thProceedings of the 17 Plastic Pipes Conference
PPXVII
September 22-24, 2014, Chicago, Illinois, USA

ADVANCED PE100 GRADE WITH AN EXCELLENT BALANCE BETWEEN DURABILITY AND
PROCESSABILITY
Tomomi Hiramoto
Japan Polyethylene Corporation
Kawasaki, Kanagawa, Japan

Tetsuya Yoshikiyo
Japan Polyethylene Corporation
Kawasaki, Kanagawa, Japan

ABSTRACT
Polyethylene has been used for various pipe applications. In particular the use of PE100 material has been expanding in pressure
pipes for gas and water service. In general, PE100 materials have very high molecular weight component in order to improve theperformance of durability, so they have high viscosity and their processability are usually poor. Responding to increased demand of
PE100 pipes in the market, requirements for the improved production efficiency are growing. To meet those customer needs, wedeveloped a new PE100 grade which has an excellent balance between durability and processability. In PPXIII, we have reported
PE100 grade (NOVATECTM HD HE212W, HLMFR=9g/10min) which has extraordinary resistance to slow crack growth (SCG) ;notch pipe test (NPT) >20,000h, using our Advanced Multi-modal Slurry Loop Process (AMSLP), which has 3 cascade reactors, and ahigh performance catalyst. As a result of further refining on this technology, we have succeeded in developing a new PE100 grade(NOVATECTM HD HE222W) which has the best balance between flowability and SCG resistance. The new PE100 grade whose
HLMFR is 18g/10min shows excellent processability, for example, >10% less extrusion load, >20% less injection pressure and bettersurface finish of injection molded fittings than a conventional one. Moreover, it is possible to mold at lower temperature. Lower
processing temperature decreases the risk of processing defects such as burn particles and die drool, it also contributes to energy
saving. These features are expected to drastically improve production efficiency of both pipe extrusion and fitting injection. Regarding
the durability of the new PE100 grade, it keeps very good SCG resistance level. NPT result of >5,000h determined at our laboratory is
far more superior to the specification in ISO 4427 and ISO 4437. We believe that our new PE100 grade can contribute to the further
growth of plastic pipe industry.

INTRODUCTION
Advantages of polyethylene pipe
Polyethylene (PE) has already established and is expanding its position as a major material for many pipe applications based on its
excellent characteristics such as light weight and flexibility for easy handling and its superior chemical stability. The flexibility of PE
pipe gives it a great ability to follow the ground movement. Even in the Great East Japan Earthquake (magnitude 9.0) that occurred on
March 11, 2011, no damage of PE pipe system (for water supply) was reported in spite of its terrible shock.1 Excellent strength of PE
pipe system to the earthquake is now widely acknowledged in Japan, and PE pipe system is governmentally recommended as one of
the earthquake-resistant pipe systems.
Globally, PE100 market is rapidly expanding based on its reliability for gas and water delivery services, together with the
spreading of larger diameter pipes and reduced cost installation technologies such as no-dig and no-sand method, which is realized by
the successful development of PE100 materials with superior SCG resistance.
Recent needs for PE100 materialWith the growing concerns for environmental issues such as global warming caused by Green House Gas emissions and natural
resources depletion, suitable measures to reduce such environmental impacts are strongly required these days. In that context, needs
for PE100 material that reduce the energy consumption and the loss in pipe and fitting molding process are increasing.
To reduce the energy consumption, or to improve the energy efficiency of the molding, improvement of the flowability of thematerial is necessary. Easier flow material, which means the low viscosity at the molding shear rate, can reduce the motor load,material temperature and material pressure. Low motor load directly leads to the reduction of the energy consumption. Low material

