Transcript Compounding technique

Compounding Technique
Rubber compounding
What is rubber compounding?
Why we are doing?
How can we do it successfully?
Definition of Rubber Compounding
• is the art and science of selecting and
combining elastomers and additives to
obtain an intimate mixing that will develop
the necessary physical and chemical
properties for a finished product.
Objective of Rubber Compounding
1. To secure certain properties in the finished
product to satisfy service requirements.
2. To attain processing characteristics necessary
for efficient utilization of available equipment.
3. To achieve the desirable properties and
processability at lowest possible cost.
To be Sucessful in Compounding
• Must understand the properties and
function of hundreds of elastomers and
rubber chemicals
• Must also have intimate knowledge of the
equipment used for mixing, extrusion,
calendering, molding and vulcanization.
Procedure for Compound
Development
• 1. Set specific objectives (properties, price,
etc.).
• 2. Select base elastomer(s).
• 3. Study test data of existing compounds.
• 4. Survey compound formulations and
properties data presented by material
suppliers in their literature .
• 5. Choose a starting formulation.
To be continued
• 6. Develop compounds in laboratory to
meet objectives.
• 7. Estimate cost of compound selected for
further evaluation.
• 8. Evaluate processability of compound in
factory.
• 9. Use compound to make a product sample
• 10. Test product sample against
performance specification.
Classification of Compounding
Ingredients
1. Elastomers
2. Vulcanizing Agents (Curatives)
3. Accelerators
4. Activators and Retarders
5. Antidegradants(Antioxidants, Antiozonants,
Protective Waxes)
• 6. Processing Aids(Peptizers, Lubricants,
Release Agents)
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To be continued
• 7. Fillers (Carbon Blacks, Non-black
Materials)
• 8. Plasticizers, Softeners, and Tackifiers
• 9. Color Pigments
• 10. Special Purpose Materials(Blowing
Agents, Reodorants, etc,)
Requirements of Rubber
Compound for Good Processing
• 1. Uniform plasticity and recovery.
• 2. Uniform scorch rate.
• 3. Uniform rate of cure.
Vulcanizing Agents
• To cause chemical reaction resulting in
crosslinking of elastomer molecules.
• Sulfur is by far the most widely used.
VULCANIZING AGENTS
• TYPE
• Sulfur or Sulfurbearing Materials
COMMON USE
Natural Rubber,
Isoprene, SBR, Buty1,
Butadiene, EPDM,
Nitrile,Norsorex
• Organic Peroxides Urethane, Silicone,
Chlorinated Polyethylene,
Crosslinked Polyethylene,
Vamac, Vynathene, PVC/
Nitrile
To be continued
• TYPE
• Metallic Oxides
• Organic Amines
• Phenolic Resins
COMMON USE
Neoprene,
Hypalon,Thiokol
Acrylic,
Fluorocarbon,
Epichlorohydrin,
Vamac
Butyl
ACCELERATORS
• Use to reduce vulcanization time, or cure
time by increasing the speed of
vulcanization
• Most are organic substance containing both
nitrogen and sulfur(Today)
• Inorganic accelerator was widelyused years
ago (litharge, lime, and magnesia)
ORGANIC ACCELERATORS
• TYPE
EXAMPLE
TYPICAL USE
• Aldehyde-amine
Reaction product of
butyral dehyde and
aniline
Fast curing
accelerator for
reclaim,hard
rubber and selfcuring cements
• Amines
Hexamethylene
tetramine
Delayed action
slow accelerator
for natural rubber
To be continued
• TYPE
• Guanidines
EXAMPLE
Diphenyl guanidine
(DPG)
TYPICAL USE
Secondary accelerator
to activate thiazole
type accelerator
• Thioureas
Ethylene thiourea
Fast curing accelerator
(ETU)
for Neoprene,Hypalon
and Epichlorohydrin
To be continued
• TYPE
• Thiazoles
EXAMPLE
Benzothiazyldisulfide
(MBTS)
• Thiurams
Tetramethylthiuram
disulfide (TMTD)
TYPICAL USE
Safe-processing
moderately fast
curing accelerator
for natural rubber,
Isoprene,SBR,
Nitrile,Butyl and
EPDM
Fast curing sulfurbearing accelerator
for SBR, Nitrile,
Butyl and EPDM
To be continued
• TYPE
EXAMPLE
• Sulfenamides N-cyclohexyl-2benzothiazylsulfenamide
(CBS)
TYPICAL USE
Safe-processing,
delayed action
accelerator for
natural rubber,
SBR and Nitrile
• Dithiocarbamates Zinc dimethyl Fast curing
accelerator
• Xanthates
Dibutylxanthogen Fast curing, low
disulfide
temperature
accelerator for
natural rubber and SBR
Activators and Retarders
• Activators
- used to activate the accelerator and
improve its effectiveness (ZnO, stearic acid,
litharge, magnesia, and amine)
- attain good crosslink efficiency
• Retarders
- used to reduce the scorchness (phthalic
anhydride, salicylic acid and sodium
acetate)
Antidegradants
• To retard the deterioration of rubber
compounds initiated by
- oxygen, ozone
- heat, light
- metal catalyst and
- mechanical flexing
PROCESSING AIDS
• To facilitate processing operation such as
- Mixing
- Calendering
- Extrusion and
- Molding
PROCESSING AIDS
• COMPOSITION
•
EXAMPLE(Tradenames)
Activated Dithio-
Pepton 44
FUNCTION
Peptizer for NR
bisbenzanilide
• Polyparadinitrosobenzene
Polyac
Chemical conditioner
for IIR
To be continued
• COMPOSITION
EXAMPLE(Tradenames)
• Xylyl mercaptans RPA3
FUNCTION
Peptizer for NR, IR,
SBR and NBR.
