Introduction to Process Oils

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Krisda SUCHIVA

Research and Development Centre for Thai Rubber Industry,Mahidol University

INTRODUCTION TO PROCESS OILS


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Process oils are used in the rubber industry to,

improve the processability of rubbers and rubbercompounds

process aids

increase the bulk of rubber in order to lower cost

oil-extended rubbers

Main application is process aid.

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Process aids are increasingly important for the rubberindustry due to the following needs,

- improve efficiency and productivity

- lower energy consumption

In total,

- reduce production cost

- improve product quality

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1. reduce viscosity

2. reduce elasticity

3. aid dispersion of fillers

4. reduce power consumption

Additional requirement

1. do not affect intended properties of finished products

2. act at low dosage level

3. non-toxic

Functions of process aids,

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1. chemical peptizers

2. fatty acid soaps

3. fatty acid ester

4. petroleum oils

5. factice

6. resins

7. partially vulcanised rubber

8. liquid polymers

9. waxes

Materials used as process aids,

Process oil is just one of the process aids. 5


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For reduction of viscosity and elasticity

2 Mechanisms,

1. Lowering molecular weight of polymer

How do process aids work ?

molecular entanglement reduced

easier flow of molecules

peptizer

Chemical processing aids 6


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2. Lowering of intermolecular interactions

process aid

flow of molecules become easier

e.g. fatty acid soaps, fatty acid ester, oils, liquid polymers.

Most process aids work on this principle

No reduction in MW, hence the final properties not affected

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Efficiency of physical process aids depend on degree of miscibilitywith polymer or solubility in polymers.

completely miscible

or

completely soluble

most efficient

most effective in reducingviscosity

only small amount is required.

partially miscible

or

partially soluble

less efficient

less effective in reducingviscosity

Higher amount is required.

immiscible

or

insoluble

least efficient

least effective in reducing

viscosity

large amount is required. 8


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PROCESS OILS

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derivatives naphthalene, debenzothiophene,carbazole, etc.

PROCESS OILS

PROCESS OILS are derived from petroleum (crude oil) after themore volatile petrol and heating oil fractions have been removed bydistillation.

PROCESS OILS are MIXTURES of paraffinic, naphthenic andaromatic compounds of wide distribution of molecular weight.

Origin and Composition of Process Oils

Paraffinic oils

Naphthenic oils

Aromatic oils

CH3CH2CH2CH2CH2 CH3CHCH2CHCH2CH3CH2

CH3 CH3paraffins isoparaffins

derivatives of cyclohexane or decalin

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PROCESS OILS

Type of Process Oils

Type%

paraffinic

%

naphthenic

%

aromaticVGC

Paraffinic oil 60-74 20-35 0-10 0.790-0.819

Naphthenic oil 35-45 30-45 10-30 0.850-0.899

Aromatic oi l 20-35 20-40 35-50 0.950-0.999

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PROCESS OILS

1. solubility or miscibility or compatibility with rubbers

Determine efficiency in reducing viscosity/flow characteristics

Depends on,

- % Aromaticity : the higher, the more efficient

- molecular weights (viscosity) : the smaller, the moreefficient

High solubility means more oil can be incorporated into the

rubber higher loading of oil possible.

Important Properties of Process Oils

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PROCESS OILS

Level of aromaticity measured by

1) VISCOSITY GRAVITY CONSTANT (VGC)


High VGC = high aromaticity

2) ANILINE POINT Aniline point = temperature at which equal volumes

oil and aniline are mutually soluble.

Low Aniline Point = high aromaticity

note : ● Aniline point can be influenced by MW of oil.● Can be difficult to determine with very dark and opaque oils.

specific gravity

= 1.0752-a10

G

VGC

log(V+38)a

Viscosity (saybolt)

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PROCESS OILS


Compatibility of process oils with various rubbers

Oil Type RubbersNR SBR BR NBR CR EPDM IIR

Paraffinic + + + - - + +

Naphthenic + + + 0 0 + 0

Aromatic + + + + + 0 -

+0-

compatiblepartially compatibleincompatible

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PROCESS OILS

2. Colour stability/Contact staining

Colour stability (increasing darkness) decreases with

increasing % aromaticity.


paraffinic oils > naphthenic oils > aromatic oils

3. Ageing resistance

Ageing resistance decrease with increasing % aromaticity.

paraffinic oils > naphthenic oils > aromatic oils

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PROCESS OILS

4. Loss of oil during high temperature service of rubberproduct containing oil.

Determined by FLASH POINT

5. Toxicity

Become increasingly important

Process oils contain Polycyclic Aromatic Hydrocarbons (PAHs)

or Polycyclic Aromatic (PCA) which are carcinogen and cancause mutation.

Regulations (European Directive 2005/69/EC) imposed ban ofprocess oils containing ≥ 10mg/kg (ppm) of PAH since2010.


