Technical Papers

Types and Application ofFiller-added PTFE Materials
The features of each filler-added PTFE are described

1. Introduction

below.
◦ Inorganic fillers

benefits including heat resistance, chemical resistance,◦ Glass fiber

insulation, non-stick, and low friction. Its scope of

Glass fiber has little effect on chemical and electricalapplication is broad: it is used in various fields including

properties. Glass fiber-added PTFE has approximately

semiconductor devices, chemical plants, automobiles,

twice the compression creep resistance and approximately

office equipment, and home appliances.

1000 times better abrasion resistance than pure PTFE.

However, PTFE suffers from inadequate abrasion

These features make glass fiber-added PTFE ideal forresistance and creep resistance, which are serious

improving abrasion resistance. The color is white,

disadvantages leading to severe self-damage in thewhich makes it easy to use. However, it might break acase where PTFE is used in sliding parts like shaft

counterpart shaft when used for shaft bearings.

bearings and large deformation in the case where one◦ Graphite

is used in load-bearing parts. The addition of a different

Graphite improves creep resistance and reduces initialmaterial, namely, filler, can alleviate these problems.

wear and starting resistance of PTFE. Graphite-added

This report described the types, features, and applications

PTFE has excellent thermal conductivity and chemicalof typical fillers.

resistance. It is less abrasive to the counterpart material,
so it is economically efficient, although its abrasion
resistance is not excellent.

2. Features◦ Carbon fiber２-1）Modifiable Features

Carbon fiber-added PTFE has excellent compressiveThe addition of filler can modify features including
abrasion

resistance,creepresistance,

thermalconductivity, and coefficient of linear expansion. Modified

Table1
Filler type
Glass ﬁber

PTFE has approximately 1000 times stronger abrasion
resistance, twice the creep resistance, and up to twice
the thermal conductivity of pure PTFE. The optimal
filler should be selected depending on the desired
modification.

Glass ﬁber +graphite
Glass ﬁber +MoS2GraphiteBronze２-2）Types of Filler

Bronze + carbon ﬁber
Carbon graphite

Typical fillers include inorganic fillers such as glassCarbon ﬁber

fiber, graphite, molybdenum disulfide, and bronze.

Organic ﬁller

Organic fillers are also used.

Types and features of fillers ３）
Identifying symbol Characteristics
Excellent abrasion resistanceExcellent electrical characteristics
Attached by alkali
Poor abrasion resistance in water
Excellent creep resistance
Improves sliding properties
Excellent creep resistance and compression strength
Improves sliding properties
Excellent electrical insulation
Excellent sliding properties
Does not attach to soft opposite materials
Excellent creep resistance and compression strength
Excellent heat conductivity
Excellent sliding properties in oil
Excellent creep resistance and load
bearing properties at high temperatures
Excellent sliding property in water
Excellent creep resistance
Does not attach to soft opposite materials
Stable sliding properties
Excellent creep resistance and compression strength26

Spring 2017

Among plastic-based materials, PTFE offers diverse

No.32

Types and Application of Filler-added PTFE Materials

Table2Item
Filler contentUnit

ASTM
measuring method Pure PTFE

Amount %List of filler-added PTFE properties ３）
Filler identifying symbol

Glass ﬁber Glass ﬁber

Glass ﬁber

Compression strength Bending strength Compression creep

Speciﬁc gravity
TensionStretchGlass ﬁber
Graphite

Glass ﬁber

GraphiteBronzeCarbon/Carbon/Carbon ﬁber
graphite 25% graphite 33%

Permanentdeformation(after 24 hours)

0.2%
oﬀset

Modulus of elasticity

0.2%
oﬀset
Modulus ofelasticity
Hardness
Durometer
Impact strength (izod)
Heat conductivity
Linear expansion coeﬃcient

Water absorption rate
Limit PV value

Coeﬃcient of abrasion(in air, after 50 hours)(in water, after 50 hours)

Measuring withMatsubara-type
test instrument

Coeﬃcient of dynamic friction(after 50 hours)
Coeﬃcient of static friction

Spring 2017
No.32

strength, creep characteristics, and abrasion resistance.

◦ Organic fillers

These features are significantly improved in the high-◦ Polymide-based resin

temperature region above 200°
C. It also has excellent

Polymide based resin-added PTFE is beneficial in thesliding characteristics and good chemical resistance incase where soft metal moving parts that are likely towater. It offers excellent sliding characteristics in

be damaged by carbon-added or graphite-added PTFE

fluids of low lubricity including acid and alkaline fluids.

are used as a counterpart material.

◦ Molybdenum disulfide◦ Polyphenylene sulfide-based resin

Molybdenum disulfide-added PTFE has improved

Polyphenylene sulfide-added PTFE has creep resistancecreep resistance and lubrication. It does not degradeand dimensional stability.

electrical insulation, so it can be used for electrical◦ Aromatic polyester-based resin

usages. However, molybdenum disulfide is rarely

Aromatic polyester based resin-added PTFE has improved

added to PTFE as a single filler; it is added along withmechanical characteristics including compression andglass fiber and bronze.

bending, as well as stable sliding.

◦ Bronze
Bronze-added PTFE has significantly improved abrasion

Like these examples, there are many types of filler. Anresistance, compressive strength, creep resistance,

appropriate filler should be selected depending on thehardness, and dimensional stability. It tends to retain

usage conditions including load, sliding speed, lifespan,

oil on sliding surfaces, and has excellent abrasion

frictional

resistance under oil lubrication, so it can be used for oil

expansion,lubrication usages. However, it is important to note

properties.

that bronze-added PTFE is not suitable for electrical

Although pure PTFE is white, some fillers turn PTFE

and chemical applications.

black or dark brown. These conditions should be27

conditions,counterpart

corrosion

resistance,material,
andlinearelectricalTechnical Papers

considered depending on the position of use and theThe type of filler determines the improvement inapplication.

characteristics of PTFE. We hope the above explanationof various fillers will help our readers when selecting a

3. Conclusion
PTFE has excellent chemical characteristics, sliding
properties and non-stick, making it suitable for shaft
bearings and sliding parts. In the case where filler isadded to PTFE, the PTFE gains improved frictional andmaterial.

4. Reference１）Takaharu Ikeda. VALQUA Review; Vol.35, No.1
(1991)

creep characteristics, making it suitable for mechanical２）Takaomi Satokawa. Fluororesin Handbook

purposes.

３）VALQUA Handbook

Youichiro Wada

Spring 2017Corporate Research and Development GroupDevelopment DivisionHigh Performance Plastics Development Division

No.32

28