may 13, 2015cancarb 1. may 13, 2015cancarb 2 thermax ® thermal carbon black thermax ® vs. furnace...

April 18, 2023Cancarb1


• Thermax® Thermal Carbon Black

• Thermax® vs. Furnace Black

• The Thermax Advantage• Natural Rubber • Nitrile Rubbers• Hydrogenated Nitrile• Polychloroprene• Fluoroelastomers• NBR/PVC Blends• Ethylene Propylene Rubbers• Chlorosulfonated Polyethylene Rubbers – CSM• Butyl and Halobutyl Rubbers

• Questions & Answers

Overview


• Carbon black can be broadly defined as very fine particle aggregates of carbon, possessing an amorphous quasi-graphitic molecular structure

• The most significant areas of distinction between thermal black and furnace black are particle size and structure

• Thermax®, thermal carbon black, due to its higher particle size (280 nm) and lower structure, compared to even the most coarse furnace black, can be translated into excellent rubber compound properties

Thermax®


Particle Size Diameter

N110(15nm)

N762(80nm)

N990(280nm)

Thermax® vs. Furnace Black Grades


Low Structure Moderate Structure High Structure

N990 N762 N550

Thermax® vs. Furnace Black Grades


N762N774

N539

N660

N326

N330

N339

N343 N121

N220 N110

N990

N650 N550

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

NITROGEN SURFACE AREA (m2/g)

DECREASING PARTICLE SIZE

OA

N (

DB

P)

AB

SO

RP

TIO

N (

ml/

10

0g

)

INC

REA

SIN

G S

TR

UC

TU

RE

The Carbon Black Spectrum


Rubber PropertyAs Particle size

IncreasesAs Structure Decreases

Mixing temp.

Dispersion

Viscosity

Green Strength

Extrusion Quality

Scorch Safety

Influence of Carbon Black on Properties


Rubber PropertyAs Particle size

IncreasesAs Structure Decreases

Tensile

Elongation

Hardness

Tear resistance

Compression set

Heat build up

Abrasion resistance

Resilience

Influence of Carbon Black on Properties


The properties of Thermax® can be translated into rubber compounds with:

• Lower heat build-up, especially during extrusion, which is very important for halogen bearing rubbers and high hardness compounds

• Low hysteresis loss in dynamic applications, for example; automotive engine mounts

• Reduced volume swell in aggressive fluids

• Reduced cost

• Low compound viscosity which is essential for injection molded and sponge compounds

The Thermax® Advantage


– CH2 – C = CH – CH2 –

-CH2 CH2-

CH3 H

C=C

Natural Rubber Structure

CH3

• Natural rubber is polyisoprene

• There are four possible isomers of natural rubber

cis–1,4 Isomer

• 1,4 structure means that ‘C’ atoms 1 and 4 are joined in forming the chain

• In the cis-1,4 structure both carbon atoms 1,4 forming the chain are on the same side of the double bond

Natural Rubber (NR)


• Natural Rubber has outstanding mechanical properties and fatigue resistance making it a very popular choice in dynamic applications

• Natural rubber consists of polymer chains all having almost 100% perfect cis–1,4 structure. The true chemical name for this polymer is in fact, cis-1,4-polyisoprene

• When the units in a macromolecule all consist of the same molecule, the polymer is said to be stereo regular

Natural Rubber (NR)


Natural Rubber:• Crystallizes on stretching, resulting in:

• high gum tensile strength• high tensile strength/elongation @ break• very high tear strength & hot tear resistance• excellent De Mattia cut growth resistance

• Gives a glass transition temp (Tg) of approximately -75°C

• Has high resilience

• Has excellent tack & green strength properties• Imparts low damping (hysteresis) and low heat build-up in

dynamic deformation

• Is unsaturated (double bonds), resulting in poor resistance

to:• Heat aging• Ozone• Oils and hydrocarbons

Properties of Natural Rubber (NR)


Common Applications of Natural Rubber are:

• Truck tire tread (Tear, hot tear, low heat build-up)

• Passenger radial (Flexibility, low heat build-up)

• Anti-vibration (Dynamic deformation)

• Conveyor belting (High mechanical properties, tear)

• Adhesive tapes and solutions (Tack)

Applications of Natural Rubber


• Thermax® maintains the inherent good dynamic properties of the natural rubber polymer• The best choice for anti-vibration applications

• Thermax® lowers compound hardness while retaining the good tack properties inherent to natural rubber• Excellent for cushion gum compounds

• In wiper blade applications, higher loadings of Thermax® lower the rubber content of the compound which is essential for low noise and a good surface finish.

