RUBBER COMPOUNDING RUBBER COMPOUNDING TECHNOLOGYTECHNOLOGY

SUDHA.PSUDHA.P DEPUTY DIRECTOR(RIDT) DEPUTY DIRECTOR(RIDT)

RUBBER TRAINING INSTITUTERUBBER TRAINING INSTITUTE DEPARTMENT OF TRAININGDEPARTMENT OF TRAINING

RUBBER BOARDRUBBER BOARDKOTTAYAM-686 009KOTTAYAM-686 009

sudha@rubberboard.org.insudha@rubberboard.org.inMob: 94964 13731Mob: 94964 13731

RUBBER RUBBER COMPOUNDINGCOMPOUNDING

COMPOUNDCOMPOUNDIt is a homogenous mixture of ingredients used in a It is a homogenous mixture of ingredients used in a particular product manufacture such that the properties particular product manufacture such that the properties of most of the ingredients are unchanged in the final of most of the ingredients are unchanged in the final product whereby providing a defined set of product whereby providing a defined set of mechanical properties.mechanical properties.

COMPOUNDINGCOMPOUNDINGIt is the science of selecting and combining elastomers It is the science of selecting and combining elastomers and additives to obtain physical and chemical and additives to obtain physical and chemical properties for a finished product.properties for a finished product.

RUBBER COMPOUNDINGRUBBER COMPOUNDING

OBJECTIVEOBJECTIVE

1.1. To secure To secure certain properties in the finished product to certain properties in the finished product to satisfy the service requirements.satisfy the service requirements.

2.2. To attain processing characteristics necessary for efficient To attain processing characteristics necessary for efficient utilization of available equipment.utilization of available equipment.

3.3. To achieve desirable properties and processability at the To achieve desirable properties and processability at the lowest cost.lowest cost.

The most important factor in compounding is to secure an The most important factor in compounding is to secure an acceptable balance among demands arising from the above acceptable balance among demands arising from the above three criteria.three criteria.

MAJOR OBJECTIVES OF COMPOUND MAJOR OBJECTIVES OF COMPOUND DEVELOPMENTDEVELOPMENT

PROCESS REQUIREMENTPROCESS REQUIREMENT Proper mixing (Incorporation, dispersion, distribution and Proper mixing (Incorporation, dispersion, distribution and

plasticization)plasticization) Viscosity/process safety (ML1+4, MS)Viscosity/process safety (ML1+4, MS) Stickiness and tackinessStickiness and tackiness Shaping (Calendering, Extrusion, Assembling and Moulding)Shaping (Calendering, Extrusion, Assembling and Moulding)

COMPOUND PROPERTY REQUIREMENTCOMPOUND PROPERTY REQUIREMENT Hardness Hardness Stress-Strain properties (TS, EB, M-100, M-300, tear)Stress-Strain properties (TS, EB, M-100, M-300, tear) Abrasion resistanceAbrasion resistance Hysteresis & set propertiesHysteresis & set properties Resistance to cut growth, fatigue, flex crackingResistance to cut growth, fatigue, flex cracking

MAJOR OBJECTIVES OF COMPOUND MAJOR OBJECTIVES OF COMPOUND DEVELOPMENTDEVELOPMENT

RESISTANCE TO DEGRADATIONRESISTANCE TO DEGRADATION

Heat, Oxygen, OzoneHeat, Oxygen, Ozone FlameFlame LiquidsLiquids LightLight

MISCELLANEOUS PROPERTY REQUIREMENTSMISCELLANEOUS PROPERTY REQUIREMENTS Low temperature flexibilityLow temperature flexibility Electrical propertiesElectrical properties PermeabilityPermeability Contact with food stuff and drugsContact with food stuff and drugs Bonding to metal & textilesBonding to metal & textiles SwellingSwelling Other specific requirementsOther specific requirements

CLASSIFICATION OF COMPOUNDING CLASSIFICATION OF COMPOUNDING INGREDIENTSINGREDIENTS

1.1. ElastomersElastomers2.2. Vulcanizing Agents (curatives)Vulcanizing Agents (curatives)3.3. AcceleratorsAccelerators4.4. Activators and RetardersActivators and Retarders5.5. Antidegradants (Anti-oxidants, Antiozonants, Protective Antidegradants (Anti-oxidants, Antiozonants, Protective

waxes )waxes )6.6. Processing aids (Peptisers, Lubricants, Release Agents)Processing aids (Peptisers, Lubricants, Release Agents)7.7. Fillers (carbon black, non-black materials)Fillers (carbon black, non-black materials)8.8. Plasticizers, Softeners and TackifiersPlasticizers, Softeners and Tackifiers9.9. Colour pigmentsColour pigments10.10. Special Purpose Materials (Blowing Agents, Deodorants, Special Purpose Materials (Blowing Agents, Deodorants,

etc.)etc.)

