Development of Environment-Friendly Cable "Eco-Ace"by Tomoyuki Suzuki *, Tetsuo Matsumoto *, Eiji Shiramatsu *,Shingo Ooya *2, Osamu Kawasaki *2, Toyokazu Hisatsune *2,
Yoshihiro Maeda *3 and Kunio Iwasaki *3

In recent years, depletion of ozone layer, global warming, environmental pollution, and other environmental problems have been aggravated, and have been
greatly attracting public attention. As a result, awareness to environmental preservation has
increased and countermeasures have begun to be taken at all levels.
We at Furukawa Electric give consideration to preservation of earth environment, and aim atrealizing a society which enables sustainable development in conformity to the "Furukawa
Electric Basic Environment Policy". The environment-friendly cable "Eco-Ace" has been developed as a part of it. "Eco-Ace" is a product developed by thoroughly reviewing conventional typecables from the viewpoint of "environment-friendliness". In particular, the product does not affectthe surrounding environment and achieves high safety and excellent recyclability because special
emphasis is placed on using no material containing any substance that may exert load to theenvironment and on using materials that can be recycled. In this report, discussion will be madeon the development of low-voltage and high-voltage electric wires and cables, and their accessories of, in particular, power and control systems in the product group of environment-friendly
cable "Eco-Ace".

ABSTRACT1.

INTRODUCTION

As a negative side of the advancement of modern civilization, aggravated environmental problems such as depletion of ozone layer, global warming, environmental pollution, etc. have greatly aroused people's concern. It has
been pointed out that the orientation to mass production
and mass consumption which is intensified as the civilization and science advance gives rise to energy extravagance, resource impoverishment, etc., and endangers the"sustainable development" of the society. With these on
the background, in recent years, increased awareness tothe environment is observed at all levels of the world,country, company, civic organization, and individual.
The worldwide campaign for taking countermeasuresagainst environmental problems has extended even to
Japan, and resulted in reorganization of laws such as
Waste Disposal and Public Cleansing Law, ElectricAppliance Recycling Law, etc.
For companies, it has already become a social obligation not to pursue expansion of business or profits only as
before but to establish a concept to the environment andto incorporate this concept into the corporate activities andproducts.
*

Development Sec., Chiba Research Lab., R & D Div.
Industrial Engineering Dept., Industrial Cables Div.
*3 Power Distribution Engineering Dept., Power Cable
Accessories Div.
*2

Furukawa Electric carries out corporate activities withpreservation of earth environment taken into account andwith an aim to realize the society that enables sustainable
development in conformity to the "Furukawa Electric Basic
Environment Policy". This report discusses the development of environment-friendly cable "Eco-Ace" as part ofsuch activities.

2.

WHAT IS "ENVIRONMENT-FRIENDLY"
ELECTRIC WIRE AND CABLE?

What is the "environment-friendly" electric wire and cable?
To grasp this, we must first think of the life cycle of electric
wire and cable. To generally summarize, it can be said
that the life cycle of electric wire and cable comprises fourstages: (1) raw material, (2) processing to product, (3)application, and (4) disposal. The influences of this cycleon the environment are consumption of resources, use ofenergy, and discharge of hazardous substance. Of these,with respect to consumption of resources and use of energy, efforts are made to save resources and energy byreviewing the manufacturing process, promoting
increased efficiency, etc. through cycle (1) and (2). For
cycle (3), there would be no significant influence on theenvironment. We thought that it is cycle (4) that attention
must be given to.
Table 1 shows the actual situation 1) of cable covering
material disposal in the cable industry.

85

Table 1 indicates that almost all cables are disposed ofby landfilling. What is concerned about disposal by landfilling is deposition, dissolution, and leaching of low molecular weight components, additives, or decomposed substances by degradation with time in the electric wire andcable materials. If any of these substances exerts load tothe environment, there is a danger of seriously affecting
the surrounding environment. One answer to this is toeliminate the environment load substances in the product.
Table 1 also indicates that the ratio of reutilization ofcable covering material such as insulation and sheath,that is, the recycling ratio, is not high. From the viewpointof effective utilization of resources, recyclability becomes
important. Examples of recycling include thermal recycling
in which heat is utilized, material recycling in which product material is reused, etc. In thermal recycling, it isessential that the material does not generate any harmful
substance when combusted and at the same time generates less smoke. In material recycling, it would be desirable to use thermoplastic materials from the viewpoint ofease of reformability. Thus, recyclable materials shouldmeet the requirements of either type of recycling.
Based on these, we thought that the "environmentfriendly" electric wire and cable should satisfy the following two requirements.