The Thermax® Advantage in Natural Rubber Compounds


SMR 100 100Zinc Oxide 3 3Stearic acid 1 1A.O. TMQ 1.5 1.5N 762 15 15Thermax N990 45 70Aromatic Oil 15 15CBS 3 3TMTD 0.5 0.5Sulfur 0.5 0.5

Cure time @ 160°C 11‘ 11‘Hardness 43 49Tensile strength 206 178Elongation @ Break % 535 480

Dynamic testing at 20 Hz Tan Delta at 25°C 0.084 0.027

Natural Rubber Engine Mount

NR Compound Example Using Thermax®


Nitrile Structure

Nitrile Rubber (NBR)

- CH2 - CH = CH - CH2 -

CN

acrylonitrilebutadiene

Polymer Unit

- CH2 - CH -+

( ) - (CH2 - CH = CH - CH2)n -

CN

CH2 - CH

m

-


• Nitrile rubbers are high molecular weight copolymers of 1,3-butadiene and acrylonitrile

• The percentage of acrylonitrile content can be varied from 18% to 50%, and will influence the performance characteristics of the polymer

• The great variation in acrylonitrile content possible with nitrile rubber, allows for compounds to be customized to highlight specific required properties

Nitrile Rubber (NBR)


Heat – aging resistance

Abrasion resistance

Tensile

Stiffness

Thermoplasticity

Compatibility with polar polymers

Oil/fuel resistance

Cure rate – Sulphur Cure System

Processability

Density

Increases

Air/gas permeability

Low temperature flexibility

Cure rate – peroxide system

Resilience

Decreases

Nitrile Rubber – Effect of Acrylonitrile Content

As ACN Increases


Decreases

Compression set

Porosity

Modulus

Green strength

Mill shrinkage

Sheet formation time on mill

Mixing temp

Acceptance of fillers/plasticizers

Incorporation time of fillers

Increases

Nitrile Rubber – Effect of Mooney

As Mooney Increases


Nitrile Rubber:

• Has very good oil and fuel resistance

• Can perform over a wide temperature range

• Has inherently good resistance to gas permeation which increases as the level of acrylonitrile increases

• Can be blended, up to 50%, with polyvinyl chloride (PVC) to produce compounds that exhibit good weathering characteristics in addition to good dynamic properties

• Can be co-polymerized with methacrylic or acrylic acid to produce carboxylated nitrile (XNBR), which is noted for its excellent dynamic properties and abrasion resistance

Properties of Nitrile Rubbers


Common Applications of Nitrile Rubber are:

• Gaskets and seals – NBR, XNBR (for high hardness)

• Hoses – NBR (mainly in tubes), NBR/PVC (mainly in covers)

• Belting – NBR

• Rollers – NBR, XNBR (for high hardness)

• Cable Jackets – NBR/PVC

• Textile (spinning cots/aprons) – NBR, NBR/PVC, XNBR

• Industrial footwear – NBR, NBR/XNBR blend, NBR/PVC sponge

• Insulation – NBR/PVC sponge

• Molded/extruded components for various industries & automotive

• Fabric proofing – NBR

• Milking inflation - NBR

Applications of Nitrile (NBR)


• Higher loadings are achievable with Thermax®, which reduces the rubber content enabling for lower swell in aggressive fluids• Gaskets and seals

• Thermax® promotes good extrusion properties and low heat development, avoiding potential scorch problems. This is critical for high hardness compounds• Hydraulic hose tubing

• Thermax® maintains the desired hardness of a compound while lowering the viscosity for effective blowing• NBR/PVC Sponge Insulation, hoses and soles

The Thermax® Advantage in NBR Compound Applications


Nitrile Rubber 100 (33-34% ACN, 75-80 Mooney)ZnO 5St. acid 1Processing Additive 2A.O. Aminox 2 (DPA + Acetone reaction product)A.O. ZMBI 2 (Zn Salt of 2 – Mercaptobenzimidazole)N550 50 Suitable blend for good processing,