COMPOUND DESIGNCOMPOUND DESIGN

DESIGN REQUIREMENTSDESIGN REQUIREMENTS SERVICE REQUIREMENTS/VULCANISATE PROPERTIESSERVICE REQUIREMENTS/VULCANISATE PROPERTIES PROCESSABILITYPROCESSABILITY ECONOMICSECONOMICS

DESIGN BASED ON DESIGN BASED ON CUSTOMER SPECIFICATION/REQUIREMENTSCUSTOMER SPECIFICATION/REQUIREMENTS COMPETITOR'S SAMPLECOMPETITOR'S SAMPLE DEVELOP A NEW PRODUCT DEVELOP A NEW PRODUCT

POLYMER SELECTION POLYMER SELECTION CRITERIACRITERIA CostCost Ease of mixingEase of mixing Strength requirementsStrength requirements Modulus or stiffness requirementModulus or stiffness requirement Abrasion resistance requirementAbrasion resistance requirement Elongation requirementElongation requirement Oil resistance requirementOil resistance requirement Low temperature requirementLow temperature requirement Fatigue requirementFatigue requirement TackTack Set of stress relaxationSet of stress relaxation Service temperatureService temperature Dynamic properties (hysteresis, damping resistance)Dynamic properties (hysteresis, damping resistance) FlammabilityFlammability Chemical resistanceChemical resistance

POLYMER SELECTION POLYMER SELECTION

SHOULD HAVE THOROUGH KNOWLEDGE ABOUT POLYMER SHOULD HAVE THOROUGH KNOWLEDGE ABOUT POLYMER PROPERTIESPROPERTIES

REFER STANDARD SELECTION CHARTS/COMPARATIVE REFER STANDARD SELECTION CHARTS/COMPARATIVE CHARTSCHARTS

BLENDS OF POLYMERSBLENDS OF POLYMERS PROCESSABILITY FACTOR-suitability for the processes and methods PROCESSABILITY FACTOR-suitability for the processes and methods

adoptedadopted COST FACTORCOST FACTOR AVAILABILITY OF DATA ON POLYMER GRADES, PROPERTIES, AVAILABILITY OF DATA ON POLYMER GRADES, PROPERTIES,

START UP FORMULATIONS ETC.START UP FORMULATIONS ETC.

VULCANIZING AGENTSVULCANIZING AGENTS

TYPETYPE COMMON USECOMMON USE

Sulphur or Sulphur bearing Sulphur or Sulphur bearing materialsmaterials

Natural Rubber, Isoprene, SBR, Natural Rubber, Isoprene, SBR, Butyl, Poly Butadiene, EPDM, Butyl, Poly Butadiene, EPDM, NitrileNitrile

Organic PeroxidesOrganic Peroxides Urethane, Silicone, Chlorinated Urethane, Silicone, Chlorinated Polyethylene, PVC/NitrilePolyethylene, PVC/Nitrile

Metallic OxideMetallic Oxide Polychloroprene, Chlorosulphonated Polychloroprene, Chlorosulphonated Polyethylene, PolysulphidePolyethylene, Polysulphide

Organic AminesOrganic Amines Acrylic, Fluorocarbon, Acrylic, Fluorocarbon, EpichlorohydrinEpichlorohydrin

Phenolic ResinsPhenolic Resins ButylButyl

CURING SYSTEMCURING SYSTEM

Selection of curing system is based on:Selection of curing system is based on: Base polymerBase polymer Processing conditionsProcessing conditions Curing conditionsCuring conditions Service requirementService requirement

Base polymerBase polymer Saturated rubber – peroxide e.g. EPR with DCPSaturated rubber – peroxide e.g. EPR with DCP Unsaturated rubber-peroxide, sulphur/accelerator & resins, e.g. EPDM Unsaturated rubber-peroxide, sulphur/accelerator & resins, e.g. EPDM

with DCP, NR with sulphur accelerator, IIR with Resinwith DCP, NR with sulphur accelerator, IIR with Resin Special Polymers – Metal oxide, Dioxime, Resin e.g. CR with ZnO/MgOSpecial Polymers – Metal oxide, Dioxime, Resin e.g. CR with ZnO/MgO

ACCELERATORSACCELERATORS

An accelerator is usually a complex organic chemical which takes part in the An accelerator is usually a complex organic chemical which takes part in the vulcanization, thereby reducing the vulcanization time considerably- Organic vulcanization, thereby reducing the vulcanization time considerably- Organic amines & its derivatives . It also improves the properties. Its action may be:amines & its derivatives . It also improves the properties. Its action may be:

slow- eg. Guanidinesslow- eg. Guanidines, , Diphenyl guanidine (DPG)Diphenyl guanidine (DPG) Di ortho tolyl guanidine(DOTGDi ortho tolyl guanidine(DOTG) )

mediummedium- eg. Thiazoles, - eg. Thiazoles, Mercapto benzo thiazole (MBT)Mercapto benzo thiazole (MBT) Di benzthiazyl di sulphide) (MBTS) Di benzthiazyl di sulphide) (MBTS)

fast ( ultra)-fast ( ultra)- eg. Thiurams, eg. Thiurams, Tetramethyl thiuram monosulphide (TMTM)Tetramethyl thiuram monosulphide (TMTM) Tetramethyl thiuram di sulphide (TMT)Tetramethyl thiuram di sulphide (TMT)

Dithiocarbamates, Dithiocarbamates, Zinc diethyl dithiocarbamate (ZDC)Zinc diethyl dithiocarbamate (ZDC) Zinc dibutyl dithiocarbomate(ZDBC)Zinc dibutyl dithiocarbomate(ZDBC)

