U.S. patent application number 10/012519 was filed with the patent office on 2002-08-15 for electrical wire having resin composition covering.
This patent application is currently assigned to SUMITOMO WIRING SYSTEMS, LTD.. Invention is credited to Fujimoto, Hiroshi, Hase, Tatsuya, Matsumoto, Shinichi, Sato, Masashi, Sugita, Takahiko.
Application Number | 20020108772 10/012519 |
Document ID | / |
Family ID | 27481863 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020108772 |
Kind Code |
A1 |
Hase, Tatsuya ; et
al. |
August 15, 2002 |
Electrical wire having resin composition covering
Abstract
An electrical wire and a method of making the electrical wire
are provided. The electrical wire includes a conductor and an
electrically insulating covering formed on the conductor. The
electrically insulating covering is a resin composition including a
first polymer, a second polymer and filler particles. The first
polymer has a higher bonding affinity to the filler particles than
the second polymer. The filler particles are coated with the first
polymer and the coated filler particles are embedded in a matrix of
the second polymer. The electrical wire is suitable for use in
motor vehicles.
Inventors: |
Hase, Tatsuya; (Yokkaichi,
JP) ; Sugita, Takahiko; (Yokkaichi, JP) ;
Fujimoto, Hiroshi; (Yokkaichi, JP) ; Sato,
Masashi; (Yokkaichi, JP) ; Matsumoto, Shinichi;
(Yokkaichi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
SUMITOMO WIRING SYSTEMS,
LTD.
Yokkaichi-city
JP
|
Family ID: |
27481863 |
Appl. No.: |
10/012519 |
Filed: |
December 12, 2001 |
Current U.S.
Class: |
174/120C |
Current CPC
Class: |
C08L 23/10 20130101;
C08L 23/06 20130101; C08L 23/0853 20130101; H01B 7/295 20130101;
C08L 2666/24 20130101; C08L 2666/04 20130101; C08L 2666/04
20130101; C08L 2666/24 20130101; C08L 2666/24 20130101; C08L 23/10
20130101; C08L 2666/04 20130101; C08L 23/0815 20130101; C08L
2201/02 20130101; C08L 2203/202 20130101; C08L 23/10 20130101; C08K
3/22 20130101; C08L 23/0815 20130101; C08L 51/06 20130101; C08L
23/0815 20130101; C08L 23/06 20130101; C08K 3/22 20130101; C08L
23/10 20130101; C08L 23/06 20130101; C08L 53/02 20130101 |
Class at
Publication: |
174/120.00C |
International
Class: |
H01B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2000 |
JP |
2000-377498 |
Mar 26, 2001 |
JP |
2001-087906 |
Mar 26, 2001 |
JP |
2001-087907 |
Mar 26, 2001 |
JP |
2001-087908 |
Claims
What is claimed is:
1. An electrical wire, comprising: a conductor; and an electrically
insulating covering formed on the conductor; wherein: the covering
is a resin composition comprising at least one first polymer, at
least one second polymer and filler particles; the at least one
first polymer has a higher bonding affinity to the filler particles
than the at least one second polymer; and the filler particles are
coated with the at least one first polymer and the coated filler
particles are embedded in a matrix of the at least one second
polymer.
2. The electrical wire of claim 1, wherein the filler particles are
inorganic filler particles.
3. The electrical wire of claim 2, wherein the inorganic filler
particles are comprised of at least one filler material selected
from the group consisting of carbon materials, metal oxides, metal
hydroxides, metal carbonates, metal sulfates, metal silicates and
metal nitrides.
4. The electrical wire of claim 3, wherein the inorganic filler
particles are comprised of at least one metal hydroxide.
5. The electrical wire of claim 1, wherein the filler particles are
surface coated with a coupling agent.
6. The electrical wire of claim 5, wherein the coupling agent is
selected from the group consisting of silane coupling agents, fatty
acids and salts of fatty acids.
7. The electrical wire of claim 1, wherein the at least one first
polymer comprises a reactive functional group that promotes bonding
of the at least one first polymer with the filler particles.
8. The electrical wire of claim 7, wherein the reactive functional
group is selected from the group consisting of carboxylic acid
groups, carboxylic acid anhydride groups and carboxylic acid ester
groups.
9. The electrical wire of claim 8, wherein the at least one first
polymer is selected from the group consisting of acid
anhydride-modified ethylene-vinyl acetate copolymers, acid
anhydride-modified ethylene-ethyl acrylate copolymers, acid
anhydride-modified ethylene-propylene rubbers, acid
anhydride-modified low density polyethylenes, acid
anhydride-modified linear low density polyethylenes, acid
anhydride-modified poly(propylene-ethylene/propylene) copolymers,
acid anhydride-modified styrene-butadiene rubbers, and acid
anhydride-modified hydrogenated styrene-butadiene rubbers.
10. The electrical wire of claim 1, wherein the at least one second
polymer is selected from the group consisting of propylene
polymers, ethylene polymers, and ethylene/propylene copolymers.
11. A method of making an electrical wire, comprising: forming a
resin composition comprising at least one first polymer, at least
one second polymer and filler particles, the at least one first
polymer having a higher bonding affinity to the filler particles
than the at least one second polymer, the filler particles being
coated with the at least one first polymer, and the coated filler
particles being embedded in a matrix of the at least one second
polymer; and applying the resin composition to an electrical
conductor to form an electrically insulating covering on the
electrical conductor; wherein forming the resin composition
comprises one of: (i) first kneading the filler particles and the
at least one first polymer to form a mixture and subsequently
kneading the mixture and the at least one second polymer; and (ii)
kneading the filler particles, the at least one first polymer and
the at least one second polymer together simultaneously.
12. The method of claim 11, wherein forming the resin composition
comprises first kneading the filler particles and the at least one
first polymer to form a mixture, and subsequently kneading the
mixture and the at least one second polymer.
13. The method of claim 11, wherein forming the resin composition
comprises kneading the filler particles, the at least one first
polymer and the at least one second polymer together
simultaneously.
