Product Introductions

Long-Lifetime FEPM TOUGHUORO™

1. Introduction
Tetrafluoroethylene propylene rubber（FEPM）is alifetime FEPM with improved heat resistance andsteam resistance by utilizing our proprietary mixing
design technology.

type of fluororubber（FKM）. It is a copolymer oftetrafluoroethylene（TFE）and propylene（P）and hasa different molecular structure compared to ordinary

2. Characteristics of TOUGHUORO™
Compared to our existing FEPM, D0970 and D0890,（VDF）and hexafluoropropene（HFP））.

TOUGHUORO™ is a material with significantly

Table1 shows the molecular structure of FEPM andimproved heat resistance and steam resistance. BelowFKM.

are the various characteristics of TOUGHUORO™.
Table1

Molecular structure of FEPM and FKM

Type

Molecular structure

FEPM２-１）Compression set characteristics properties
Compression set is used as an indicator for heatresistance in sealing material.
Under the same environment, a smaller compression
set means the sealing material can be used favorably

FKM（Copolymer）

for a longer period of time.
Figure1 shows the measurement and calculation
methods for compression set.
In general, compression set of 80% is considered asWith this molecular structure, FEPM has characteristics

sufficient for life expectancy of material used forsuch as superior steam resistance and chemicalsealing1）, but the compression set of TOUGHUORO™

resistance which were weak points for FKM. FEPM isshowed better results than our existing FEPM and it isused as sealing for food and beverages facilities andanticipated to have a 4 - fold longer in air at 200℃ .

sealing for tire vulcanizing devices.
However, with advancements in functionality offacilities and downsizing, the chemicals used for cleaning
the facilities have become higher in temperature andconcentration, and facilities are used in tougher
environments, leading to more demanding properties
for sealing material.
In this article, we will introduce the steam-resistant SS
series and low compression set ZS series ofTOUGHUORO™ that we have developed as a long-

Winter 2019

fluororubber（FKM; copolymer of vinylidene fluoride

Compression Set（%）
InitialheightCross
SectionCompression ratio（%）
Heightafter test

Before test

During test

SpacerCompression Set（%）

Figure1

After test
Spacer（Initial height）−（Height after test）（Initial height）−（Spacer height）

 easurement and calculation methods
Mfor Compression Set
28

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Long-Lifetime FEPM TOUGHUORO™

Figure2 shows the results for compression set in air at
200℃ .

Compression Set（％）

CS＝80％
Seal Limit

4-foldNo bulister

bulister

TOUGHUORO™-SS70

D0970

Figure4 ross section of specimen after Compression Set  
Ctest in steam at 230℃２-3）A
 cid resistance and alkali resistanceproperties
Regarding acid resistance and alkali resistance ofTOUGHUORO™-SS70, it is equivalent or higher thanTime（h）

Figure2Compression Set in air at 200℃

that of D0970. Since heat resistance ofTOUGHUORO™ has improved, it can be used underhigher thermal conditions.
Figure5 shows the results for change in volume after theUnder steam conditions, HNBR and EPDM have beenacid and alkali immersion test.

used conventionally to suppress foaming phenomenon
difficult to use these materials due to their characteristics.
Our newly developed TOUGHUORO™ has improved
mechanical strength as well and even under 230℃

No.36

Test conditions：90℃×168h

called blister 2）, but in conditions over 150℃, it wassteam conditions, no signs of blisters were confirmed,
making it possible to use as a good sealing material.
Figure3 shows the application area in stream ofTOUGHUORO™ and various materials.

Change of volume（％）

Winter 2019２-2）Steam resistance properties

TOUGHUORO™-SS70

TOUGHUORO™

Figure5 C hange in volume of TOUGHUORO™ after acidand alkaline immersion test２-４）W ater-glycol based flame-retardant
hydraulic oil resistance properties
Resistance of TOUGHUORO™-SS90 to water-glycol
f lame-retardant hydraulic oil （HYDOL HAW,manufactured by MORESCO）is equivalent or higher
Figure3

Applicable area in steam ofTOUGHUORO™ and various materials

than D0890.
The pass or fail judgment was made by stretchchange ratio and volume change ratio（judgment

Figure4 shows a cross-section of the sample after

criteria: within ±50% change in elongation, within

compression set test in steam at 230℃ .