Table 1

3.1 Selection of Material
From the two requirements described above, raw materials to be used for electric wire and cable covering material
were selected.
For the base material that does not exert load to theenvironment, polyolefin-based resin was selected.
The polyolefin-based resin does not contain any harmful
low molecular weight component or heavy metals, anddoes not generate any substance causing problems when
combusted. Table 2 shows components of combustion
product gas of polyethylene (PE), which is one of the polyolefin-based resins. 2) Table 2 indicates that polyethylene
does not generate any harmful gas such as hydrogencyanide or hydrogen chloride.
Because polyolefin-based resin is thermoplastic, it canmeet the material recycling. In addition, when comparedwith halogen containing resin, polyolefin-based resin generates less smoke.
For the electric wire and cable covering material, flame
retardance exceeding a certain level is required. The
flame retardance required for general electric wires is thecapability to self-extinguish within 60 seconds in the flame
retardance test prescribed in JIS C 3005.
There are two techniques for providing flame retardance
to polyolefin-based resin: (1) flame retardance achievedby halogen (addition of halogen-based flame retardant,
halogenation of resin, etc.) and (2) flame retardanceachieved by metal hydroxides. Of these, flame retardanceachieved by halogen is assumed to exert load to the environment because hazardous substances including hydrogen halide is generated at the time of combustion. As
against this, the substances generated when metalhydroxide is heated are water and metal oxides only,
which are assumed to be stable and safe. Consequently,
flame retardance achieved by metal hydroxides exerts low
load to the environment and is suitable for the flame retardant of this product. In addition, the metal hydroxides

Actual situation of cable covering material disposal
in the Japanese cable industry
Leading six cable manufacturers
Disposal

Covering
material

Amountused

Nugget Council
disposal rate

Recycling

Thermal (total of 59 out of
IncinerLandfill
Reuse decompo- 91 companies.
ation
All by landfilling)
sitionRubber

630

50

1

0

0

1208

PVC

6500

290

0

580

0

3358

PE

3700

160

0

130

0

XLPE

1850

220

95

0

10

720

96

710

10

Total

12680

846

5412
816

720
(Unit: t/month)

Table 2

Combination gas of various materials

Generated
gas

PE

PVC

(mg/g)

Nylon
66

Poly-

Poly-

acrylic acryloamide

nitrilePolyurethane

Polyphenylene
sulfide

HCl

-

286

-

-

-

-

-

CO2

738

657

590

796

556

666

1796

CO

210

177

205

157

108

173

161

COS

-

-

-

-

-

-

2.5

SO2

-

-

-

-

-

-

423

N2O

-

-

-

-

-

-

-

NH3

-

-

9.8

17

-

-

-

HCN

-

-

31

18

56

3.3

-

CH4

72

-

40

16

5.9

21

-

C2H4

185

-

94

10

-

43

-

C2H2

34

11

15

8.5

7.4

14

2.1

62.5 69.3

60.7

63.3

37.7

51.4

85.1

Gasification
ratio (%)86

(A) Non-use of material containing substance thatwould exert load to the environment.
(B) Use of material that can be recycled.
Requirement (A) can be met by not using any substance and material which are identified or suspected toexert load to the environment at the present stage.
Requirement (B) can be met by using the substancewhich does not generate substance causing problems at
the time of thermal recycling and is the thermoplastic
material which can meet the material recycling.

3.