Delayed-action fast- eg. SulfenamidesDelayed-action fast- eg. SulfenamidesCyclohexyl benzthiazyl sulfenamide (CBS)Cyclohexyl benzthiazyl sulfenamide (CBS)Dicyclohexyl benzthiazyl sulfenamide (DCBS)Dicyclohexyl benzthiazyl sulfenamide (DCBS)Morpholino thio benzthiazylsulfenamide (MOR)Morpholino thio benzthiazylsulfenamide (MOR)Tertiary butyl benzthiazyl sulfenamide (TBBS)Tertiary butyl benzthiazyl sulfenamide (TBBS)

CURING SYSTEM (Contd..)CURING SYSTEM (Contd..)

Accelerator ActivatorAccelerator Activator ZnO and Stearic acid for sulphur cure systemZnO and Stearic acid for sulphur cure system TAC for peroxide cure systemTAC for peroxide cure system

Processing conditionProcessing condition Type of processing equipment usedType of processing equipment used Temperature build up during processingTemperature build up during processing Extent of rework usageExtent of rework usage Rheological property requirementRheological property requirement

Curing conditionsCuring conditions Type of the productType of the product Method of curing employedMethod of curing employed Temperature of curingTemperature of curing Flow requirement during curingFlow requirement during curing

CURING SYSTEM (Contd..)CURING SYSTEM (Contd..)

Service RequirementsService Requirements Service temperatureService temperature Duration of exposure Duration of exposure Mechanical property requirement.Mechanical property requirement. Dynamic property requirementDynamic property requirement Ageing behaviour and permanent set requirements.Ageing behaviour and permanent set requirements. Special property requirement.Special property requirement.

FILLERSFILLERS

• Fillers are materials used to extent the range of Fillers are materials used to extent the range of physical properties, to reduce compound cost, modify physical properties, to reduce compound cost, modify the processing properties and to influence the the processing properties and to influence the chemical resistance of the compound.chemical resistance of the compound.

The effect of a filler on rubber depends on-The effect of a filler on rubber depends on-• structurestructure• particle sizeparticle size• surface areasurface area• geometrical characteristicsgeometrical characteristics

FILLERSFILLERS

Reinforcing TypeReinforcing Type Carbon Black (listed in Carbon Black (listed in order of increasing order of increasing particle size)particle size)

N220 (ISAF)N220 (ISAF)

N330(HAF)N330(HAF)

N550 (FEF)N550 (FEF)

N762 (SRF-LM)N762 (SRF-LM)

N990 (MT)N990 (MT)

Non-blackNon-black SilicaSilica

Zinc OxideZinc Oxide

Magnesium CarbonateMagnesium Carbonate

Aluminium SilicateAluminium Silicate

Sodium AluminosilicateSodium Aluminosilicate

Magnesium SilicateMagnesium Silicate

Extending TypeExtending Type Calcium CarbonateCalcium Carbonate

Barium SulfateBarium Sulfate

Aluminium TrihydrateAluminium Trihydrate

Talc and SoapstoneTalc and Soapstone

• reinforcing carbon blacks reinforcing carbon blacks • non- reinforcing carbon blacksnon- reinforcing carbon blacks• reinforcing non- blackreinforcing non- black• semi reinforcing non- blacksemi reinforcing non- black• non- reinforcing non- blacknon- reinforcing non- black

• Reinforcing carbon blacksReinforcing carbon blacks Furnace black Furnace black SAF – Super Abrasion FurnaceSAF – Super Abrasion Furnace ISAF – Intermediate Super Abrasion FurnaceISAF – Intermediate Super Abrasion Furnace CFCF - Conductive Furnace- Conductive Furnace SCFSCF - Super Conductive Furnace- Super Conductive Furnace

HAFHAF - - High Abrasion Furnace (Low High Abrasion Furnace (Low structure and high structure) structure and high structure)

FFFF -- Fine FurnaceFine Furnace

FEFFEF -- Fine Extrusion FurnaceFine Extrusion Furnace

GPFGPF -- General Purpose FurnaceGeneral Purpose Furnace

SRFSRF -- Semi Reinforcing FurnaceSemi Reinforcing Furnace

Thermal BlackThermal Black

MT - Medium ThermalMT - Medium Thermal• Channel black Channel black • EPCEPC Easy Processing ChannelEasy Processing Channel• Reinforcing Non- blackReinforcing Non- black

Precipitated silica and fumed silicaPrecipitated silica and fumed silica• Semi Reinforcing Non-blackSemi Reinforcing Non-black

aluminium and calcium silicatesaluminium and calcium silicates

high styrene resins high styrene resins

phenolic resinsphenolic resins

FillersFillers

Selection is based on Selection is based on • ReinforcementReinforcement• CostCost• Processing requirementProcessing requirement• Colour requirementColour requirement• Service requirementService requirement• Any other special requirementAny other special requirement

Compound Designing – Hardness

Polymer HardnessPolymer Hardnessphr required phr required for 1 unit for 1 unit increase in increase in HardnessHardness

NRNR SBRSBR CRCR NBRNBR

37-4037-40 39-4139-41 41-4341-43 42-4442-44

22 1.61.6 1.51.5 Ppt. SilicaPpt. Silica

33 3.33.3 2.22.2 Calcium silicateCalcium silicate

55 4.14.1 4.54.5 Hard clayHard clay

7.97.9 5.65.6 5.05.0 Soft claySoft clay

6.66.6 8.48.4 5.05.0 WhitingWhiting

Compound Designing – HardnessCompound Designing – Hardness

Contd.Contd.