Stabilizer for cement
viscosity
• Low-molecularweight
polyethylene
A-C Polyethylene
617 A
Release agent,
lubricant
• Calcium oxide
DesiCal P
Dessiccant
To be continued
• COMPOSITION
• Aliphaticnaphthenicaromatic resins
• Paraffin Wax
• Polyethylene
glycol
• Petroleum
hydrocarbon
EXAMPLE(Tradenames)
Strucktol 60NS
FUNCTION
Homogenizing
agent for all
elastomers
Numerous
Release agent,
lubricant
Carbowax PEG3350 Activator for
silica lubricant
Petrolatum
Release agent,
lubricant
Fillers
• To reinforce physical properties
• To reduce cost
• Devided into two types(Reinforcing and
Extending)
• Selection of reinforcing filler is the third
most important task in compounding(next to
elastomer and cure system)
Types of Fillers
• Reinforcing Type
Carbon Black (listed in order
of increasing particle size)
Non-Black
N220 (ISAF)
N330 (HAF)
N550 (FEF)
N762 (SRF-LM)
N990 (MT)
- Silica
- Zinc Oxide
- Magnesium Carbonate
- Aluminum Silicate
- Sodium Aluminosilicate
- Magnesium Silicate
Types of Fillers (continued)
Extending Type
- Calcium Carbonate
- Barium Sulfate
- Aluminum Trihydrate
- Talc
Hardness
NR has hardness itself (no filler) 35-40 IRHD
• ISAF
1.7 phr increases 1
IRHD
• HAF
1.9 phr increases 1
IRHD
• Hisil 233
2 phr increases 1
IRHD
• Hard clay
5 phr increases 1
IRHD
• Soft clay
7.7 phr increases 1
IRHD
• Whiting
CaCO3
6.4 phr increases 1
IRHD
2 phr decreases 1
IRHD
• Oil
Particles Size
• Play a major role in the tensile strength
small particle size
highest tensile
strength
at optimum
loading
• Fine fillers is difficult to process (need more
energy for their dispersion into the elastomer)
• Effects Mooney scorch
small particle size
the scorch resistance
PLASTICIZERS,SOFTENERS,
AND TACKIFIERS
• Objective for Using
- Aid mixing,
- Modify viscosity,
- Produce tack,
- Provide flexibility at low temperature
Selection of Plasticizers
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The important criteria are:
Compatibility
Efficiency
Cost
Example:
- Aromatic type oil is not compatibe with
NR, Isoprene, IIR, EPDM
- Paraffinic type oil is not compatible with
SBR, butadiene, NBR, CR
PLASTICIZERS,SOFTENERS,
AND TACKIFIERS
• CATEGORY OF MATERIAL
• Petroleum Oils -Aromatic
- Paraffinic
- Naphthenic
FUNCTION
Plasticizer,Softener
• Ester Plasticizers - Dioctyl phthalate
- Dioctyl sebacate
- Tributoxyethyl phospate Low temperature
- Di (butoxyethoxyethyl) formal
plasticizers
- Triglycol ester of vegetable oil
To be continued
• CATEGORY OF MATERIAL
FUNCTION
• Vulcanized Vegetable Oils
Extender, Plasticizer
• Asphaltic Hydrocarbon
Extender, Plasticizer
• Pine Tar
Plasticizer,Tackifier
• Resins -Coumarone-indene
- Petroleum
- Phenolic
Tackifier,Plasticizer
• Polymeric esters
Extender, Plasticizer
• Rosins - Hydrogenated rosin
Tackifier
Special Purpose Materials
• Not require in the majority of rubber
compound
• Used for specific purpose
Example:
- Blowing agents
- Reodorants
- Adhesion promotors
- Flame retardant
- Fungicide
- UV light absorbers