14. The method of claim 11, wherein the filler particles are
comprised of an inorganic filler.
15. The method of claim 14, wherein the inorganic filler is
selected from the group consisting of carbon materials, metal
oxides, metal hydroxides, metal carbonates, metal sulfates, metal
silicates and metal nitrides.
16. The method of claim 15, wherein the inorganic filler is
comprised of at least one metal hydroxide.
17. The method of claim 11, wherein the filler particles are
surface treated with a coupling agent.
18. The method of claim 17, wherein the coupling agent is selected
from the group consisting of silane coupling agents, fatty acids
and salts of fatty acids.
19. The method of claim 11, wherein the at least one first polymer
comprises a reactive functional group that promotes bonding of the
at least one first polymer with the filler particles.
20. The method of claim 19, wherein the reactive functional group
is selected from the group consisting of carboxylic acid groups,
carboxylic acid anhydride groups and carboxylic acid ester
groups.
21. The method of claim 20, wherein the at least one first polymer
is selected from the group consisting of acid anhydride-modified
ethylene-vinyl acetate copolymers, acid anhydride-modified
ethylene-ethyl acrylate copolymers, acid anhydride-modified
ethylene-propylene rubbers, acid anhydride-modified low density
polyethylenes, acid anhydride-modified linear low density
polyethylenes, acid anhydride-modified
poly(propylene-ethylene/propylene) copolymers, acid
anhydride-modified styrene-butadiene rubbers, and acid
anhydride-modified hydrogenated styrene-butadiene rubbers.
22. The method of claim 11, wherein said second polymer is selected
from the group consisting of propylene polymers, ethylene polymers,
and ethylene/propylene copolymers.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] This invention relates to an electrical wire having a
halogen-free resin composition as an electrically insulating
covering on an electrical conductor core.
[0003] 2. Description of Related Art
[0004] Polyvinyl chloride has been much used as the covering
material of electrical wire used in automobiles, because it is
superior in properties such as mechanical strength, extrusion
processability, flexibility and coloring property. However, with
recent concern for the global environment, halogen-free resin
material has come to be used for the production of automobile parts
including the covering of electrical wires in an automobile in
place of polyvinyl chloride, because polyvinyl chloride discharges
a harmful halogen gas on combustion.
[0005] A halogen-free resin composition, in which a metal hydroxide
is blended with a polyolefin-based polymer as a flame-retardant, is
known as a wear resistant resin composition that does not generate
poisonous gas such as a halogen gas on combustion. See, for
example, JP-A-7-176219 and JP-A-7-78518. So that the
flame-retardant resin composition has a self-extinction property, a
large quantity of filler must be added. However, the large quantity
of filler causes problems with various aspects of mechanical
strength, including reductions in wear resistance, tensile strength
and the like.
[0006] Various fillers have been proposed for improving the
properties of such resin compositions. For example, metal oxides
such as titanium oxide and the like are used as a pigments. Metal
hydroxides such as magnesium hydroxide, aluminum hydroxide and the
like, as mentioned above, are added in order to impart flame
resistance to resin compositions. Calcium carbonate, talc, clay,
silica and the like are used to increase bulk. Carbon fiber, glass
fiber, talc, mica and the like are added for reinforcement.
[0007] However, polymer resins typically do not have a great
affinity for such fillers. Accordingly, the filler particles often
become mutually coagulated to form lumps of filler particles in a
resin phase when the filler is compounded with the resin. Thus, it
is difficult to achieve a resin having a homogeneous distribution
of the filler in the resin phase.
SUMMARY OF THE INVENTION
[0008] To prevent coagulation of the filler in the resin
composition, surface treated fillers are often employed.
Surface-treatment agents include silane-based agents,
titanate-based agents, aluminum-based agents, fatty acid-based oils
and fats, waxes, surfactants, and the like. However, use of such
surface-treated fillers can reduce mechanical strength, cause
whitening of the wire covering on bending, result in poor
processing properties, and the like.
[0009] Accordingly, an object of this invention is to provide an
electrical wire having a resin composition covering in which a
filler is homogeneously dispersed without coagulation. Another
object of this invention is to provide a method for producing such
a wire.
[0010] According to this invention, there is provided an electrical
wire having a conductor and an electrically insulating covering on
the conductor. The covering is a resin composition comprising at
least one first polymer, at least one second polymer and filler
particles. The at least one first polymer has a higher bonding
affinity for the filler particles than the at least one second
polymer. The filler particles are coated with the first polymer and
the coated filler particles are embedded in a matrix of the second
polymer.
[0011] According to this invention there is also provided a method
of making an electrical wire which comprises forming a resin
composition comprising at least one first polymer, at least one
second polymer and filler particles. The first polymer has a higher
bonding affinity for the filler particles than the second polymer.
The filler particles are coated with the first polymer and the
coated filler particles are embedded in a matrix of the second
polymer. The method also comprises applying the resin composition
to an electrical conductor to form an electrically insulating
covering thereon. Forming the resin composition can comprise first
kneading the filler particles and the first polymer to form a
mixture and subsequently kneading the mixture and the second
polymer, or alternatively kneading the filler particles and the
first and second polymers together at the same time.
[0012] These and other features and advantages of this invention
are described in, or are apparent from, the following detailed
description of various exemplary embodiments of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Various exemplary embodiments of this invention will be
described in detail, with reference to the following figures,
wherein:
[0014] FIG. 1 is a micrograph produced by an electron microscope
showing the structure of the resin composition obtained in Example
1.
[0015] FIG. 2 is a micrograph produced by an electron microscope
showing the structure of the resin composition obtained in
Comparative Example 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0016] In the present specification, including the claims, the term
"filler" refers not only to mere fillers, but also to various
additives and/or compounding agents that are conventionally added
to improve resins.
[0017] The filler used in this invention may either be an inorganic
filler or an organic filler. Inorganic fillers are preferred.
