Toray Torelina PPS film

Torelina® is the world's first PPS film that was commercialized by Toray Torelina® excels in electrical properties and dimensional stability. Its UL-certified high temperature durability exceeds that of Lumirror®. Therefore, this material is extensively used in various applications such as mold releaser and for electronic components.

Polyphenylene Sulfide (PPS)

As shown below, PPS is a polymer simply composed of a series of alternating aromatic rings and sulfur atoms. This material was first discovered in the late 19th century, as is evidenced in studies by Friedel and Crafts.

 

However, the history of PPS as an industrial material is relatively short. In the 1940's and 1950's, many engineers failed in their attempts to produce PPS for industrial use. In 1967, however, Edmonds and Hill of Phillips Petroleum Company devised a method for producing PPS through the synthesis of para-dichlorobenzene and sodium sulfide. This marked the beginning of industrial-scale commercialization of PPS.

In 1972, Phillips Petroleum used its original manufacturing technology to begin commercial-scale production of PPS. They called the product Ryton® and it was soon noted for having effectively balanced thermal and chemical resistances, nonflammability and electrical properties. Ryton® is highly renowned today in the field of injection molding as a rapidly growing heat-resistant polymer.

1. Resistant to high and low temperatures

Long-Term Thermal Resistance

Fig. 1 is an Arrhenius plot showing the relationship between the temperature and the time taken to reduce Torelina®'s tensile strength, elongation at break and dielectric strength by half of their initial values, when forced aging is applied at various temperatures. Fig. P1 estimates Torelina®'s durability when it is used over extended periods of time at high temperature. Torelina®, having a thickness of 25µ or thicker, has received approval for long-term thermal resistance indices of 160C for mechanical properties including tensile strength and elongation at break, and 180C for dielectric strength. This approval is based on the U.S. UL-746B Standard and Japanese Electrical Appliances Regulations. Regarding dielectric strength, Torelina® is to receive approval for a long-term thermal resistance index of almost 200°C.

Fig.1 Half-Reduction Time for Various Properties vs. Temperature

 

Short-Term Thermal Resistance

For short periods of time, such as several seconds to hours, Torelina® can withstand even higher temperatures than the aforementioned long-term thermal resistance. Table P1 shows the variation of mechanical properties after Torelina® has been heated for one hour at 230C and 260C. Virtually no deterioration is found in mechanical properties of Torelina® under these testing conditions.


Table 1 Short-Term Thermal Resistance at High Temperatures

Film Thickness

µ

Property

Heating conditions

No heat treatment

230°C×1hr.

260°C×1hr.

12

Tensile Strength (MPa)

250

220

200

Elongation at Break (%)

67

71

87

Dielectric Strength (kV/mm,AC)

213

213

228

25

Tensile Strength (MPa)

250

220

170

Elongation at Break (%)

73

68

72

Dielectric Strength (kV/mm,AC)

247

239

264

75

Tensile Strength (MPa)

250

220

210

Elongation at Break (%)

72

63

79

Dielectric Strength (kV/mm,AC)

165

166

163

Test Method:

1.     Tensile Strength and Elongation: measured lengthwise according to the ASTM D882, 64T method.

2.     Dielectric Strength: measured according to the JIS C 2151 method

3. Electrical Properties

(1) Dielectric Properties

The dielectric constant of Torelina® is 3.0, and it is exceptionally stable for a wide range of temperature and frequency variations.

Dielectric Constant vs. Temperature

 

Dissipation factor vs. Temperature

 

Dielectric constant vs. Frequency

 

Dissipation factor vs. Frequency

4. Chemical Resistance ®

Torelina® features exceptionally outstanding resistance to chemicals. Table 1 indicates the variation of tensile strength in Torelina® and polyester film when they are immersed in different chemicals. Torelina®'s tensile strength remains stable in virtually all chemicals excluding concentrated sulfuric acid and nitric acid. Torelina® does not have very weak points of chemical resistance as found in polyimide and polyester films against strong base and aramid paper against acid.