NRNR SBRSBR IIRIIR CRCR PBR PBR NBRNBR EPDMEPDM BlackBlack ASTM ASTM DsgnDsgn

DBPDBP

1.51.5 1.81.8 1.31.3 1.21.2 2.22.2 1.71.7 2.42.4 SAFSAF N110N110 113113

1.71.7 2.02.0 1.51.5 1.31.3 2.52.5 1.91.9 2.72.7 ISAFISAF N220N220 114114

1.91.9 2.32.3 1.71.7 1.51.5 2.82.8 2.12.1 3.03.0 HAFHAF N330N330 102102

2.32.3 2.82.8 2.12.1 1.81.8 3.43.4 2.62.6 3.73.7 FEFFEF N550N550 119119

2.52.5 3.13.1 2.32.3 2.02.0 3.83.8 2.92.9 4.14.1 GPFGPF N660N660 9090

2.82.8 3.43.4 2.52.5 2.22.2 4.24.2 3.23.2 4.54.5 SRFSRF N774N774 7070

2.12.1 2.62.6 1.91.9 1.71.7 3.23.2 2.42.4 3.43.4 HAF-HAF-LSLS

N326N326 7272

SOFTENERSSOFTENERS

Processing aidsProcessing aidsA softener is an ingredient that :A softener is an ingredient that :

1.1. speeds up the rate of polymer breakdown speeds up the rate of polymer breakdown 2.2. helps to disperse the other compounding helps to disperse the other compounding ingredientsingredients3.3. helps to reduce nerve within the compoundhelps to reduce nerve within the compound44 can impart building tackcan impart building tack5.5. improves the processing properties and improves the processing properties and modify the final modify the final compound propertiescompound properties6.6. adjusts the compound cost and reduce power adjusts the compound cost and reduce power

consumption during processing consumption during processing

Mineral petroleum oilsMineral petroleum oils They are available from petroleum industry.They are available from petroleum industry.

paraffinicparaffinicnaphthenicnaphthenicaromaticaromatic

Plasticizers Plasticizers They are of the synthetic type , used where mineral They are of the synthetic type , used where mineral

oils are not compatible with the rubberoils are not compatible with the rubberdibutyl phthalate -DBP dibutyl phthalate -DBP di isobutyl phthalate-DIBdi isobutyl phthalate-DIBdi octyl phthalate - DOPdi octyl phthalate - DOP

**FacticesFactices They are vulcanized vegetable oils used as plasticizers to get They are vulcanized vegetable oils used as plasticizers to get smooth compound in extrusion (brown) & to reduce abrasion smooth compound in extrusion (brown) & to reduce abrasion resistance in products like erasers (white) resistance in products like erasers (white)

PROCESSING AIDSPROCESSING AIDS

COMPOSITIONCOMPOSITION EXAMPLEEXAMPLE FUNCTIONFUNCTIONActivated Dithio-Activated Dithio-bisbenzaldihidebisbenzaldihide

Pepton 44Pepton 44 Peptizer for NRPeptizer for NR

Xylyl MercaptansXylyl Mercaptans RPA-3RPA-3 Peptizer for NR,IR,SBR and Peptizer for NR,IR,SBR and NBR. NBR.

Low-molecular-weight Low-molecular-weight polyethylenepolyethylene

A-C Polyethylene A-C Polyethylene 617A617A

Release agent, LubricantRelease agent, Lubricant

Calcium OxideCalcium Oxide Desical PDesical P DesiccantDesiccant

Aliphatic-naphthenic-Aliphatic-naphthenic-aromatic resinsaromatic resins

Strucktol 60NSStrucktol 60NS Homogenizing agent for all Homogenizing agent for all elastomers.elastomers.

Paraffin waxParaffin wax Release agent, lubricantRelease agent, lubricant

Polyethylene glycolPolyethylene glycol Carbowax Carbowax PEG3350PEG3350

Activator for silica, lubricantActivator for silica, lubricant

Petroleum hydrocarbonPetroleum hydrocarbon PetrolatumPetrolatum Release agent, lubricantRelease agent, lubricant

PROCESSING AIDSPROCESSING AIDS

Selection is based onSelection is based on

Nature of polymerNature of polymer Solubility parameterSolubility parameter Viscosity requirementViscosity requirement Filler dispersionFiller dispersion Processing requirementProcessing requirement Any other special requirementAny other special requirement

ANTI-DEGRADANTSANTI-DEGRADANTS- - They are agents added to rubber to improve They are agents added to rubber to improve ageing properties, resistance to oxygen, ozone, alkali, acid, chemicals etcageing properties, resistance to oxygen, ozone, alkali, acid, chemicals etc