Examples of suitable fillers include carbon materials, metal
oxides, metal hydroxides, metal carbonates, metal sulfates, metal
silicates, metal nitrides and combinations thereof. Metal compounds
can include metals such as alkali metals, alkaline earth metals and
transition metals. These fillers can be used alone or in
combination. Of the metal compounds, metal hydroxides, such as
magnesium hydroxide, aluminum hydroxide and the like, are preferred
as fillers in resin compositions for electric wire because the
compositions impart flame retarding properties. The resin
compositions of this invention are, thus, desirably fire resistant
compositions. For this purpose, the resin composition is preferably
free of fibrous fillers. Preferably a metal hydroxide, or mixture
of metal hydroxides, is the only filler present in the resin
composition.
[0018] The filler particles used in this invention may be untreated
or treated. Preferably the filler particles of this invention have
been subjected to surface treatment with a coupling agent prior to
mixing with the first and second polymers. Coupling agents can
include silane coupling agents, fatty acids or salts of fatty
acids. Since the dispersibility of the filler is improved by the
first polymer coating, the filler coated with first polymer
according to this invention can have high dispersibility without
surface-treatment with the coupling agent. Silane coupling agents
include, for example, aminosilane coupling agents, vinylsilane
coupling agents, epoxysilane coupling agents, methacryloxysilane
coupling agents, and the like. Exemplary fatty acids or salts
thereof include higher fatty acids (e.g. having at least 12 carbon
atoms), such as stearic acid, oleic acid, or the like, and their
salts.
[0019] The first polymer has a bonding affinity for the filler. The
first polymer, which is used to coat the particle surface of the
filler, is preferably a polymer having a reactive functional group
that promotes binding of the first polymer with the filler particle
surface. Exemplary functional groups include carboxylic acid groups
(including carboxylic acid ester groups), carboxylic anhydride
groups, epoxy groups, hydroxy groups, amino groups, and the
like.
[0020] These functional groups can be introduced to the first
polymer by conducting polymerization using a monomer having such a
functional group, or by graft-copolymerizing a monomer having the
functional group to a skeleton polymer. In various exemplary
embodiments, functional groups are present on the first polymer
before the first polymer is mixed with the filler particles.
Polymers having carboxylic acid groups or carboxylic acid anhydride
groups, have a high affinity for inorganic fillers, and in
particular for metal hydroxides. To introduce carboxylic acid
groups or carboxylic anhydride groups, a monomer having an
unsaturated carboxylic acid group or its anhydride or ester can be
employed. Exemplary compositions include maleic acid and fumaric
acid, and anhydrides, monoesters or diesters thereof, and the
like.
[0021] Epoxy groups can be introduced to the first polymer by
employing compounds having glycidyl groups, such as, for example,
methyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether,
and the like.
[0022] The ratio of the monomer having the functional group to the
total polymer is typically from about 0.01% to about 30% by weight
and preferably from about 0.1% to about 10% by weight.
[0023] Exemplary first polymers, to which the functional group is
introduced, include, but are not limited to, propylene
homopolymers, propylene block or random copolymers, high density
polyethylenes (HDPEs), linear low density polyethylenes (LLDPEs),
low density polyethylenes (LDPEs), ultra low density polyethylenes,
polybutenes, polystyrenes, ethylene-vinyl acetate copolymers,
ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate
copolymers, ethylene-propylene rubbers, ethylene-butene rubbers,
olefin-based elastomers (e.g., poly(propylene-ethylene/propylene)
copolymers and the like), and styrene-based elastomers.
Styrene-based elastomers can include, for example, block copolymers
having polystyrene segments and rubber segments, such as
polybutadienes (e.g., SBS, SBR), polyisoprenes (e.g., SIS,SER),
ethylene/butadienes, the hydrogenated products of such compounds
(SEBS, HSBR, SEPS, HSIR).
[0024] Polymers comprising one or more acid anhydride group have a
high affinity for inorganic fillers, and in particular, metal
hydroxides. Exemplary polymers containing an acid anhydride group
that have a good affinity for fillers include, but are not limited
to, acid anhydride-modified ethylene-vinyl acetate copolymers, acid
anhydride-modified ethylene-ethyl acrylate copolymers, acid
anhydride-modified ethylene-propylene rubbers, acid
anhydride-modified low density polyethylenes, acid
anhydride-modified linear low density polyethylenes, acid
anhydride-modified poly(propylene-ethylene/propylene) copolymers,
acid anhydride-modified styrene-butadiene rubbers, and acid
anhydride-modified hydrogenated styrene-butadiene rubbers.
[0025] In various exemplary embodiments of this invention in which
a polymer modified with a carboxylic acid group or a carboxylic
acid anhydride group is used as the first polymer, and a metal
hydroxide is used as the filler, the composition preferably
includes no component, other than the metal hydroxide, which reacts
with the carboxylic acid or acid anhydride group. It is desired
that the first polymer bonds directly to the metal hydroxide
particles, during mixing or extrusion, to improve the mixing and
dispersion of the metal hydroxide particles in the composition.
[0026] The amount of the first polymer used for coating the filler
may be suitably selected according to the filler that is employed,
and is not particularly limited. However, the first polymer is
preferably present in an amount that does not exceed about 50% by
weight, relative to the total polymer content. The first polymer is
more preferably present in an amount between about 3% and about 40%
by weight. The second polymer is, thus, preferably present in an
amount of at least about 50%, more preferably in an amount of from
about 60% to about 97%, by weight.
[0027] The resin composition used in this invention includes the
filler coated with the above-mentioned first polymer and the second
polymer, which is different from the first polymer. All of the
polymers used in the resin composition are preferably halogen-free.
In various exemplary embodiments, there are no polymer components
present other than the first and second polymers. For example, in
such embodiments where the resin composition includes only a single
first polymer and only a single second polymer, there are only two
polymer components in the resin composition.