Table 1 Tensile Strength of Different Films When Immersed in Chemicals (Testing conditions: 30°C, 10 days)

Chemicals

Concen-

tration

(%)

Torelina® 25µ

Polyester film 25µ

Percent tensile strength retained (%)

Remarks®

Percent tensile strength retained (%)

Remarks®

Acid, sulfuric

conc.

11

P

0

P

Acid, sulfuric

30

96

E

92

E

Acid, hydrochloric

conc.

100

E

85

G

Acid, nitric

conc.

0

P

0

P

Acid, nitric

10

97

E

92

E

Acid, glacial acetic

-

100

E

90

G

Sodium hydroxide

10

94

E

47

P

Ammonium hydroxide

conc.

100

E

0

P

Sodium carbonate

2

98

E

-

-

Iron(II) chloride

45

94

E

-

-

Hydrogen peroxide

30

80

G

-

-

Methanol

-

98

E

-

-

Ethanol

-

100

E

-

-

Acetone

-

99

E

94

E

Carbon tetrachloride

-

94

E

91

E

Benzene

-

100

E

90

G

Toluene

-

98

E

-

-

Methyl-ethyl-ketone

-

90

G

-

-

n-hexane

-

98

E

-

-

Methylene chloride

-

96

E

-

-

® E:  Excellent,    G:  Good,     P:  Poor

Gasohol Resistance

In addition to gasoline and other fuel oils, Torelina® also features a superb durability against gasohol, the gasoline-alcohol mixture which is now receiving attention as a substitute for gasoline.(See Table 2.)

 

Table 2 Gasohol Resistance of Torelina®

Gasohol

Torelina®

100  

Polyester film Lumirror® S10

100

Tensile Strength

Retained (%)

Elongation at Break

Retained (%)

Tensile Strength

Retained (%)

Elongation at Break

Retained (%)

FUEL-C Isooctane (50%) / Toluene (50%)

87

80

95

90

FUEL-C (85%) / Methanol (15%)

80

78

85

78

FUEL-C (80%) / Ethanol (20%)

82

75

92

85

FUEL-C / Lauryl peroxide (2.5%)

81

70

91

85

FUEL-C / Triethanolamine (0.5%) / Dioctylphthalate (0.2%)

81

75

65

35

 

Testing conditions: 60C, 500 hours

Freon Resistance

As shown in Table 3, Torelina® has a high resistance to Freon, the substance used as a refrigerant in air conditioners, etc., and the amount of extract is very small.

<Table 3 Freon Resistance of Torelina®>

1. Testing conditions

(1) Torelina®: 250, (2)Freon: R134a, (3) Temperature: 170C (vapor phase)

(4) Pressure:      3.43.5MPa

Film

Properties

After 500 hr.

Torelina®

(250)

Strength Retained (%)

100

Elongation Retained (%)

80

PET film

(250)

Strength Retained (%)

60

Elongation Retained (%)

5

PEN film(250)

Strength Retained (%)

48

Elongation Retained (%)

2

 

5. Hydrolysis Resistance

Hydrolysis Resistance

PPS is a polymer which shows virtually no hydrolysis. Accordingly, Torelina® features outstanding resistance to hydrolysis. Fig. 1 shows the decrease of elongation at break of various thin films when placed in saturated water vapor at 155C. In absolutely dry conditions polyimide film boasts better thermal resistance than Torelina®. In water vapor, however, it deteriorates much more rapidly.

Fig. 1 Hydrolysis Resistance of Various Films(Decrease of elongation at break in saturated water vapor at 155C)

6. Creep Characteristics

Figure below compares the creep characteristics of Torelina® with polyester films.

In comparison with other films, Torelina® exhibits a lower dimensional change even after being subject to stress for long periods of time.

 

Creep Characteristics of Torelina®

 

7. Applications

Capacitors (SMT, high-temperature, high-frequency, high - reliability)

Variable capacitors

Flexible printed circuit boards, keyboard membranes

Motor/transformer insulation, flat motors

Cable wrapping

Industrial tapes, interior coverage materials

Acoustic membranes, diaphragms

Microwave oven-ready food packing, etc.