TYPETYPE EXAMPLEEXAMPLE STAININGSTAINING

Hindered PhenolHindered Phenol 2,6 Di-t butyl p-cresol2,6 Di-t butyl p-cresol None to slightNone to slight

Hindered Bis-phenolsHindered Bis-phenols Anti-oxidant 2246Anti-oxidant 2246 None to slightNone to slight

Hindered ThiobisphenolsHindered Thiobisphenols Santowhite CrystalsSantowhite Crystals SlightSlight

HydroquinonesHydroquinones 2,5 di(tert-amyl) hydroquinone2,5 di(tert-amyl) hydroquinone None to slightNone to slight

PhosphitesPhosphites Tri(mixed mono and di-nonyl-Tri(mixed mono and di-nonyl-phenyl) phosphitephenyl) phosphite

None to slightNone to slight

DiphenylaminesDiphenylamines Octylated diphenylamineOctylated diphenylamine Slight to moderateSlight to moderate

NaphthylaminesNaphthylamines Phenyl-alpha-naphthylaminePhenyl-alpha-naphthylamine ModerateModerate

QuinolinesQuinolines Polymerized 2,2,4, tri-methyl Polymerized 2,2,4, tri-methyl 1,2-dihydroquinoline1,2-dihydroquinoline

Slight to moderateSlight to moderate

Carbonyl-amines Carbonyl-amines condensation productcondensation product

Reaction product of Reaction product of diphenylamine and acetonediphenylamine and acetone

ConsiderableConsiderable

Para-phenylene diaminesPara-phenylene diamines Mixed Diaryl-p-phenylene Mixed Diaryl-p-phenylene diaminesdiamines

Considerable to severeConsiderable to severe

ANTI-DEGRADANTSANTI-DEGRADANTS

Selection is based onSelection is based on

Type of protection desiredType of protection desired Environment in which the product is exposed.Environment in which the product is exposed. Chemical activityChemical activity Persistence (volatility and extractability)Persistence (volatility and extractability) Nature of end useNature of end use Discolouration and stainingDiscolouration and staining ToxicologyToxicology CostCost

OTHER MATERIALSOTHER MATERIALS

PeptizersPeptizers : They speed up the rate of polymer break down and : They speed up the rate of polymer break down and also control the speed of breakdown, decreasing nerve within the also control the speed of breakdown, decreasing nerve within the compound and shrinkage during subsequent processing.compound and shrinkage during subsequent processing.

penta chloro thiophenolpenta chloro thiophenol Renacit VIIRenacit VII

RetardersRetarders : They help to increase the scorch time (premature : They help to increase the scorch time (premature vulcanization) but do not interfere with the vulcanizationvulcanization) but do not interfere with the vulcanization

cyclohexyl thiophthalimide (CTP)cyclohexyl thiophthalimide (CTP) Santogard PVISantogard PVI

StiffenersStiffeners : Stiffeners are used to improve the plasticity of the : Stiffeners are used to improve the plasticity of the compound in very small quantities.compound in very small quantities.

dihydrazine sulfatedihydrazine sulfate

Flame retardantsFlame retardants

Chemicals which can improve the flame retardency Chemicals which can improve the flame retardency of the compoundof the compound

highly chlorinated paraffins and waxes, antimony oxide, highly chlorinated paraffins and waxes, antimony oxide, aluminium oxide and selenium aluminium oxide and selenium

Colors and pigmentsColors and pigments They provide esthetic look and appearance for the product They provide esthetic look and appearance for the product

[organic and inorganic] [organic and inorganic] Tackifying agentsTackifying agents

They are useful in providing tackiness to the compound.They are useful in providing tackiness to the compound.

wood rosin, coumarone resins, pine tar.wood rosin, coumarone resins, pine tar.

Blowing agentsBlowing agents They are materials which provide either open or They are materials which provide either open or

closed cell structure by producing CO2 or nitrous closed cell structure by producing CO2 or nitrous gases during vulcanization gases during vulcanization

dinitroso pentamethylene tetramene (DNPT)dinitroso pentamethylene tetramene (DNPT) azocarbonamide (ADC)azocarbonamide (ADC) baking soda (sod.bicarbonate)baking soda (sod.bicarbonate)

Bonding agentsBonding agents They facilitate adhesion between rubbers, fibers, fabrics, They facilitate adhesion between rubbers, fibers, fabrics,

metalsmetals chemlok, resorcinol – formaldehyde- latex for dipping of chemlok, resorcinol – formaldehyde- latex for dipping of

nylon cords in tyre manufacturenylon cords in tyre manufacture ReordantsReordants They are basically perfumes added to mask odors of rubber They are basically perfumes added to mask odors of rubber

during processing and service life of rubber.during processing and service life of rubber. Bactericides / fungicidesBactericides / fungicides to resist microbial agents to resist microbial agents

STEPS OF COMPOUND DEVELOPMENTSTEPS OF COMPOUND DEVELOPMENTModification of existing compound with respect toModification of existing compound with respect to

Cost/priceCost/price ProcessingProcessing PerformancePerformance

New compound developmentNew compound development

Set specific objectives (properties, processing, price etc)Set specific objectives (properties, processing, price etc) Select best polymerSelect best polymer Study test data of existing compoundsStudy test data of existing compounds Survey compound formulations.Survey compound formulations. Choose starting formulation.Choose starting formulation. Develop compound in the laboratory to meet objectives.Develop compound in the laboratory to meet objectives. Estimate cost of the compound.Estimate cost of the compound. Evaluate processability in factoryEvaluate processability in factory Use compound to make a product sample.Use compound to make a product sample. Test product sample against performance specification.Test product sample against performance specification.