[0028] The second polymer is not particularly limited, and may be
selected with respect to its compatibility with the first polymer,
and the use of the resulting resin composition. For coating an
electric wire, an olefin-based polymer is preferred as the second
polymer. Exemplary olefin-based polymers include propylene polymers
such as homopolymers or propylene random or block copolymers (e.g.
with ethylene); polyethylenes such as high density polyethylenes,
linear low density polyethylenes, low density polyethylenes, ultra
low density polyethylenes, and the like; polybutene polymers;
polystyrenes and styrene copolymers; ethylene copolymers such as
ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate
copolymers, and the like; olefin-based elastomers such as
poly(propylene-ethylene/propylene) copolymers and the like; and
styrene-based elastomers such as styrene-butadiene block
copolymers, styrene-ethylene-propylene block copolymers, or
copolymers that are obtained by saturating unsaturated double bonds
in these copolymers by hydrogenation, and the like. These polymers
can be used alone or in combination. For processing reasons, a
single second polymer is preferred.
[0029] When the first polymer is an acid anhydride-modified
polymer, it is preferred that the second polymer is a propylene
polymer, an ethylene polymer or a propylene/ethylene copolymer.
[0030] Exemplary propylene polymers include propylene homopolymers
and propylene copolymers having propylene as a main component
(e.g., 50% by weight or more). Such propylene polymers can include
propylene-ethylene block or random copolymers and the like.
[0031] Exemplary ethylene polymers include ethylene homopolymers
and ethylene copolymers having ethylene as a main component (e.g.,
50% by weight or more). Such ethylene polymers can include
ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate
copolymers, ethylene-methyl methacrylate copolymers, and the
like.
[0032] The resin composition used as a wire covering according to
this invention can be produced by first mixing the filler and the
first polymer. Alternatively, since the first polymer has a higher
affinity for the filler than the second polymer, the first polymer
preferentially coats the filler particles. Accordingly, the
composition can be made by simultaneously mixing and kneading the
filler, the first polymer and the second polymer.
[0033] In this regard, the production process for the resin
composition according to this invention is not particularly
limited. The resin composition may be produced by kneading the
filler and the first polymer, and subsequently kneading the
obtained mixture and the second polymer. Alternatively, the resin
composition may be produced by simultaneously kneading the filler,
the first polymer and the second polymer. Since the first polymer
has higher affinity for the filler than the second polymer, it more
easily adheres to the filler particles than the second polymer.
Therefore, a morphology can be achieved in which the first polymer
coats the filler particles and the second polymer fills the space
between the coated filler particles. Such a morphology is known as
a "spotted" or "island" structure, in which the second polymer is
in "continuous phase" or a matrix, and the coated filler particles
are in "discontinuous phase." This morphology is later described
and illustrated with reference to a electron micrograph of the
resin composition in the Examples.
[0034] The proportion of the filler in the resin composition may be
suitably selected according to the use of the resin composition,
the types of first polymer and second polymer that are selected,
the type of the filler, and the like. Alternatively, the proportion
of the filler in the resin may be a conventional proportion.
However, the coated filler in this invention has good
dispersibility and is therefore homogeneously dispersed in the
polymer, so that in suitable cases a larger quantity than a
conventional compounding amount can be included. Alternatively, a
smaller amount of filler may used to obtain the same effect.
[0035] In addition to the filler, various compounding agents can be
added to the resin composition according to this invention.
Exemplary compounding agents include those conventionally used in
electric wire-coating resin materials. For example, the compounding
agents can include thermal stabilizers such as oxidation inhibitors
and the like; metal deactivators such as copper inhibitors and the
like; lubricants such as fatty acid-based lubricants, fatty acid
amide-based lubricants, metal soaps, hydrocarbon-based lubricants
(waxes), ester-based lubricants, silicone-based lubricants and the
like; coupling agents; softening agents such as process oils and
the like; crosslinking agents; and the like.
[0036] The resin composition of this invention can be crosslinked
if desired. For, for example, such cross linking may be desirable
in applications if high heat resistance is required. Cross-linking
can be carried out using a chemical cross-linking agents or using
radiation (for example, ultra violet rays radiation, electron beam
radiation, and the like). In various exemplary embodiments, the
polymers of the resin composition are not cross-linked. In such
embodiments, the composition is free from cross-linking agents,
such as peroxide. Further, in various exemplary embodiments, the
composition as applied as a wire covering, is free from
cross-linking agents and decomposition products of cross-linking
agents.
[0037] The resin composition of this invention can be crosslinked,
when high heat resistance is desirable. The crosslinking can be
carried out by compounding a chemical crosslinking agent, but may
also be carried out by radiation. For example, ultraviolet
radiation, electron beam radiation, and the like, can be
employed.
[0038] A particularly preferred resin composition for the electric
wire covering is one that contains from about 60 to about 97 parts
by weight (preferably from about 70 to about 90 parts by weight) of
a polypropylene polymer, from about 3 to about 40 parts by weight
(preferably from about 10 to about 30 parts by weight) of a polymer
modified with from about 0.1 to about 10% by weight of a monomer
that contains an acid anhydride group, and from about 30 to about
200 parts by weight (preferably from about 50 to about 160 parts by
weight) of a metal hydroxide based on 100 parts by weight of the
polymers.
[0039] Exemplary polymers modified with a monomer that contains an
acid anhydride group include acid anhydride-modified ethylene-vinyl
acetate copolymers, acid anhydride-modified ethylene-ethyl acrylate
copolymers, acid anhydride-modified ethylene-propylene rubbers,
acid anhydride-modified low density polyethylenes, acid
anhydride-modified linear low density polyethylenes, acid
anhydride-modified poly(propylene-ethylene/propylene) copolymers,
acid anhydride-modified styrene-butadiene rubbers, acid
anhydride-modified hydrogenated styrene-butadiene rubbers, acid
anhydride-modified styrene-ethylene/butadiene rubbers, acid
anhydride-modified hydrogenated styrene-ethylene/butadiene rubbers,
and the like.
[0040] The resin composition can be applied to an electrical
conductor to form an insulating covering by any known or later
developed method. In particular, the resin composition can be
applied to a conductor by extrusion. Preferably, the conductor is
covered with the composition to a thickness of from about 0.15 mm
to about 0.35 mm, more preferably from about 0.2 mm to about 0.3
mm. If the coating thickness is less than about 0.2 mm, the covered
wire may have reduced wear resistance, but may be satisfactory for
some purposes. If the coating thickness is more than about 0.3 mm,
the covered wire may have reduced flexibility, but may be
satisfactory for some purposes.
