compounding technique. rubber compounding what is rubber compounding? why we are doing? how can we...
TRANSCRIPT
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 comb
ining elastomers and additives to obtain an i
ntimate mixing that will develop the necess
ary physical and chemical properties for a fi
nished product.
Objective of Rubber Compounding
1. To secure certain properties in the finished prod
uct to satisfy service requirements.
2. To attain processing characteristics necessary f
or efficient utilization of available equipment.
3. To achieve the desirable properties and process
ability at lowest possible cost.
To be Sucessful in Compounding
• Must understand the properties and function
of hundreds of elastomers and rubber chemic
als
• Must also have intimate knowledge of the eq
uipment used for mixing, extrusion, calender
ing, 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)
To be continued
• 7. Fillers (Carbon Blacks, Non-black Mater
ials)
• 8. Plasticizers, Softeners, and Tackifiers
• 9. Color Pigments
• 10. Special Purpose Materials(Blowing Age
nts, 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 cros
slinking of elastomer molecules.
• Sulfur is by far the most widely used.
VULCANIZING AGENTS
• TYPE COMMON USE
• Sulfur or Sulfur- Natural Rubber, bearing Materials Isoprene, SBR, Buty1,
Butadiene, EPDM, Nitrile,Norsorex
• Organic Peroxides Urethane, Silicone,
Chlorinated Polyethylene, Crosslinked Polyethylene, Vamac, Vynathene, PVC/Nitrile
To be continued
• TYPE COMMON USE• Metallic Oxides Neoprene,
Hypalon,Thiokol• Organic Amines Acrylic,
Fluorocarbon, Epichlorohydrin, Vamac
• Phenolic Resins 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 Fast curing
butyral dehyde and accelerator for
aniline reclaim,hard
rubber and self-
curing cements
• Amines Hexamethylene Delayed action
tetramine
slow accelerator
for natural rubber
To be continued
• TYPE EXAMPLE TYPICAL USE
• Guanidines Diphenyl guanidine Secondary accelerator
(DPG) to activate thiazole
type accelerator
• Thioureas Ethylene thiourea Fast curing accelerator
(ETU) for Neoprene,Hypalon
and Epichlorohydrin
To be continued
• TYPE EXAMPLE TYPICAL USE• Thiazoles Benzothiazyldisulfide Safe-processing
(MBTS) moderately fast curing accelerator for natural rubber,
Isoprene,SBR,
Nitrile,Butyl and EPDM
• Thiurams Tetramethylthiuram Fast curing sulfur- disulfide (TMTD) bearing accelerator
for SBR, Nitrile, Butyl and EPDM
To be continued
• TYPE EXAMPLE TYPICAL USE• - - - - 2Sulfenamides N cyclohexyl Safe processing,
bbbbbbbbbbbb- bbbbbbb bbbbbb bbbbbbbbbbb
bbbbbbbbbbb bbb () natural rubber, SBR and Nitrile
• bbbbbbbbbbbbbbbb bbbb bbbbbbbb bbbb bbbbbb bbbbbbbbbbb
• bbbbbbbbb Dibutylxanthogen Fast curing, low bbbbbbbbb bbbbbbbbbbb
bbbbbbbbbbb bbb 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 compo
unds 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) FUNCTION
• - 44ActivatedDithio Pept on Pept i zer f or NR
bbbbbbbbbbbbbb
• - Poly Polyac Chemical conditioner
paradinitrosobenzene for IIR
To be continued
• COMPOSITION EXAMPLE(Tradenames) FUNCTION
• Xylyl mercaptans RPA3 Peptizer for NR, IR,
SBR and NBR.
Stabilizer for cement
viscosity
• Low-molecular- A-C Polyethylene Release agent, wei
ght 617 A lubricant polyethylen
e
• Calcium oxide DesiCal P Dessiccant
To be continued
• COMPOSITION EXAMPLE(Tradenames) FUNCTION
• Aliphatic- Strucktol 60NS Homogenizing naphthenic-
agent for all aromatic resins elastomers
• Paraffin Wax Numerous Release agent, lubricant
• Polyethylene Carbowax PEG3350 Activator for glycol silica lubricant
• Petroleum Petrolatum Release agent, hydrocarbon 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 N220 (ISAF) of increasing particle size) N330 (HAF) N550 (FEF) N762 (SRF-LM) N990 (MT)
Non-Black - Silica - Zinc Oxide
- Magnesium Carbonate - Aluminum Silicate - Sodium Aluminosilicate - Magnesium Silicate
Types of Fillers (continued)
Extending Type
- Calcium Carbonate
- Barium Sulfate
- Aluminum Trihydrate
- Talc
HardnessNR 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 6.4 phr increases 1IRHD CaCO3
• Oil 2 phr decreases 1 IRHD
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
reduces
PLASTICIZERS,SOFTENERS, AND TACKIFIERS
• Objective for Using -
Aid mixing, -
Modify viscosity, -
Produce tack, -
Provide flexibility at low temperature
Selection of Plasticizers• 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 FUNCTION
• Petroleum Oils -Aromatic Plasticizer,Softener
- Paraffinic
- Naphthenic
• 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 Tackifier,Plasticizer
- Petroleum
- Phenolic
• Polymeric esters Extender, Plasticizer
• Rosins - Hydrogenated rosin Tackifier
Special Purpose Materials• Not require in the majority of rubber compo
und
• Used for specific purpose Example:
- Blowing agents - Reodorants
- Adhesion promotors - Flame retardant - Fungicide - UV light absorbers