The mixThe mix RubberRubber 100100 Vulcanizing agentVulcanizing agent 0.3 - 3.50.3 - 3.5 Accelerator/sAccelerator/s 0.5 – 1.50.5 – 1.5 ActivatorActivator 2.5 – 5.02.5 – 5.0 Antidegradents Antidegradents 1 - 21 - 2 Fillers Fillers As requiredAs required

SoftnerSoftner 5 - 105 - 10 Other materials when necessaryOther materials when necessary As requiredAs required

STAGES OF PRODUCT DEVELOPMENTSTAGES OF PRODUCT DEVELOPMENT : :Compound Design,

Lab Evaluation,

Shop floor processing trials (mixing, moulding,extrusion, calendaring, fabrication of product, curing, etc ),

Analysis of feedback ,

Compound Modification (if reqd.),

Testing of processing properties and of finished product,

Field trials,

Validation of manufacturing process.

MIXINGMIXING

Compound properties & batch to batch consistency depends Compound properties & batch to batch consistency depends on :on :

Compounding formulation design,Compounding formulation design, Raw materials Quality, Raw materials Quality, Effects of Further Processing,Effects of Further Processing,

Rework blending (Rework Quality & Quantity)Rework blending (Rework Quality & Quantity) Rubber processing equipments available & their Rubber processing equipments available & their condition.condition. The knowledge of Raw Materials used & their behavior during The knowledge of Raw Materials used & their behavior during

mixing and further processing is essentialmixing and further processing is essential

MIXING MIXING

Mixing Process is the base of Rubber Product Manufacturing Mixing Process is the base of Rubber Product Manufacturing Technology.Technology.

The success of subsequent processing & finished product The success of subsequent processing & finished product quality depends entirely on the quality & batch-to-batch quality depends entirely on the quality & batch-to-batch consistency of the mixed compounds.consistency of the mixed compounds.

‘‘Mixing’Mixing’ deals in deciding: deals in deciding: What equipment to use (speeds, pressures, temperature, time What equipment to use (speeds, pressures, temperature, time

cycles, procedures, etc. to blend the selected compounding cycles, procedures, etc. to blend the selected compounding ingredients into a properly mixed compound.ingredients into a properly mixed compound.

How to achieve High Degree of Dispersion and batch to How to achieve High Degree of Dispersion and batch to batch consistency.batch consistency.

MIXING

• Mixing process can be sub-divided into three stages :

1) Feeding ingredients to mixer (correct quantities at correct times at correct temperature.),

2) Actual Mixing of the ingredients,

3) Discharge of mixed compound and its shaping, cooling, packaging and storage for the next

process.

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MIXING Five main steps involved in the Mixing Operations :

1.1. Sub DivisionSub Division Of larger lumps & aggregates,Of larger lumps & aggregates,

2. 2. IncorporationIncorporation Of powders or liquidsOf powders or liquids

3. 3. DispersionDispersion Involves reduction of the size of agglomerates,Involves reduction of the size of agglomerates,

4. 4. Simple MixingSimple Mixing Involves moving particles from one point to another.Involves moving particles from one point to another.

5. 5. Viscosity ReductionViscosity Reduction By breakdown of the polymer and transforming it to By breakdown of the polymer and transforming it to desired viscosity.desired viscosity.

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• A good Dispersion rating requires :

High Shear Stress (i.e. High mix viscosity),

High Filler Loading,

Polymers of not too low viscosity,

Low Mixing temperatures,

Charging oils at the end of mixing cycle.

MIXING

• During Dispersive mixing, the carbon black agglomerates are broken down to less than 1 micron size.

• Dispersion largely depends on shear stress ( a critical value of shear stress is necessary to breakdown the agglomerates below which no dispersion action will take place).

40

41

• To avoid scorching of compound; a two stage mixing procedure is used.

• Stage 1 - carbon black and other non vulcanizing

additives are combined with the raw rubber and

Higher mixing temperatures up to 160°C are used.

[The term Master Batch is used for first stage mixture]

• Stage 2 - After stage 1 mixing has been completed, and time for cooling has been allowed; stage 2 mixing is carried out in which vulcanizing agents are added. Lower mixing temperatures 90-100 °C are used.

Two-Stage Mixing in Internal Mixers

[The term Final Batch is used for second stage mixture]

MIXING

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NR Mastication & Blending NR+SR

• Mastication of NR to Optimum Degree and proper blending of Synthetic Rubbers with NR is Very Important .

• Ingredients which are difficult to disperse (e.g. hard carbon blacks, Ppt. silica, ZnO, etc) require Higher stock viscosity to disperse well.

Stock Viscosity Control is achieved through:

Compounding formulation design,

Close temperature control during mixing operations,

Use of specific sequence for addition of ingredients ,

Remixing of the stock after cooling.

