Pfropfcopolymer, das durch Modifizieren eines Olefinpolymeren mit dem
eine funktionelle Gruppe enthaltenden Monomeren D1 erhalten wurde, und
(B3) eine Verbindung, die zwei oder mehr ethylenische Bindungen enthält.
7. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei die Zusammensetzung
umfaßt:
(B21) ein Pfropfcopolymer, das durch Modifizieren eines von einem zwei oder mehr
ethylenische Bindungen enthaltenden Monomeren abgeleiteten Homopolymeren ist, oder
eines Copolymeren dieses Monomeren und Ethylen mit dem eine funktionelle Gruppe enthaltenden
Monomeren D1 erhalten wurde und
(C1) ein mindestens einen aromatischen Ring enthaltendes Olefinpolymer.
8. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei die Zusammensetzung
umfaßt:
(A21) ein Pfropfcopolymer, das durch Modifizieren eines Olefinpolymeren mit dem
eine funktionelle Gruppe enthaltenden Monomeren D1 erhalten wurde und
(C1) ein mindestens einen aromatischen Ring enthaltendes Olefinpolymer.
9. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei die Zusammensetzung
umfaßt:
(C1) ein mindestens einen aromatischen Ring enthaltendes Olefinpolymer, und
(C21) ein Pfropfcopolymer, das durch Modifizieren eines Olefinpolymeren mit dem
eine funktionelle Gruppe enthaltenden Monomeren D1 erhalten wurde.
10. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei das Olefinpolymer
als Komponente (A) aus der Gruppe ausgewählt ist, die aus durch Hochdruckpolymerisation
gebildetem Polyethylen, Polyethylen hoher Dichte, Polyethylen mittlerer Dichte, linearem
Polyethylen niederer Dichte oder Polypropylen besteht.
11. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei das Homopolymer,
das von einem zwei oder mehr ethylenische Bindungen enthaltenden Monomeren abgeleitet
ist, oder das Copolymer dieses Monomeren und Ethylen als Komponente (B) aus der aus
flüssigem Polybutadien, Ethylen-Acrylsäure-Copolymer oder Ethylen-Vinyl(meth)acrylat-Copolymer
bestehenden Gruppe ausgewählt ist.
12. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 1, wobei das eine funktionelle
Gruppe enthaltende Monomere D1 (Meth)acrylsäure oder Maleinsäureanhydrid ist.
13. Elektrisch isolierende Polymerzusammensetzung nach Anspruch 3, wobei das mindestens
einen aromatischen Ring enthaltende Olefinpolymer als Komponente (C) ein statistisches
Ethylen-Styrol-Copolymer oder ein Pfropfcopolymer ist, das durch Modifizieren eines
Olefin-Copolymeren mit dem einen aromatischen Ring enthaltenden Monomeren D4 erhalten
wurde.
14. Draht oder Kabel, das mit Hilfe einer elektrisch isolierenden Polymerzusammensetzung
nach einem der Ansprüche 1 bis 13 oder eines durch Vernetzen dieser Polymerzusammensetzung
hergestelltem Materials gebildet ist.
15. Draht oder Kabel nach Anspruch 14, wobei die Isolierschicht aus einem Material gebildet
ist, das durch Vernetzen einer Polymerzusammensetzung nach einem der Ansprüche 1 bis
13 hergestellt wurde.
16. DC-Starkstromkabel, das eine Isolierschicht aufweist, die aus einer elektrisch isolierenden
Polymerzusammensetzung nach einem der Ansprüche 1 bis 13 oder einem durch Vernetzen
dieser Polymerzusammensetzung erhaltenen Material gebildet wurde.
1. Composition de polymère d'isolation électrique comprenant un polymère oléfinique et
au moins un type de groupe fonctionnel contenant des motifs monomères sélectionnés
à partir de motifs monomères dérivés de monomères D1 à D3 à un taux de 5x10-7 à 5X10-3 moles par gramme de la composition, et comprenant également des liaisons éthyléniques
à un taux non inférieur à 0,8 pour 1000 atomes de carbone et/ou un noyau aromatique
contenant des motifs monomères dérivés du monomère D4 à un taux de 5x10-7 à 5X10-3 moles par gramme de la composition, dans laquelle lesdits monomères D1 à D4 ont un
liaison oléfinique, ledit monomère D1 est un groupe carbonyle ou un dérivé de groupe
carbonyle contenant du monomère, ledit monomère D2 est un groupe hydroxyle contenant
du monomère, ledit monomère D3 est un groupe nitrile contenant du monomère, et ledit
monomère D4 est un noyau aromatique contenant du monomère.
2. Composition de polymère d'isolation électrique selon la revendication 1, dans laquelle
ladite composition comprend un polymère ayant ledit groupe fonctionnel contenant des
motifs monomères dérivés de monomères D1 à D3, un polymère ayant des motifs monomères
contenant deux ou plusieurs liaisons oléfiniques et/ou un polymère ayant ledit noyau
aromatique contenant du monomère D4.