1

Copyright © 2014 by PPCA

temperature reduces the cooling energy and time, so it has the possibility to increase the production speed. And low material
temperature also can contribute to decrease the risk of processing defects such as burn particles and die drool. Low material pressure
can lead to the extended life time of machine and mold. All these improvements mentioned above also lead to production cost
reduction.
Regarding the injection molded fittings, the poor processability of conventional PE100 material has been a big issue. Low
flowability of the material makes the surface finish of the fittings very bad and often causes warpage problems, reducing the design
freedom of the fittings. So, PE100 material with high flowability is now strongly required also from the view point of product qualityof the fittings.
Although we stated the needs to improve the flowability of PE100 material, PE100 material of course must have durability andstrength that are required by the standards (ISO 4437 for gas, ISO 4427 for water).
To keep or further increase reliability for PE100 material, new high flow PE100 material should have far higher values than thoserequired in the standards, not just meeting the requirements. In Table 1, we summarize recent needs for PE100.
Table 1

Recent market needs and requirements for PE100 material

Market Needs
Reliability

Production
efficiency

Material Property(Required)

Expected effects

Sufficient SCG /RCP

Increase of product reliability
Meeting new installation methods (No-sand, No-dig etc.)

Good processability






Energy saving during molding
Loss reduction
Flexibility increase of the fitting design
Life time extension of molding machine and mold

NEW MATERIAL DEVELOPMENT
To meet recent needs for PE100 material, we started the development of new PE100 grade which has an excellent balance between
durability and processability.
Generally, PE100 material for pressure pipe application is bimodal product which consists of 2 components, low density highmolecular weight component (HMWC) and high density low molecular weight component (LMWC). The higher the ratio of HMWC
is to improve strength and durability of the material, the poorer the material flowability becomes. Oppositely, the higher the ratio of
LMWC is, the lower the product durability becomes. For these reasons, it is not easy to increase flowability of PE100 material
keeping its excellent strength and durability.
In our previous study which we reported in PPXⅢ, we mentioned that concentrating co-monomer in HMWC and distributing comonomer evenly within the molecule are two important factors in order to develop excellent durability material2. To realize suchmolecular architecture, we also mentioned our Advanced Multi-modal Slurry Loop Process (AMSLP) and our high performance
catalyst. AMSLP is our original process with 3 cascade reactors and is capable of precise control of each molecular weight component.
And our high performance catalyst has a feature of high co-polymerization ability and even co-monomer distribution in PE molecule.
In order to achieve an excellent balance, we studied more precisely the relationship between molecular architecture and polymer
properties, using AMSLP and our high performance catalyst.
In this study, we used CL/CH and Tβδ/Tδδ/C as indicators to show the state of co-monomer incorporation which affect the
durability of the material. CL/CH indicates the co-monomer concentration ratio of LMWC to HMWC. We measured the C H directly byusing C-13 NMR3. Regarding CL, we calculated the value using CH and co-monomer concentration of the whole polymer. The lower
CL/CH value is, the more the co-monomer is concentrated in the HMWC. Tβδ/Tδδ/C is also calculated from the C-13 NMR spectrum4,
5. As shown in Fig. 1, Tβδ means the number of the successive incorporation of two co-monomers, calculated from the height of 36.0
ppm peak. Tδδ means the number of the isolated co-monomer incorporation, calculated from the height of 38.1 ppm peak. C means
the co-monomer content of the whole polymer. The lower Tβδ/Tδδ/C value is, the more evenly the co-monomer is incorporated in PE
molecular chain.
As a result of further study and refining of the AMSLP technology, we developed a new PE100 grade (NOVATECTM HD
HE222W) which has an excellent balance between durability and processability. Table 2 shows the summery of our study on themolecular architecture. The SCG resistance was estimated with our evaluation method, Accelerated Full Notch Creep Test (FNCT).
The details of this test method are shown in Fig. 2. This test result has a good correlation with notch pipe test (NPT) 6 result measured
according to ISO 13479. Fig. 3 shows the correlation between Accelerated FNCT and NPT.