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• Raw NR is dry & tough (Mooney Viscosity at 100°C > 80) and has to be masticated to a Workable Level of Mooney Viscosity of 50 to 60.

• Most Synthetic Rubbers are produced to a tailored Mooney viscosity (range 50 – 60) and hence ‘Mastication’ is not necessary.

• Keep Lower Mastication Temperatures when a Two-Roll mill is used (say, 60-70°C).

• Viscosity of Masticated NR should be closer to the Synthetic Rubber to be blended with it.

• NR-BR blends require higher shear rates for proper blending and hence Banbury / Intermix are more suitable than a mixing mill.

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EFFECT OF MASTICATION TEMPERATURE ON MOONEY VISCOSITY OF NREFFECT OF MASTICATION TEMPERATURE ON MOONEY VISCOSITY OF NR

MILLING MILLING TIME, MINTIME, MIN

MOONEY VISCOSITY (ML1+4 @ 100°C, UNITS)MOONEY VISCOSITY (ML1+4 @ 100°C, UNITS)

WITHOUT PEPTIZER WITHOUT PEPTIZER WITH PEPTIZER (DBD=0.5 PHR)WITH PEPTIZER (DBD=0.5 PHR)

@ 70°C@ 70°C @ 100°C@ 100°C @ 70°C@ 70°C @ 100°C@ 100°C

00 9595 9595 9595 9595

33 7676 8585 5858 5656

66 5757 8383 4040 4040

99 4747 6868 3333 2828

1212 4545 6565 3030 2424START TEMPERATURE, START TEMPERATURE, MOONEY VISCOSITY (ML1+4 AT 100°C), UNITSMOONEY VISCOSITY (ML1+4 AT 100°C), UNITS

OPEN MILL OPEN MILL (TIME = 8 MIN)(TIME = 8 MIN)

70 70 °C°C

100 100 °C°C

PEPTIZER = 0PEPTIZER = 0

5555

7575

PEPTIZER = 0.25PEPTIZER = 0.25

4242

4242

PEPTIZER = 0.5PEPTIZER = 0.5

3636

3737

INTERNAL MIXER INTERNAL MIXER (TIME 4 (TIME 4 MIN)MIN)

150 150 °C°C

160 160 °C°C

9090

8888

5454

4848

4242

3636

45

Mixing Mixing Time, Time, MinMin

Mixer Speed 25 rpmMixer Speed 25 rpm Mixer Speed 50 rpmMixer Speed 50 rpm

No Peptizer No Peptizer 0.1 Phr PCTP0.1 Phr PCTP No PeptizerNo Peptizer 0.1 Phr PCTP0.1 Phr PCTP

ML1+4@100°CML1+4@100°C ML1+4@100°CML1+4@100°C ML1+4@100°CML1+4@100°C ML1+4@100°CML1+4@100°C

00 9090 9090 9090 9090

22 7474 6969 6969 5252

44 68.568.5 6060 5050 3737

66 6767 5656 4242 2929

88 6565 5353 3434 --

1010 6161 5050 -- --Note the rapid reduction of Mooney viscosity at higher rotor speeds in the presence of chemical Peptizer at a very small dosage.

46

Effects of “Under Mastication” of NR

• Lower Mixing Cycles,

• High heat build up during mixing and subsequent steps,

• Poor extrudability / calendaring properties of the stock,

• Excessive shrinkage & dimensional control problems with extrudates / calendared stocks.

• Scorchy compounds.

• Excessive porosity in extrudates,

• Difficulties with ‘Rework’ blending,

47

Effects of “Over Mastication” of NR Lower shrinkage of extrudates / calendared sheets,

• Lower die swell & loss of dimensional control,

• Increased curing defects in finished products due to excessive flow and air entrapment,

• Compounded sheets stick to each other during storage and sagging of sheets,

• Excessive surface tack due to poor green compound strength,

• Loss of dynamic, tensile & tear strength properties of the vulcanizate,

• Changes in the viscosity of solvent based solutions & loss of surface tack.

48

MIXING

49

PROBLEMS & REASONSPROBLEMS & REASONS

PROBLEMSPROBLEMS REASONSREASONS

Poor DispersionPoor Dispersion

Batch size not optimized, mixing time is lower, filler Batch size not optimized, mixing time is lower, filler addition time not proper, insufficient ram pressure, poor addition time not proper, insufficient ram pressure, poor temp. control, poor / inconsistent raw material quality, temp. control, poor / inconsistent raw material quality, excessive moisture content in polymer and fillers, under / excessive moisture content in polymer and fillers, under / over mastication of NR.over mastication of NR.

Batch to Batch Batch to Batch VariationsVariations

Variation of start temp., variation in dump time and / or Variation of start temp., variation in dump time and / or temp. , poor dispersion, variation in ram pressure, temp. , poor dispersion, variation in ram pressure, variation in polymer / filler/ oil quality / rework quality, variation in polymer / filler/ oil quality / rework quality, under / over mastication of NRunder / over mastication of NR

Poor ProcessabilityPoor Processability

Compound viscosity not within controlled limits, under / Compound viscosity not within controlled limits, under / over mastication of NR, Processing temp. not under over mastication of NR, Processing temp. not under control, poor dispersion, higher loading of plasticizer / control, poor dispersion, higher loading of plasticizer / tackifiers / fillers/rework.tackifiers / fillers/rework.