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PROCESS OILS

Trend towards low PAH (


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PROCESS OILS

Polycyclic Aromatic Hydrocarbons

PAHS Chemical Formulas MW (g.mol-1) Chemical Structures

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PROCESS OILS

Polycyclic Aromatic Hydrocarbons

PAHS Chemical Formulas MW (g.mol-1) Chemical Structures

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PROCESS OILS

Comparison of Different Process Oils

Effects on properties of rubber compounds and vulcanisates

Process Oils Compared

Sample number Saybolt viscosity VGC

38°C 100°C

Aromatic123

43603500

-

2109681

0.9910.9540.981

Naphthenic

456

78910

25202206760

156-

110104

85.984.760

41.043.538.238.0

0.8830.8820.869

0.8780.8300.8860.871

Paraffinic

11121314

15

2642500-

110

-

15563.542.340.4

38.0

0.8000.8030.8050.807

0.832 20


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PROCESS OILS

Part by weight

NR

Zinc oxideStearic acidN-330 carbon blackN - Isopropyl-N ’ -phenyl-p -phenylenediamineOilN - Oxydiethylenebenzothiazole-2-sulphenamideSulphur

100

52.5

45

1.5

10 or 20

0.8

2.5

Time (min) Action

00.51.02.0

3.5

Add rubber.

Add small powders.

Add half black.

Half black plus oil.

Dump.

FORMULATION FOR OIL EVALUATION

MIX CYCLE : BR BANBURY


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PROCESS OILS

Effects on Mooney Viscosity

Naphthenic oils tend to give lower

mooney viscosity

Paraffinic oils tend to give lower

mooney viscosity

20 phr


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Aromatic Oi ls Naph thenic Oil s Paraffinic Oils

10

2020

40

30

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Mooney v iscosi ty, ML 1+4, 100 °C

Aromatic Oi ls Naphthenic Oil s Paraffinic Oils

10 phr

10

20

30

50

40

60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Mooney v iscosi ty, ML 1+4, 100 °C


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PROCESS OILS

Vulcanisation Characteristics (ODR 100°C)

Oil Type Sample 10 phr oil 20 phr oil

ts5

(min)

Tc(90)

(min)

MHR ML

(torque units)

ts5

(min)

Tc(90)

(min)

MHR ML

(torque units)

Aromatic123

4.123.424.16

14.3313.1313.47

33.035.632.9

7.357.458.25

4.513.584.25

16.0014.3214.28

24.327.230.3

8.467.089.00

Naphthenic

4567

8910

3.583.535.163.52

3.473.484.15

14.3113.4014.5114.43

14.2814.2113.56

32.535.530.233.5

32.135.532.7

7.397.369.257.41

8.167.377.58

4.394.285.004.17

4.254.174.31

15.1815.1116.0514.50

15.2416.0215.18

28.727.425.430.5

27.827.227.6

8.168.258.537.50

8.428.227.58

Paraffinic

1112131415

4.073.574.044.004.21

14.2014.2214.4513.4514.06

34.633.433.932.535.5

7.447.527.577.137.28

4.264.354.354.294.39

15.1314.3216.2814.5815.00

28.028.826.327.226.4

8.078.168.568.288.14

Little difference was observed for various oil types at 10 and 20 phr. 23



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PROCESS OILS

Effect on Hardness

Some effects on hardness

Average Values of Hardness forthe Three Oil Types

Dosage ph r )

A N P

10 62 61.5 62

20 56.5 56 54.5

• Almost no effect on hardness at10 phr.

• At 20 phr. paraffinic oils showslightly greater softening effect.


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Hardness, IRHD

Aromatic Naph thenic Paraffinic

20 phr

10

20

30

50

40

70

60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


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PROCESS OILS

Effect on Tensile Strength

• Individual oils gave widely different values of T.S• Effect of different types of oils on unaged, 70°C aged or

100°C aged are slight. 25

Tensile strength, MPa

Aromatic Naphthenic Paraffinic

20 phr of oil

5

10

15

25

20

30

1

2 34 5

6 7

8

910

11 12 13 14 15

unaged

aged 3 days 100°C

aged 28 days 70°C

aged 7 days 100°C



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PROCESS OILS

Effect on Compression Set

Paraffinic and naphthenic oils tend to give lower

compression set values than aromatic oil. 26

Compression set, %

Aromati c Naphthenic Paraffinic

20 phr of oil/25% initial compression

10

20

30

50

40

60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1 day 100°C

7 days 70°C



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PROCESS OILS

Effect on Dunlop Resilience

• Aromatic oil gave lower resilience• Higher viscosity oils gave lower resilience

Dunlop resilience, 23°C, %

Aromatic Naphthenic Paraffinic

20 phr of oil

20

30

40

60

50

80

70

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

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PROCESS OILS

Performance of Low PAH/PCA Oils

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Rolling Resistance

DAE TDAE MES NAP RAE

110

108106

104

102

100

98

96

9492

90

Wet Grip

Rolling Resistance

TDAE

MES

NAP

RAE

+-

+

-


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PROCESS OILS

SUMMARY

1. Process oils are used to improve the processability of rubber

compounds or to increase the bulk of rubber in order to lower cost.

2. Although process oils are classified as paraffinic (CP) naphthenic

(CN) or aromatic (CA), they are mixtures of CP/CN/CA.

3. The efficiency of oil in reducing viscosity and elasticity depends on

its compatibility with rubber or its solubility in rubber.

- good compatibility/solubility efficient

- smaller quantity may be used.

4. Compatibility or efficiency depends on

- % aromaticity : the higher, the more efficient

- MW or viscosity : the smaller, the more efficient29


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Q & A

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Introduction to Process Oils

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