+10% change in volume were judged as ○ , those that29

Product Introductions

slightly exceeded the criteria were judged as △, those that

Test conditions：120℃×1000h25%Compression、φ29×12.5h

clearly exceeded the criteria were judged as ×3））.
Table2 shows the resistance of TOUGHUORO™ toTable2Compression Set（％）

water-glycol based flame-retardant hydraulic oil.
Resistance of TOUGHUORO™ to water-glycol
based flame-retardant hydraulic oil
TOUGHUORO™-SS90

D0890

Change inElongation○○

Change inVolume○○Test conditions：120℃×1000h

TOUGHUORO™-SS90

Figure6

It was confirmed that TOUGHUORO™-SS90 issuperior in regards to compression set and it is ompression Set of  TOUGHUORO™ to Cwater-glycol based fire-retardant hydraulic oil

anticipated to enable use for a longer period. Figure6
shows the compression set after the water-glycol
based flame-retardant hydraulic oil test.

Material characteristics of TOUGHUORO™
Developmental products
Low compression set
ZS series

Steam-resistant SS series

Material name
TOUGHUORO™
-SS70

TOUGHUORO™
-SS80

TOUGHUORO™
-SS90

TOUGHUORO™
-ZS80

Hardness（ShoreA）

74

84

90

85

Tensile strength
（MPa）

23.1

24.6

22.8

24.3

Elongation
（%）

190

150

110

120

100% Modulus
（MPa）

8.3

15.2

20.9

19.916191814142018112226272120262719No.36

physical properties

Compression set test_200℃×70h
Compression set（%）
in airCompression set（%）
in steamCompression set test_230℃×70h
Compression set（%）
in airCompression set（%）
in steam

Winter 2019

Table3The values are measured values, not standard values.

30

Long-Lifetime FEPM TOUGHUORO™

２-5）Food Sanitation Act
TOUGHUORO™ is a material conforming to thecriteria designated in the Ministry of Health, Labourand Welfare Notification No. 595 （Dissolutionconditions: Used at temperatures over 100℃）.

Rotary joint seals
３．Tire manufacturing market
Sealing for curing press to car tire
４．Food and beverages market
Sealing for food and beverages facilities
５．Nuclear power market

２-6）Product shape

High-temperature, dynamic seals

TOUGHUORO™ can be manufactured into productswith various cross-section shapes and large-diameterssuch as O-rings（No.4640）, V packing（No.4631）andX-rings（No.4641）.

4. Conclusions
TOUGHUORO™ introduced in this article is a material
that shows its best characteristics in high temperature

Winter 2019No.36２-7）Mechanical propertiessteam conditions. In the future, higher demands may

There are two grades of TOUGHUORO™, the steam

be placed on sealing material, but it is considered that

resistant SS series and the low compression set ZS

this would be able to sufficiently answer thoseseries.

demands.

Table3 shows the physical characteristics andWe would like to continue developing new materials

compression set in 200℃ air/steam for each grade.

and improving existing materials to correspond to therequests of our users.

3. TOUGHUORO™ applications
TOUGHUORO™ has superior heat resistance and5. References

stea m resista nce a nd t he f ollowing uses a re１）T oshio Kawamura: Valqua Review, Vol26, No.6（1982）

considered:２）H irofumi Zushi: Valqua Technology News, No.31

１．Mining market（2016）

Bit seals３）K en Suzuki: Valqua Technology News, No.24（2013）

２．Steel market＊“TOUGHUORO”is a trademark of VALQUA, LTD.

Hirofumi Zushi
Corporate Research and Development Group
Product Development Division31