DEVELOPMENT OF "ECO-ACE" LOWVOLTAGE ELECTRIC WIRE AND CABLE

Furukawa Review, No. 19. 2000

have effects to suppress the smoke generation rate of thematerial with the metal hydroxides added. Therefore, aflame retardant technique by metal hydroxides is adopted.
Figure 1 shows the relationship between flame retardant
mechanism of metal hydroxide (example is magnesiumhydroxide) and combustion cycle of palstic. 3)
In general, when plastic material is heated, as shown in
Figure 1, the plastic material ignites and combusts
through fusion, then, decomposition and gasification. To
achieve fusion then decomposition and gasification, about
0.4 kJ/g and 0.8 kJ/g heat energies are required, respectively, but once combustion begins, the plastic material
itself emits a great volume of thermal energy (about 46
kJ/g in terms of PE), forms a combustion cycle, and continues combustion even without firing source.
In the flame retardant mechanism by metal hydroxide,
the addition itself of metal hydroxide dilutes combustibles,
as shown in Figure 1. The metal hydroxide decomposesby heating and causes endothermic reactions. During thisdecomposition, water vapor and combustion products areformed. The water vapor dilutes combustible gas and the
combustion products serve as a heat-insulating layer.
These compositely act on in the combustion cycle, anddisplay flame retardant effects.
However, the flame retardant effects of metal hydroxides are small. For example, the heat absorption rate ofmagnesium hydroxide at the time of decomposition is -0.75
kJ/g, far small as compared to the heat generation rate ofpolyolefin-based resin at the time of combustion.
Consequently, in order to provide the flame retardance topolyolefin-based resin, a large volume of metal hydroxidemust be compounded. However, compounding metalhydroxide in a large quantity degrades mechanical properties of the material. Therefore, new compositions weredeveloped with particular attention placed on the balance
between material mechanical properties and flame retardance.
When metal hydroxide is compounded to polyolefinbased resin, phosphorus-based flame retardant is fre-

S=
C s=

Table 3

Dilution of combustible gas
by water vapor
Mg(OH)2 → MgO+H2O – 0.75 kJ/g
Endothermic (dehydration) reaction

Fusion3.2 Cable Characteristics
Table 4 shows the characteristics of "Eco-Ace" low-voltage wire and cable.
The visibility distance S (m) at the time of smoke generation was found by the following formula using the cablesmoke generation rate in conformity to the formula given
by Fire Handbook. 2)

2.7
Cs
1
I0
ln(
)
I
L

Air

Decomposition
andgasification- 8.0 kJ/g

quently used for the flame retardant assistant. However,since the phosphorus-based flame retardant markedly
increases the smoke generation rate, it was determinedunsuited for the development of this product and was notused.
To the cable covering material, additives necessary forsatisfying properties as cable material are compounded inaddition to the flame retardant assistant. For the additives
used for the developed composition, those assumed not
to exert load to the environment were used.
Table 3 shows the properties of the cable covering
material.
Table 3 indicates that the developed material not only
satisfies the properties required for cable covering material but also provides excellent brittle temperature as compared to those of conventional covering materials.
Because the temperature rating becomes 75°C, higher
than 60°C of the conventional case, a continuous current
rating of 1.3 times is achieved (installed at 40°C ambient
temperature, in air), providing a possibility of downsizing.
In addition to this, development was also carried out on
the materials for cable branches as in the case of selection of the cable covering material, and the material which
provides properties equivalent to those of conventional
ones and yet achieves greater safety and higher recyclability was developed.

Properties of covering material for low-voltage EcoAce cables
Unit

Tensile strength

JIS C 3005

MPa

13

Elongation

JIS C 3005%

650

JIS C 3005%

85

JIS C 3005%

93

JIS C 3005

°C

- 50 or lower

JCS 397mg/g

0covering material

Combustion
Tensile strength after aging
90°C×4 days
Thermal energy- 0.4 kJ/g

+46.0 kJ/g
High molecularmaterial

Formation ofcarbonized layer

FiringsourceElongation after aging
90°C×4 days
Brittleness temperature
Amount of acidic
gases evolved
Oxygen index

Figure 1"Eco-Ace"

Standard

Flame retardant mechanism and combustion cycle ofmetal hydroxide

Temperature rating

26

JIS K 7201
°C

75

87

where,Cs: Absorbance coefficient
I: Measured transmittance
I0: Initial transmittance
L: Length of optical path (m)The present developed product not only provides flame
retardance equivalent to that of conventional products but
also generates no harmful substance such as hydrogen
halide.
The smoke generation from the cable is extremely
small, and it is clear that about 16 times visibility distanceis secured as compared to conventional cables. In general, the visibility distance required for evacuation at thetime of fire is said to be about 15 m for the visitor to thebuilding, suggesting high safety of this new product at thetime of fire.