3. Composition de polymère d'isolation électrique selon la revendication 1, dans laquelle
ladite composition comprend au moins l'un des composant (A), composant (B) et composant
(C) comme définis ci-dessous ;
le composant (A) : au moins l'un de (A1) et (A2) ci-dessous ;
(A1) : un polymère oléfinique, et
(A2) : un copolymère statistique d'oléfine et au moins l'un dudit groupe fonctionnel
contenant des monomères D1 à D4 ou un copolymère greffé obtenu en modifiant un polymère
oléfinique avec au moins l'un dudit groupe fonctionnel contenant des monomères D1
à D4 ;
le composant (B) : au moins l'un de (B1) à (B3) ci-dessous :
(B1) : un homopolymère dérivé d'un monomère contenant deux ou plusieurs liaisons oléfiniques
ou un copolymère dudit monomère et éthylène,
(B2) : un copolymère statistique d'un monomère contenant deux ou plusieurs liaisons
oléfiniques et au moins l'un dudit groupe fonctionnel contenant des monomères D1 à
D4, un copolymère statistique d'un monomère contenant deux ou plusieurs liaisons oléfiniques,
éthylène et au moins l'un dudit groupe fonctionnel contenant des monomères D1 à D4
ou un copolymère greffé obtenu en modifiant un homopolymère dérivé d'un monomère contenant
deux ou plusieurs liaisons oléfiniques ou un copolymère dudit monomère et éthylène
avec au moins l'un dudit groupe fonctionnel contenant des monomères D1 à D4, et
(B3) : un composé contenant deux ou plusieurs liaisons oléfiniques,
le composant (C) : au moins l'un de (C1) et (C2) ci-dessous ;
(C1) : un polymère oléfinique contenant au moins un noyau aromatique, et
(C2) : un copolymère statistique d'un oléfine, au moins l'un dudit groupe fonctionnel
contenant des monomères D1 à D3, et ledit noyau aromatique contenant le monomère D4
ou un copolymère greffé obtenu en modifiant un polymère oléfinique contenant des noyaux
aromatiques avec au moins l'un dudit groupe fonctionnel contenant des monomères D1
à D3, ou un copolymère greffé obtenu en modifiant un copolymère statistique d'oléfine
et au moins l'un dudit groupe fonctionnel contenant des monomères D1 à D3 avec ledit
noyau aromatique contenant du monomère D4.
4. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
ladite composition comprend ;
(A1) un polymère oléfinique,
(B21) un copolymère greffé obtenu en modifiant un homopolymère dérivé d'un monomère
contenant deux ou plusieurs liaisons oléfiniques ou un copolymère dudit monomère et
éthylène avec ledit groupe fonctionnel contenant du monomère D1
5. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
ladite composition comprend ;
(A1) un polymère oléfinique,
(A21) un copolymère greffé obtenu en modifiant un polymère oléfinique avec ledit groupe
fonctionnel contenant du monomère D1, et
(B21) un copolymère greffé obtenu en modifiant un homopolymère dérivé d'un monomère
contenant deux ou plusieurs liaisons oléfiniques ou un copolymère dudit monomère et
éthylène avec ledit groupe fonctionnel contenant le monomère D1.
6. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
ladite composition comprend ;
(A1) un polymère oléfinique,
(A21) un copolymère greffé obtenu en modifiant un polymère oléfinique avec ledit groupe
fonctionnel contenant le monomère D1, et
(B3) un composé ayant deux ou plusieurs liaisons oléfiniques.
7. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
ladite composition comprend ;
(B21) un copolymère greffé obtenu en modifiant un homopolymère dérivé d'un monomère
contenant deux ou plusieurs liaisons oléfiniques ou un copolymère dudit monomère et
éthylène avec ledit groupe fonctionnel contenant le monomère D1, et
(C1) un polymère oléfinique contenant au moins un noyau aromatique.
8. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
ladite composition comprend ;
(A21) un copolymère greffé obtenu en modifiant un polymère oléfinique avec ledit groupe
fonctionnel contenant le monomère D1, et
(C1) un polymère oléfinique contenant au moins un noyau aromatique.
9. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
ladite composition comprend ;
(C1) un polymère oléfinique contenant au moins un noyau aromatique, et
(C21) un copolymère greffé obtenu en modifiant un polymère oléfinique avec ledit groupe
fonctionnel contenant le monomère D1.
10. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
le polymère oléfinique en tant que composant (A) est un choisi dans le groupe consistant
en du polyéthylène de procédé de polymérisation à haute pression, du polyéthylène
à forte densité, du polyéthylène à densité moyenne, du polyéthylène ou polypropylène
linéaire à faible densité.
11. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
l'homopolymère dérivé d'un monomère ayant deux ou plusieurs liaisons oléfiniques ou
du copolymère dudit monomère et éthylène en tant que composant (B) est un choisi dans
le groupe consistant en du polybutadiène liquide, du copolymère acide éthylène-acrylique
ou du copolymère (méth.)acrylate éthylène-vinylique.
12. Composition de polymère d'isolation électrique selon la revendication 1, dans laquelle
le groupe fonctionnel contenant le monomère D1 est de l'anhydride (méth.)acrylique
ou maléique.
13. Composition de polymère d'isolation électrique selon la revendication 3, dans laquelle
le polymère oléfinique contenant au moins un noyau aromatique en tant que composant
(C) est un copolymère statistique d'éthylène styrène ou un copolymère greffé obtenu
en modifiant un copolymère oléfinique avec ledit noyau aromatique contenant le monomère
D4.
14. Fil ou câble ayant une couche isolante formée par une composition de polymère d'isolation
électrique selon l'une quelconque des revendications 1 à 13, ou un matériau préparé
en réticulant ladite composition de polymère.
15. Fil ou câble selon la revendication 14, dans laquelle la couche isolante est formée
par un matériau préparé réticulant une composition de polymère selon l'une quelconque
des revendications 1 à 13.
16. Câble d'alimentation CC ayant une couche isolante formée par une composition de polymère
d'isolation électrique selon l'une quelconque des revendications 1 à 13 ou un matériau
préparé par réticulation de ladite composition de polymère.