EXAMPLES
[0041] This invention is illustrated by the following examples,
which are merely for the purpose of illustration and are not to be
regarded as limiting the scope of the invention, or the manner in
which it may be practiced.
[0042] In each of the Examples and Comparative Examples below, the
components were continuously mixed and kneaded as follows. The two
resin components and the metal hydroxide were fed simultaneously
into the input hopper of a twin-shaft extruder having an electrical
heating jacket. This extruder was employed to knead the components
together. The extruder temperature (inner surface) was 200.degree.
C. at entry, rising to 250.degree. C. at exit. At the exit end
there was an extrusion head for forming strands from the mixed
composition. The extrusion head was maintained at a temperature of
260.degree. C. The resulting strands were passed through a water
bath to a pelletizer, to form pellets. The pellets were used to
make wire covering, as described below.
Example 1
[0043] 80 parts by weight of a block polymer PP which is a
propylene-ethylene block copolymer having more than 50 wt. %
propylene (POLYPRO RB610A manufactured by Tokuyama Corporation;
melt flow rate (MFR) at 230.degree. C. with a load of 2.16 kg=0.5
g/10 min.), 20 parts by weight of MAH-SEBS (TUFTEC M1913
manufactured by Asahi Kasei Corporation; a styrene-based elastomer
obtained by hydrogenating the double bonds of a styrene-butadiene
block copolymer to saturation and modifying the copolymer with
maleic anhydride) and 90 parts by weight of magnesium hydroxide
(untreated) were kneaded with a twin-screw extruder at 250.degree.
C. A micrograph of the composition obtained is shown in FIG. 1.
[0044] The resin composition of Example 1 was photographed with a
transmission electron microscope (TEM) (model H-800 manufactured by
HITACHI). The photograph was taken at an acceleration voltage of
100 KV. First, the sample was cut to a thickness of about 10 .mu.m
by a microtome for an electron microscope, and the cut sample was
dyed with ruthenic acid (2% aqueous solution) for 2 hours. Then,
the dyed sample was mounted in an epoxy resin, and the TEM was
employed using an ultra thin intercept method.
[0045] In FIG. 1, the approximately hexagonal particles that are
situated at the central part of the picture and the surrounding
narrow long particles are the particles of magnesium hydroxide, the
dense portion at the periphery of the respective particles is the
first polymer (hydrogenated styrene-butadiene elastomer modified
with an acid anhydride) which coats the particles, and the space
between the particles is the continuous phase of the second polymer
(polypropylene).
[0046] As can be seen in FIG. 1, the filler particles hardly
coagulate, and are finely dispersed in the continuous phase of the
second polymer.
[0047] The resin composition of this Example provides very
satisfactory results when used as a covering for an electrical
wire.
Comparative Example 1
[0048] A composition was prepared in the manner described in
Example 1, except that an unmodified styrene-based elastomer was
used, which was obtained by hydrogenating the double bonds of SEBS
(TUFTEC H1041 manufactured by Asahi Kasei Corporation; a
styrene-butadiene block copolymer) to saturation, in place of
MAH-SEBS. The structure of the composition is shown in the
micrograph of FIG. 2.
[0049] Comparison of FIGS. 1 and 2 shows that the styrene-based
polymer modified by unsaturated carboxylic acid, by reason of its
affinity for the magnesium hydroxide filler particles, forms a
structure in the mixture in which styrene-based polymer surrounds
the filler particles preferentially. This arrangement is
advantageous for obtaining properties that are desirable in
compositions used in wire covering.
Examples 2 to 41 and Comparative Examples 2 to 5
[0050] The components shown in Tables 1 to 8 were mixed at the
amounts shown, and kneaded by a twin-screw extruder at 250.degree.
C.
[0051] The resin compositions were obtained by extrusion-molding to
a coating thickness of 0.28 mm around a twisted wire conductor
having 0.5 mm.sup.2 cross-section (composed of 7 copper soft wires
having a diameter of 0.32 mm). Die nipples having diameters of 1.40
mm and 0.88 mm were used for extrusion molding. The extrusion
temperature was 210.degree. C. to 230.degree. C. for the die and
200.degree. C. to 240.degree. C. for the cylinder, and the
extrusion molding was carried out at a linear velocity of 50
m/min.
[0052] The flame resistance, tensile strength/elongation, and wear
resistance of the coated electric wires obtained in Examples 2 to
41 and Comparative Examples 2 to 5 were measured in accordance with
JASO (Japan Automobile Standards Organization) D 611-94. The test
methods are described below.
[0053] To test the flame resistance, a test piece was made by
cutting the coated electric wire to a length of 300 mm. Then, the
test piece was put into a test box made of iron, and horizontally
supported. Using a Bunsen burner having a caliber of 10 mm, the
edge of the flame was applied to the lower side of the central
portion of the test piece for 30 seconds so that it began to
combust, and the time of residual flaming after removal of the
flame was measured. When the time of residual flame was 15 seconds
or less, the sample was regarded as passing, and when the time of
residual flame exceeded 15 seconds, the sample was regarded as
failing.
[0054] The wear resistance was measured by a blade reciprocating
method. A test piece was made by cutting the coated electric wire
to a length of 750 mm. A blade was reciprocated over a length of 10
mm in the axial direction on the surface of the coating material of
the test piece. The test piece was fixed on a stand at room
temperature (25.degree. C.), and the coating material was worn. The
number of reciprocating cycles until the blade reached the
conductor was measured when the blade was reciprocated at a load of
7N and a speed of 50 cycles per minute.
[0055] Then, the test piece was moved by 100 mm, rotated by 90
degrees in a clockwise direction, and the above-described procedure
was repeated. The procedure was repeated three times for each test
piece, and those for which the minimum value was 150 cycles or more
were regarded as passing.