2

Copyright © 2014 by PPCAIn Table 2, PE-1 is a bi-modal material produced using conventional 2 staged cascade reactor, whose HLMFR is 9g/10min.
NOVATECTM HD HE212W is a PE100 material produced using AMSLP with excellent SCG resistance we previously reported in
PPXⅢ, whose HLMFR is the same as that of PE-1. As shown in Table 2, both CL/CH and Tβδ/Tδδ/C of NOVATECTM HD HE212W
are lower than those of PE-1 , this means that co-monomer of NOVATECTM HD HE212W is more concentrated in HMWC and more
evenly incorporated in PE molecular chain than those of PE-1. We think that this difference is the reason why Accelerated FNCT valueof NOVATECTM HD HE212W (550h) is nearly 8 times higher than that of PE-1 (70h).
In the development of NOVATECTM HD HE222W, we tried to enhance the concentration of co-monomer in HMWC, or tried toreduce the CL/CH value, by optimally adjusting the polymer content, molecular weight and co-monomer content of each of the 3stages. As shown in Table 2, CL/CH value of NOVATECTM HD HE222W (0.08) is the lowest in these three materials. We think that thislow CL/CH makes it possible for NOVATECTM HD HE222W to have high Accelerated FNCT value of 350h which is 5 times higher
than that of PE-1, in spite of high HLMFR (18g/10min) of NOVATECTM HD HE222W which is twice of that of conventional bimodal PE (PE-1).
Table 2

Summary of our molecular architecture study
NOVATECTM HD

NOVATECTM HD

HE212W

HE222W

2-stage polymerization
High performance
catalyst

AMSLPHigh performance
catalyst

AMSLPHigh performance
catalyst

PE-1
Process－

Catalyst－

HLMFR

g/10min9918

Density

kg/m3

950

948

950

Co-monomer-

Hexene-1

Hexene-1

Hexene-1

C (co-monomer concentration)

mol%

0.42

0.55

0.42

CL/CH

-

0.40

0.16

0.07

Tβδ/Tδδ/C

-

0.14

0.09

0.08

Accelerated FNCT

h

70

550

350

a : Tβδ (successive incorporation)b : Tδδ (isolated incorporation)

b

a
PPM
40

Fig. 1

35

30

25

20

15

10

C-13 NMR spectrum

3

Copyright © 2014 by PPCA

Fig. 2

Accelerated FNCT

Fig. 3

Relationship between Accelerated FNCT and NPTEVALUATION RESULTS OF NEW HIGH FLOW PE100 (NOVATECTM

HD HE222W)

We evaluated practical properties required for PE100 material and processability for pipe extrusion and injection molding of
NOVATECTM HD HE222W.
In Table 3, we summarize the evaluation results of this New PE100 grade (NOVATECTM HD HE222W) together with those of
our other commercial PE100 grades. NOVATECTM HD HE212W is also PE100 material produced using AMSLP, whose HLMFR is 9
g/10min and its SCG resistance is the most excellent. PE-A and PE-B are our previous PE100 grades produced using conventional 2
staged cascade reactor. HLMFR of PE-A is 17g/10min, nearly the same level of NOVATECTM HD HE222W. HLMFR of PE-B is 9
g/10min, the same as that of NOVATECTM HD HE212W.
Fig. 4 shows the shear rate dependences of viscosity. These data were measured using capillary rheometer (test temperature :190 degree C, capillary diameter (D) : 1.53mmφ, length (L) : 25.43mm). The melt viscosity of NOVATECTM HD HE222W in highshear region is the lowest among them. These results show that NOVATECTM HD HE222W is an appropriate material for especiallyinjection molding.