(Ecological Material - polyEthylene insulated polyEthylene
sheathed Control cable) Eco-Ace cable.
Assuming that the materials other than sheath material
are non-flame-retardant and the weight ratio of the flame
retarding agent of the sheath material is 50%, then, theflame retarding agent in the constitutional materials otherthan conductor of the cable accounts for 21% (this varies
with the cable construction, size, and the weight ratio offlame retarding agent in the sheath material).
It is anticipated in this case, that mixing the entire constitutional materials for recycling excluding the conductor
will result in a flame-retardance which is excessively low.
Therefore, investigations were made on the cases when
the new sheath material was mixed with the recycled

3.3

Product Line-ups of "Eco-Ace" Low-voltage Wire
and Cable
Table 5 shows product line-ups of "Eco-Ace" low-voltage
wires and cables.
Photo 1 shows "Eco-Ace" low-voltage wires and cables
and Photo 2 "Eco-Ace" EM-BH branches.
3.4 Recycle of Non-separated Cable Refuse
In the future when the collection system of separated
refuse is organized, which is problematic at present, recycling of cables as a whole including covering materials(sheath and insulation) and auxiliary materials (tape andfilling material) becomes meaningful. Therefore, the following investigation was carried out.
Figure 2 shows the weight ratio of constitutional materials other than conductor for a 600-V EM-CEE 3 x 14 mm2

Table 4

Photo 1

Low-voltage Eco-Ace cable products

Characteristics of low-voltage Eco-Ace cables
Conventional

Items

Standard

Unit Eco-Ace

Flame retardance test

JIS C 3005

Accepted

Accepted

Amount of acidic
gases evolved
Smoke density:transmittancecable

JCS 397mg/g

0250 - 320

IEC 1034

%

92

25

m

97

6

Visibility distanceComputed fromwhen smoke iscable smoke

generated

generation rate

Photo 2

Eco-Ace EM-BH branch

Flame retardant(21%)

Table 5Low-voltage Eco-Ace cable productsType
Low-voltage power cableLow-voltage flat cable
Control and instrumentation cable

88

Insulation(38%)

Cable designation
600 V EM-CE, 600 V EM-CET
600 V EM-EEF
EM-CEE, EM-CEE-S

Insulated electric wire

EM-IE

Fire resistant cable

FT-8-C

Cable with branch

EM-BH

Non-flame
retardant material(79%)

Figure 2

Filling
material(18%)

Sheath(42%)

Tapes (2%)

Weight ratio of constitutional materials other thanconductor for an Eco-Ace cable (600-V EM-CEE 3 x
14 mm2)

Furukawa Review, No. 19. 2000

Table 6

Properties of recycle sheath material
New sheath Recycle

Mixed

Mixed

samplesampleProperties of covering material for high-voltage EcoAce cables
Standard Unit

Eco-AceConventional cable

JEC

25 kV for 1 min:

25 kV for 1 min:3403

Accepted

Accepted

Accepted

Accepted

96

250 - 3000250 - 320

Unit

materialA

B

D.C. voltage test

Tensile strength

MPa

12

13

15

14

on sheathElongation

%

610

630

670

688

Flame

JIS C

retardance test

3005

Tensile strength after
aging 90°C×4 days
Elongation after aging
Oxygen index%

85

sampleTable 7110

A:B = 1:1 A:B = 3:1

90

85
Smoke density

%

101

65

79

93

28

21

24

25

material collected from cables.
First of all, 600-V EM-CEE 3 x 14 mm2 cables were
manufactured. Auxiliary materials such as fillers and tapes
were selected from those for conventional materials thatare polyolefin-based and having a melting point of 140°C
or lower. Then, from the manufactured cables, conductors
were removed, and the remaining materials were crushed.
This is called recycle sample. Then, a material with new
sheath material and crushed product mixed at 1:1 and thatat 3:1 were prepared. These are called mixed samples.
The recycle sample and the mixed sample were kneaded
at 160°C by a pressurizing type kneader followed by forming into a sheet. Table 6 shows the evaluation results ofthe sheet.
As is clear from Table 6, the recycle sample, as such,
had a flame retardance lowered to a level unsuited for theuse as sheath material. In addition, the elongation after
aging greatly lowered. These are attributed to the improper amount of flame retarding agent and antioxidant in therecycle sample. Therefore, it is desirable to use a mixed
sample, and when the cables are recycled in a plurality oftimes, the mixture ratio of new sheath material must be
increased.

4.