[0056] A test piece (a tubular article of only the wire covering)
was made by cutting the coated electric wire to a length of 150 mm
and removing its conductor. Then, mark lines were aligned to a
central portion. Then, with both ends of the test piece installed
in the chucks of a tensile tester at room temperature
(23.+-.5.degree. C.), the test piece was stretched at a tensile
speed of 200 mm/min., and the load at breaking of the test piece
and the distance between the mark lines at break were measured. A
sample having a tensile strength of 15.7 MPa or more and an
elongation of 125% or more was regarded as passing.
[0057] Flexibility was evaluated by touch when the electric wire
was bent.
[0058] Processability was evaluated by the presence or absence of
whisker formation when the end of the electric wire was peeled.
Those having no whiskers were regarded as passing.
[0059] The results are shown in Tables 1 to 8. The amounts of
components in the Tables are in units of "parts by weight."
1 TABLE 1 E2 E3 E4 E5 E6 CE2 Block copolymer PP.sup.1 60 97 80 90
80 100 MAH-EVA.sup.2 40 3 20 10 20 -- Magnesium hydroxide A.sup.3
70 90 -- -- 90 80 Magnesium hydroxide B.sup.4 -- -- 30 200 -- --
Antioxidant.sup.5 1 1 1 1 1 1 Total 171 191 131 301 191 181 Tensile
elongation (%) >500 >500 >500 180 >500 >500 Tensile
strength (MPa) 26 34 36 21 35 34 Flame-retardance Pass Pass Pass
Pass Pass Pass Wear resistance (cycle) 300 1200 750 200 600 3000
Flexibility Good Good Good Good Good Bad Processability Pass Pass
Pass Pass Pass Reject In Table 1: "E" denotes Example and "CE"
denotes Comparative Example. .sup.1Block polymer PP: a
propylene-ethylene block copolymer; POLYPRO RB610A, manufactured by
Tokuyama Corporation; melt flow rate (MFR) at 230.degree. C. with a
load of 2.16 kg = 0.5 g/10 min; propylene content is above 50% by
weight. .sup.2MAH-EVA: an ethylene-vinyl acetate copolymer modified
with maleic anhydride; HPR VR103, manufactured by Mitsui DuPont
Chemical Co., Ltd.; density = 0.96; Shore A hardness 60; MFR at
190.degree. C. with a load of 2.16 kg = 8 g/10 min. .sup.3Magnesium
hydroxide A: magnesium hydroxide treated with a vinyl silane
coupling agent; manufactured by Kyowa Chemicals Co., Ltd.; average
particle diameter = 1.0 .mu.m. .sup.4Magnesium hydroxide B:
magnesium hydroxide untreated; manufactured by Kyowa Chemicals Co.,
Ltd.; average particle diameter = 1.0 .mu.m. .sup.5Antioxidant: a
hindered phenol-based antioxidant; TOMINOX TT, manufactured by
Yoshitomi Fine Chemicals, Ltd.
[0060]
2 TABLE 2 E7 E8 E9 E10 E11 CE2 Block copolymer PP.sup.1 60 97 80 90
80 100 MAH-EEA.sup.6 40 3 20 10 20 -- Magnesium hydroxide A.sup.3
70 90 -- -- 90 80 Magnesium hydroxide B.sup.4 -- -- 30 200 -- --
Antioxidant.sup.5 1 1 1 1 1 1 Total 171 191 131 301 191 181 Tensile
elongation (%) >500 >500 >500 180 >500 >500 Tensile
strength (MPa) 23 27 30 19 32 34 Flame-retardance Pass Pass Pass
Pass Pass Pass Wear resistance (cycle) 280 1100 650 200 500 500
Flexibility Good Good Good Good Good Bad Processability Pass Pass
Pass Pass Pass Reject In Table 2: "E" denotes Example and "CE"
denotes Comparative Example. .sup.1,3-5See Table 1. .sup.6MAH-EEA:
an ethylene-ethyl acrylate copolymer modified with maleic
anhydride; HPR AR201, manufactured by Mitsui DuPont Chemical Co.,
Ltd.; density = 0.94; Shore A hardness 51; MFR at 190.degree. C.
with a load of 2.16 kg = 7 g/10 min.
[0061]
3 TABLE 3 E12 E13 E14 E15 E16 CE3 Block copolymer PP.sup.1 60 97 80
90 80 80 MAH-EPR.sup.7 40 3 20 10 20 -- EPR.sup.8 -- -- -- -- -- 20
Magnesium hydroxide A.sup.3 70 90 -- -- 90 90 Magnesium hydroxide
B.sup.4 -- -- 30 200 -- -- Antioxidant.sup.5 1 1 1 1 1 1 Total 171
191 131 301 191 191 Tensile elongation (%) >500 >500 >500
160 >500 >500 Tensile strength (MPa) 24 27 25 19 28 2
Flame-retardance Pass Pass Pass Pass Pass Pass Wear resistance
(cycle) 220 900 700 200 400. 70 Flexibility Good Good Good Good
Good Bad Processability Pass Pass Pass Pass Pass Reject In Table 3:
"E" denotes Example and "CE" denotes Comparative Example.
.sup.1,3-5See Table 1. .sup.7MAH-EPR: an ethylene-propylene rubber
modified with maleic anhydride; T7741P, manufactured by JSR
Corporation; density = 0.86; Shore A hardness 57; MFR at
190.degree. C. with a load of 2.16 kg = 0.9 g/10 min. .sup.8EPR: an
ethylene-propylene rubber; EP02P, manufactured by JSR Corporation;
density 0.86; Shore A hardness 55; MFR at 190.degree. C. with a
load of 2.16 kg 3.2 g/10 min.