4

Copyright © 2014 by PPCA

Accelerated FNCT (specimens were made by press molding) and NPT were performed for estimation of the SCG resistance. It
turned out that NOVATECTM HD HE222W excels the other PE100 materials produced by conventional technology in the SCG
resistance in spite of its highest HLMFR of 18g/10min.
Typical properties of NOVATECTM HD HE222W compared with commercial PE100 materials

Table 3

NOVATECTM HD

NOVATECTM HD

HE222W

HE212W

Commercial
PE-A

Commercial
PE-B

ISO 1133

18

9

17

9

-

ISO 1133

150

180

140

180

Densitykg/m3

ISO 1183

950

948

949

950

Class

－

－

PE100

PE100

PE100

PE100

Process

－

－

AMSLP

AMSLP

2-stagepolymerization

2-stagepolymerization

Notch pipe testh

ISO 13479

3,900*

21,700*2,500 **－

Accelerated FNCT

h

‐

350

550

270

130

Charpy impact strength
at 23 degree C
Charpy impact strength
at -20 degree C

kJ/m2

ISO 179

22

34

20

20

kJ/m2

ISO 179

9

19

9

10

RCP-S4bar

ISO 13477－> 25 *> 16 **－

Co-monomer--

Hexene-1

Hexene-1

Hexene-1

Butene-1

PropertyHLMFR
FRR(21.6/2.16)* determined at EXOVA

Fig. 4

Unit

Methodg/10min** determined at Kiwa Gastec Certification

Shear rate dependence of viscosity at 190 degree C

5

Copyright © 2014 by PPCA

Although HLMFR of NOVATECTM HD HE222W is very high as PE100 material, the value of the NPT is 7 times higher than therequired value (500h) in water and gas pipe application (ISO 44277/44378). This result indicates the balance between the durability
and the flowability of NOVATECTM HD HE222W is excellent. Fig. 5 shows the result of hydrostatic strength measured according toISO 90809. There was no brittle failure at all temperatures until 10,000h. And break time of NOVATECTM HD HE222W at 20 degree
C under 12.4 MPa hoop stress was over 500h. This result shows that NOVATECTM HD HE222W has enough durability as well.
Regarding rapid crack propagation (RCP) properties of NOVATECTM HD HE222W, although we have not yet carried out the test,comparing the Charpy impact strength of NOVATECTM HD HE222W with that of PE-A, we consider that S4 (small-scale steadystate) RCP10 performance of NOVATECTM HD HE222W will be the same level (>16 bar, at 0 degree C) as that of PE-A11.

Fig. 5

Hydrostatic strength data of NOVATECTM HD HE222W : determined at EXOVA

We evaluated the extrusion properties using the pipe extrusion machine. The test was carried out with 45mm screw diameter, 33
L/D Krauss-Maffei pipe molding machine at 200 degree C. Fig. 6 shows the relationship between output and motor current. The motor
current value of NOVATECTM HD HE222W is lower than those of conventional PE100 materials. Fig. 7 shows the relationshipbetween output and molding pressure. The molding pressure value of NOVATECTM HD HE222W at the same output is extremely
small compared with those of conventional PE100 materials. From these results, we think that NOVATECTM HD HE222W could be
extruded at lower temperature compared with other conventional PE100 materials due to its superior high flowability. As the merits ofmolding at low temperature, reduction of extrusion defects such as burn particles and die drool, and increase of production rate byshortening cooling period could be expected.

Fig. 6

Processability data-1: relationship between output and motor-current

6

Copyright © 2014 by PPCA

nFig. 7

Processability data-2: relationship between output and material pressure

We evaluated the processability for injection molding by the spiral flow test. The data of this test are shown as the flow length atrespective injection temperature. We used FANUC injection molding machine and the Archimedean spiral mold (10mm width, 2mm
thickness, 2,000mm maximum length, mold temperature at 40 degree C). Fig. 8 shows the spiral flow test specimen. The results areshown in Fig. 9. The spiral flow length of NOVATECTM HD HE222W at 230 degree C is 30% longer than that of the NOVATECTM
HD HE212W whose HLMFR is 9g/10min, and 10% longer than that of PE-A whose HLMFR is 17g/10min. Furthermore, the lengthof NOVATECTM HD HE222W at 210 degree C is the same as or longer than that of the commercial PE-A at 230 degree C. From theseresults, we think that NOVATECTM HD HE222W could reduce cycle time and defects rate through lower processing temperature.
Furthermore it is expected that complicated shape fittings which was not able to be designed by the conventional PE100 materials
could be realized by NOVATECTM HD HE222W.