Manufacturing processManufacturing process Unvulcanized rubber, whether natural or synthetic Unvulcanized rubber, whether natural or synthetic

behaves as a viscoelastic fluid during mixing. It is the behaves as a viscoelastic fluid during mixing. It is the operation required to obtain a thorough and uniform operation required to obtain a thorough and uniform dispersion of all ingredients called for by the formulae dispersion of all ingredients called for by the formulae in the rubberin the rubber

MachineryMachinery

2-roll mixing mill2-roll mixing mill

kneaderkneader

internal mixers internal mixers

Continuous, automatic high speed mixingContinuous, automatic high speed mixing

2 –ROLL MIXING MILL

KNEADER

Two Roll Mill with stock blender & individual roll drives

53

54

F 270 Banbury Mixer K 6A INTERMIX

55

Capacities: Banbury MixersCapacities: Banbury Mixers

BanburyBanburyMixerMixer

Mixer Mixer ChamberChamber

Net Volume,Net Volume, ltrltr

Approx. Approx. Batch Wt *Batch Wt *

kgkg

Mixing Mixing SpeedSpeedRange,Range, RPMRPM

Torque rating Torque rating kW / RPMkW / RPM Approx. Approx.

MachineMachineWeight, MTWeight, MTCompact Compact

DriveDriveUniUni

DriveDrive

F 50F 50 5050 5050 40 - 12040 - 120 2.22.2 4.64.6 13.213.2

F 80F 80 8080 6060 30 - 10530 - 105 3.73.7 6.36.3 16.116.1

F 120F 120 120120 9090 30 - 9030 - 90 5.65.6 9.09.0 19.519.5

F 160F 160 160160 120120 20 - 8020 - 80 7.57.5 12.012.0 30.230.2

F 200F 200 200200 165165 20 - 6020 - 60 8.98.9 12.712.7 30.530.5

F 270F 270 270270 202202 20 - 6020 - 60 13.113.1 24.624.6 43.043.0

F 370F 370 414414 310310 20 - 6020 - 60 -- 37.337.3 54.054.0

F 440F 440 438438 330330 20 - 6020 - 60 -- -- --

F 620F 620 672672 500500 20 - 5020 - 50 -- 52.252.2 110.5110.5

( * Fill factor = 75% , S.G. = 1.0 )

56

Capacities: IntermixCapacities: Intermix

IntermixIntermix

Mixer Mixer ChamberChamber

Net Volume,Net Volume, ltrltr

Approx. Approx. Batch WtBatch Wt

kgkg

Mixing Speed, RPMMixing Speed, RPM Motor HPMotor HP

1-Speed , 2-Speed 1-Speed , 2-Speed

MachineMachineWeight, Weight,

MTMTSingle SpeedSingle Speed Two SpeedTwo Speed

K 0K 0 1.81.8 1.261.26 7676 75 / 15075 / 150 5, 5 / 105, 5 / 10 5.65.6

K 1K 1 5.55.5 3.93.9 40 / 14540 / 145 Variable driveVariable drive 5050 2020

K 2K 2 2020 1414 3030 22 / 4422 / 44 50. 50 / 10050. 50 / 100 5050

K 2AK 2A 4949 3434 3333 22 / 4422 / 44 150 , 75 / 150150 , 75 / 150 6060

K 4K 4 9191 6464 3333 22 / 4422 / 44 220, 50 / 300220, 50 / 300 9898

K 5K 5 143143 100100 3333 22 / 44322 / 443 300, 200 / 400300, 200 / 400 140140

K 6K 6 206206 144144 3333 22 / 4422 / 44 475, 320 / 640475, 320 / 640 235235

K 6AK 6A 257257 180180 3333 22 / 4422 / 44 500, 350 / 700500, 350 / 700 280280

K 7K 7 310310 217217 3333 22 / 4422 / 44 750, 500/1000750, 500/1000 310310

K 8K 8 498498 349349 3333 22 / 4422 / 44 -- --

( * Fill factor = 70% , S.G. = 1.0 )

Dry rubber based productsDry rubber based products

Mix and Compound DesignMix and Compound Design

For manufacture of dry rubber products, the For manufacture of dry rubber products, the following minimum process steps are essentialfollowing minimum process steps are essential

compoundingcompounding shapingshaping vulcanization vulcanization

MIXING PROCEDUREMIXING PROCEDUREWeighing compounding ingrediants as per

formulation

Mastication

Compounding And Homogenisation

Maturation

Prewarming

Blank preparation

DRY RUBBER PRODUCTS MANUFACTURE

RUBBERCOMPOUNDIN

GCHEMICALS

MATURATION

PRE-WARMING

TESTING& QC

MOULDED GOODS EXTRUDED GOODS CALENDERED GOODS

MOULDED GOODS EXTRUDED GOODSCALENDARED

GOODS

BLANK PREPARATION

MOULDING (HYDRAULIC

PRESS)

PACKING AND DESPATCH

AUTO CLAVE OR

OVEN

FINISIHING OPERATION AND QUALITY CONTROL

VULCANISATION