[0062]
4 TABLE 4 E17 E18 E19 E20 E21 CE2 Block copolymer PP.sup.1 60 97 80
90 80 100 MAH-LDPE.sup.9 40 3 20 10 20 -- Magnesium hydroxide
A.sup.3 70 90 -- -- 90 80 Magnesium hydroxide B.sup.4 -- -- 30 200
-- -- Antioxidant.sup.5 1 1 1 1 1 1 Total 171 191 131 301 191 181
Tensile elongation (%) >500 >500 >500 180 >500 >500
Tensile strength (MPa) 25 30 31 18 25 34 Flame-retardance Pass Pass
Pass Pass Pass Pass Wear resistance (cycle) 200 1250 700 250 600
3000 Flexibility Good Good Good Good Good Bad Processability Pass
Pass Pass Pass Pass Reject In Table 4: "E" denotes Example and "CE"
denotes Comparative Example. .sup.1,3-5See Table 1. .sup.9MAH-LDPE:
a low density polyethylene modified with maleic anhydride; ADOTEX
ER510E, manufactured by Japan Polyolefin Co., Ltd.; density = 0.91;
Shore D hardness 47; MFR at 230.degree. C. with a load of 2.16 kg =
2.2 g/10 min.
[0063]
5 TABLE 5 E22 E23 E24 E25 E26 CE2 Block copolymer PP.sup.1 60 97 80
90 80 100 MAH-LLDPE.sup.10 40 3 20 10 20 -- Magnesium hydroxide
A.sup.3 70 90 -- -- 90 80 Magnesium hydroxide B.sup.4 -- -- 30 200
-- -- Antioxidant.sup.5 1 1 1 1 1 1 Total 171 191 131 301 191 181
Tensile elongation (%) >500 >500 >500 60 >500 >500
Tensile strength (MPa) 27 32 33 20 26 34 Flame-retardance Pass Pass
Pass Pass Pass Pass Wear resistance (cycle) 240 1300 750 300 700
3000 Flexibility Good Good Good Good Good Bad Processability Pass
Pass Pass Pass Pass Reject In Table 5: "E" denotes Example and "CE"
denotes Comparative Example. .sup.1,3-5See Table 1.
.sup.10MAH-LLDPE: a linear low density polyethylene modified with
maleic anhydride; ADOTEX ER621F, manufactured by Japan Polyolefin
Co., Ltd.; density = 0.91; Shore D hardness 45; MFR at 230.degree.
C. with a load of 2.16 kg = 3.5 g/10 min.
[0064]
6 TABLE 6 E27 E28 E29 E30 E31 CE2 Block copolymer PP.sup.1 60 97 80
90 80 100 MAH-PP/EPR.sup.11 40 3 20 10 20 -- Magnesium hydroxide
A.sup.3 70 90 -- -- 90 80 Magnesium hydroxide B.sup.4 -- -- 30 200
-- Antioxidant.sup.5 1 1 1 1 1 1 Total 171 191 131 301 191 181
Tensile elongation (%) >500 >500 >500 200 >500 >500
Tensile strength (MPa) 23 27 26 25 30 34 Flame-retardance Pass Pass
Pass Pass Pass Pass Wear resistance (cycle) 200 1200 1800 210 1800
3000 Flexibility Good Good Good Good Good Bad Processability Pass
Pass Pass Pass Pass Reject In Table 6: "E" denotes Example and "CE"
denotes Comparative Example. .sup.1,3-5See Table 1.
.sup.11MAH-PP/EPR: a polymer of PP and EP; TOKUYAMA 310J,
manufactured by Tokuyama Corporation; density = 0.88; Shore D
hardness 28; MFR at 230.degree. C. with a load of 2.16 kg = 1.5
g/10 min.; modified with 1% by mass of maleic anhydride.
[0065]
7 TABLE 7 E32 E33 E34 E35 E36 CE4 Block copolymer PP.sup.1 60 97 80
90 80 80 MAH-HSBR.sup.12 40 3 20 10 20 -- HSBR.sup.13 -- -- -- --
-- 20 Magnesium hydroxide A.sup.3 70 90 -- -- 90 80 Magnesium
hydroxide B.sup.4 -- -- 30 200 -- -- Antioxidant.sup.5 1 1 1 1 1 1
Total 171 191 131 301 191 191 Tensile elongation (%) >300
>500 >500 170 >500 >500 Tensile strength (MPa) 27 30 31
24 30 34 Flame-retardance Pass Pass Pass Pass Pass Pass Wear
resistance (cycle) 400 1500 2500 260 1800 110 Flexibility Good Good
Good Good Good Bad Processability Pass Pass Pass Pass Pass Reject
In Table 7: "E" denotes Example and "CE" denotes Comparative
Example. .sup.1,3-5See Table 1. .sup.12MAH-HSBR: a hydrogenated
styrene-butadiene rubber; DYNARON 1320P, manufactured by JSR
Corporation; density = 0.89; Shore A hardness 41; MFR at
230.degree. C. with a load of 2.16 kg = 3.5 g/10 min.; modified
with 1% by weight of maleic anhydride. .sup.13HSBR: a hydrogenated
styrene-butadiene rubber; DYNARON 1320P manufactured by JSR
Corporation; density = 0.89; MFR at 230.degree. C. with a load of
2.16 kg = 3.5 g/10 min.
[0066]
8 TABLE 8 E37 E38 E39 E40 E41 CE5 Block copolymer PP.sup.1 60 97 80
90 80 80 MAH-SEPS.sup.14 40 3 20 10 20 -- SBPS.sup.15 -- -- -- --
-- 20 Magnesium hydroxide A.sup.3 70 90 -- -- 90 80 Magnesium
hydroxide B.sup.4 -- -- 30 200 -- -- Antioxidant.sup.5 1 1 1 1 1 1
Total 171 191 131 301 191 191 Tensile elongation (%) 250 >500
>500 170 >500 700 Tensile strength (MPa) 25 28 26 27 28 27
Flame-retardance Pass Pass Pass Pass Pass Pass Wear resistance
(cycle) 400 1300 1200 260 1700 90 Flexibility Good Good Good Good
Good Good Processability Pass Pass Pass Pass Pass Pass In Table 8:
"E" denotes Example and "CE" denotes Comparative Example.