Fig. 8Spiral flow specimen

Fig. 9Processability data-3: relationship between injection pressure and spiral flow length7

Copyright © 2014 by PPCA

Fig.10 shows the surface of the injection molded flat plate (2mm thickness) made from NOVATECTM HD HE222W and PE-B
(HLMFR 9g/10min). In case of NOVATECTM HD HE222W, flow mark does not appear on the surface. This result suggests that
NOVATECTM HD HE222W could give better surface finish of fittings than conventional PE100 material.
NOVATECTM HD HE222W

Fig. 10

Commercial PE-B

Comparison of injection molded plate surface

CONCLUSION
By precise control of molecular architecture using AMSLP, we succeeded to develop new high flow PE100 material(NOVATECTM HD HE222W) with excellent balance between durability and processability. In spite of its high HLMFR of 18g/10min,
it has the durability far exceeding the requirements of ISO 4427/4437, and also can exceed the property requirements defined byPE100+ association.
In Table 4, we summarize the effects and merits gained from using NOVATECTM HE222W.
We hope that NOVATECTM HD HE222W will play a part to improve the production efficiency of PE pipe industry and contributeto the establishment of sustainable society.
Expected effects and merits by NOVATECTM HD HE222W
Injection molding
Extrusion molding
Improved effects
Improved effects○ Reduction of material temperature○ Reduction of material temperature○ Reduction of motor load
○ Reduction of injection pressure○ Reduction of material pressure○ Increase in the flow length○ Increase of through-put○ Improvement of surface finish

Table 4

Merits○ Energy saving○ Defects reduction by low-temperature molding○ Increase in production rate
○ Production cost reduction

Merits○ Energy saving○ Defects reduction by low-temperature molding○ Increase in production rate
○ Increase of design freedom of fittings○ Extended life of machine and mold
○ Production cost reduction

8

Copyright © 2014 by PPCA

REFERENCES
1. Damage investigation 4th report of water service in the Great East Japan Earthquake on March 11, 2011,Japan Polyethylene
Piping System & Integrated Technology Association for Water Supply (POLITEC), 2013
2. T. Yoshikiyo, T. Hattori, “High performance PE100 Material with extraordinary resistance to Slow Crack Growth”, Plastic
Pipes Conference13, Washington, October, 2006
3. X. Lu, N. Ishikawa and N. Brown, J. Polym. Sci., 34, 1809, 1996
4. E. T. Hsieh and J. C. Randal, Macromolecules, 15, 353, 1982
5. E. T. Hsieh and J. C. Randal, Macromolecules, 15, 1402, 1982
6. ISO 13479, Polyolefin pipes for the conveyance of fluids – Determination of resistance to crack propagation – Test method
for slow crack growth on notched pipes
7. ISO 4427, Polyethylene (PE) pipes for water supply – Specifications
8. ISO 4437, Buried polyethylene (PE) pipes for the supply of gaseous fuels – Metric series – Specifications
9. ISO 9080, Plastics piping and ducting systems – Determination of long-term hydrostatic strength of thermoplastics
materials in pipe form by extrapolation
10. ISO 13477, Thermoplastics pipes for the conveyance of fluids - Determination of resistance to rapid crack propagation(RCP) - Small-scale steady-state test (S4 test)
11. T. Piel, E. Zinoecker, F. Mitter, S. Simon, “Fast small scale method to predict materials resistance to rapid crack
propagation” , Plastic Pipes Conference16, Barcelona, September, 20129

Copyright © 2014 by PPCA

ANNEX A
PE 100+ Association required quality of materials
Property

Test Method

PE 100+ Association requirements

Creep Rupture Strength

Pressure test at20°C and 12.4 MPa≧200（h）

Stress Crack Resistance

Pipe notch test at 80°C and 9.2 bar≧500（h）

Resistance to Rapid Crack
Propagation

S4 Test at 0°C

Pc≧10 bar

10

Copyright © 2014 by PPCA