DEVELOPMENT OF "ECO-ACE" HIGHVOLTAGE CABLE

4.1 Improved Damage Resistance of Cable
The cables for high-voltage application is likely to be subject to big side pressure on its sheath because the cablemust be installed in conduits, etc. It has been identified
that the cable may be damaged due to the level differenceof conduits if the sheath material developed for the "EcoAce" low-voltage electric wires and cables is used for the
sheath. Consequently, a new covering material has beendeveloped from the viewpoints of --as is the case with thecable for low-voltage application-- (1) the substance thatwould exert load to the environment is not used and (2)the substance can be recycled. Polyolefin-based resin andmetal hydroxide flame retarding agent were used for thematerial which is provided with an improved resistance forabrasion.
When polyolefin-based resin and metal hydroxide flame
retarding agent are compounded, a large amount of metalhydroxide must be compounded as described earlier, andAmount of acidic
gases evolved

ASTM
E662
JCS 397 mg/g

Damage250 kg/m

250 kg/m

resistance test

Accepted

Accepted

this works to lower mechanical properties. The fillers suchas metal hydroxide exist in resin not dissolved but in theform of scattered particulates. When this kind of material
is subjected to mechanical force, shearing frequently
occurs, and this is a cause of lowering mechanical properties. This suggests that an improved adhesion between
resin and metal hydroxide results in improved damage
resistance. Therefore, adhesive polyolefin was compounded to improve the adhesion between resin and metalhydroxide.
4.2 Cable Characteristics
The developed composition was used for the sheath inmanufacturing 6-kV EM-CET 3 x 60 mm 2 (Ecological
Material - Cross-Linked polyEthylene insulated polyEthylene sheathed Triplex type) power cables. Table 7
shows the cable characteristics. Photo 3 shows the sceneof flame retardance test prescribed in JIS C 3005. Figure
3 illustrates the damage resistance test referred to in thetable. This is a test to see damage in the cable when aspecimen cable is placed with a load and pulled on aframe simulating conduit. When no damage is observedon the cable, the cable is accepted. Photo 4 shows thecable after the damage resistance test.
As is clear from Table 7 and Photo 4, the developed
cable provides a satisfactory damage resistance that is
sufficient to pass the 250-kg/m damage resistance test,
which is comparable to conventional cables.
As described above, the "Eco-Ace" high-voltage cablehas been developed, which is environment-friendly and is
free of problem at the time of cable installation.

5.

CONCLUSION

In order to address environmental problems in recent
years, environment-friendly electric wires and cables wereconsidered, and "Eco-Ace" was developed. And the following results were achieved.
(1) Environment-friendly electric wires and cables were
defined as (A) electric wires and cables that do not
use any substance that exerts load to the environ-89

Pulling direction

Load
Cable

Cable

30~50cm

Cable mount

Cable mount
100mm

l

l

80~
100mm
8mm

Cable mountFigure 3

Damage resistance test

Photo 4

Appearance of an cable after damage resistance test

REFERENCES

Photo 3

Flame retardance test (JIS C 3005)

ment and (B) wires and cables that use recyclable
materials; and development of materials for suchcables and wires was carried out.
(2) Using the developed covering material, environmentfriendly and low smoke generation rate "Eco-Ace"low-voltage wires and cables were developed.
(3) "Eco-Ace" high-voltage cables with improved damage
resistance were developed.

1) Ito et al.: "Presentation of the Joint Study on Recycling of Cable
Covering Materials at JECTEC", First Report on Recycling of
Rubber and Plastic Materials, JECTEC, 1994. (in Japanese)
2) Fire Handbook, Edited by Fire Association of Japan, Kyoritsu
Publishing, 1984. (in Japanese)3) Ishii et al.: "Development of Non-halogen Fire-retardant
Cables", Study Group of Electric Wires and Cables, EC93-3,
1993. (in Japanese)4) Suzuki et al.: "Development of Eco-Ace, an Ecological-material
Cable", Study Group of Electric Wires and Cables, EC98-23,
1998. (in Japanese)
Manuscript received on August 3, 1999.

In the future, while supplying environment-friendly electric wires and cables with superb balance achieved inenvironment-friendliness, economy and functionality, we
hope to cooperate with various people concerned to positively grapple with promotion of recycling.

90

Furukawa Review, No. 19. 2000