.sup.1,3-5See Table 1. .sup.14MAH-SEPS: a hydrogenated
styrene-isoprene block copolymer; SEPTON 2043, manufactured by
Kuraray Co., Ltd.; density = 0.89; Shore A hardness 38; MFR at
230.degree. C. with a load of 2.16 kg = 4 g/10 min.; modified with
1% by weight of maleic anhydride. .sup.15SEPS: a hydrogenated
styrene-isoprene copolymer; density = 0.89; MFR at 230.degree. C.
with a load of 2.16 kg = 4 g/10 min.
Examples 42 to 51
[0067] In Examples 42 to 46 of this invention, the following
components were kneaded at the ratios shown in Table 9 to prepare
resin compositions
[0068] Using an extrusion molding machine, each composition was
applied at a thickness of 0.28 mm to a conductor (seven soft copper
wires twisted together and circularly compressed to give a smooth
peripheral surface) having a cross-sectional area of 0.5 mm.sup.2
to prepare an electrical wire. The die nipples used in the
extrusion molding had diameters of 1.40 mm and 0.88 mm. The
extrusion temperature of the die was 210.degree. C. to 230.degree.
C. The extrusion temperature of the cylinder was 200.degree. C. to
240.degree. C. The linear speed was 50 m/minute.
[0069] In Examples 47 to 51 of the invention, the same components
as used in Examples 42 to 46 were kneaded at the ratios shown in
Table 3 to prepare compositions selected to be suitable for use in
an electrical wire having a small diameter. Using an extrusion
molding machine, the composition was applied at a thickness of 0.20
mm to a conductor (seven soft copper wires twisted together and
circularly compressed to give a smooth peripheral surface) having a
cross-sectional area of 0.13 mm.sup.2 to prepare the covered wire.
The die nipples used in the extrusion molding had diameters of 0.50
mm and 0.90 mm. The extrusion temperature of the die was
210.degree. C. to 230.degree. C. The extrusion temperature of the
cylinder was 200.degree. C. to 240.degree. C. The linear speed was
50 m/minute.
[0070] The covered electrical wires of the examples were tested to
examine flame resistance (fire resistance), wear resistance,
tensile strength, tensile elongation, flexibility, and
processability, as described below.
[0071] A flame resistance test was conducted in accordance with
JASO D611-94 of Japanese Automobile Standards Organization, as
described above.
[0072] In accordance with JASO D611-94, a wear resistance test was
conducted as described above. In the case of Examples 42 to 46,
specimens for which the blade reciprocated more than 150 times were
regarded as successful. In the case of Examples 47 to 51, specimens
for which the blade reciprocated more than 100 times were regarded
as successful.
[0073] In accordance with JASO D611-94, tensile strength and
tensile elongation tests were conducted as described above.
[0074] Flexibility was evaluated by touch. Specimens which gave a
good feeling when they were bent by hand were regarded as
successful.
[0075] To test processability, part of the resin composition
disposed at the end of each covered wire was peeled off from the
conductor to check whether a whisker was formed. Specimens on which
no whisker was formed were regarded as successful.
[0076] Tables 9 and 10 show the components (in parts by weight) of
each resin composition and the results obtained for each electrical
wire.
9 TABLE 9 E42 E43 E44 E45 E46 Block copolymer PP.sup.1 60 97 80 90
80 MAH-SEBS.sup.16 40 3 20 10 20 Magnesium hydroxide A.sup.3 70 90
-- -- 90 Magnesium hydroxide B.sup.4 -- -- 50 200 --
Antioxidant.sup.5 1 1 1 1 1 Total (parts by weight) 171 191 151 301
191 Fire resistance Pass Pass Pass Pass Pass Wear resistance
(reciprocation 500 1800 4000 300 2000 number of blade) Tensile
strength (MPa) 28 31 34 23 33 Tensile elongation (%) 200 420 520
160 320 Flexibility Good Good Good Good Good Processability Pass
Pass Pass Pass Pass In Table 9: "E" denotes Example. .sup.1,3-5See
Table 1. .sup.16MAH-SEBS: maleic anhydride-modified hydrogenated
styrene-butadiene-styrene copolymer; TUFTEC M1913 manufactured by
Asahi Chemical Co., Ltd.
[0077]
10 TABLE 10 E47 E48 E49 E50 E51 Block copolymer PP.sup.1 95 90 80
65 80 MAH-SEBS.sup.16 5 10 20 35 20 Magnesium hydroxide B.sup.4 120
150 200 160 100 Antioxidant.sup.5 1 1 1 1 1 Total (parts by weight)
221 251 301 261 201 Fire resistance Pass Pass Pass Pass Pass Wear
resistance (reciprocation Over Over Over 180 Over number of blade)
500 500 500 500 Tensile strength (MPa) 32 30 32 30 29 Tensile
elongation (%) 260 220 210 250 265 Flexibility Good Good Good Good
Good Processability Pass Pass Pass Pass Pass In Table 10: "E"
denotes Example. .sup.1,4,5See Table 1. .sup.16See Table 9.
[0078] The coated wires of each of Examples 42 to 51 of this
invention were satisfactory in fire resistance, wear resistance,
tensile strength, tensile elongation, flexibility and
processability. In particular, the resin compositions of each of
Examples 44 and 46, shown in Table 9, had desirable mechanical
strength properties, such as wear resistance, tensile strength and
tensile elongation, and a good balance between these
characteristics. Each of these compositions contained 70 to 90
parts by weight of the propylene resin and 10 to 30 parts by weight
of the styrene thermoplastic elastomer modified with the
unsaturated carboxylic acid or its derivative and 50 to 150 parts
by weight of the metal hydroxide per 100 parts by weight of the
polymers.
[0079] While the invention has been described in conjunction with
the exemplary embodiments described above, many equivalent
modifications and variations will be apparent to those skilled in
the art when given this disclosure. Accordingly, the exemplary
embodiments of the invention set forth above are considered to be
illustrative and not limiting. Various changes to the described
embodiments may be made without departing from the spirit and scope
of the invention.
* * * * *