N990 50 vulcanizate properties and good heat ageing Paraplex G-25 10 KP 140 10 Sulfasan R 1CBS 3TMTD 3Cure @ 166° 15'SH / TS / EB 70 / 152 / 270Vol. swell % 19 (ASTM Oil 3 / 70h 135°C)

Blending with Thermax N990 helps improve scorch safety during extrusion due to lower heat development. Higher filler loading improves over all extrusion properties and sealing with end couplings

Hydraulic Hose (Broad Temperature Range)

Blend of polyester and phosphate plasticizers for resistance to heat extraction and low temperature cracking

Nitrile Compound Example Using Thermax®

>>


HNBR Range

% Hydrogenation % ACN content Mooney (ML 1+4 @ 100°C) ~ 85 to 99+ 17 to 50 50 to 150

Hydrogenated nitrile rubber is based on NBR that has been chemically altered (hydrogenated), resulting in a much lower amount of unsaturation in the polymer backbone. HNBR exhibits significantly improved heat resistance, compared to NBR, while retaining excellent oil and fuel resistance.

Hydrogenated NBR (HNBR)


Mooney (ML 1+4 @ 100°C) 43 86

Hardness (Shore A) 68 76

T.S. (M.Pa) 17.5 21.9

EB (%) 390 180

Tear Die C (KN/m) 15 16.7

Comp. Set % (168h/150°C) 18 27

Abrasion (DIN mm3 loss) 145 260

Air Ageing (168h/150°C)

Hardness +8 +17

T.S. (%) Nil Brittle

EB (%) -30 Brittle

The significant improvements in the properties of HNBR over NBR, especially in compression set & heat ageing, bring HNBR very close to specialty rubbers.*ML 1+4@125oC

**ML 1+4@100oC

NBR+ 50 phr FEF 99+ % hydrogenation

38% ACN 55* Mooney

38% ACN50** Mooney

Comparison with NBR for 50 phr FEF compound-Peroxide cured

HNBR+ 50 phr FEF


HNBR* ACM FKM VMQ

Tensile 1 3 3 7

Heat Resistance 3 3 1 1

Comp. Set 2 2 1 1

Low Temp 3 5 7 1

Gear Oil 1 1 4 7

ASTM Oil #1 1 3 4 7

Sour Gasoline 2 5 1 7

Rating:1 Best; 7 Worst

*99+ % Hydrogenation

Hydrogenated NBR (HNBR)


• Timing belts (automotive) – ozone resistance, flexing • Power steering rotary shaft seals

• ‘O’ rings

• Oil well specialties

• Rollers

• Air conditioning hoses for cars

Applications of HNBR


• HNBR rubbers have inherently good mechanical properties and do not require a reinforcing black. Thermax® maintains the good mechanical properties of HNBR while lowering the compound viscosity which is essential for easy processing

• Thermax® does not degrade the excellent compression set of the HNBR polymer

• Higher loadings are possible with Thermax® resulting in lower polymer content which provides lower oil swell and a significant reduction in the overall compound cost

• Thermax® allows for extrusion with lower heat build-up giving better scorch safety and further improved impermeability of HNBR

The Thermax® Advantage in HNBR Compounds Applications

TORNAC A 38.55 (99.5% saturation) 100Thermax® N990 50Plasticizer WB 300* 5ZnO 5Stearic acid 1Trigonox 101-45** 8TAIC 3ML 1+4 @ 100°C 70MS Mooney Scorch at 125°C >25 ‘Cure time at 180°C 9’SH/TS/EB 60/146/235Air aging 150°C / 168H +8/-3/-40%Compression Set 70 h / 150°C 12

Thermax® maintains good low compression viscosity/mold flow, allows for less polymer content, low swell, adequate tensile strength and excellent compression set*Mixture of Aliphatic / Aromatic polyesters

** 2,5 dimethyl – 2,5 bis (tert butyl peroxy) hexane (Akzo).

Low Compression Set HNBR SealHNBR Compound Example Using Thermax®


Low Compression Set Seal

NBR/PVC Blends

• Both NBR and PVC are polar which makes them very compatible, typically a 70/30 ratio

• NBR provides resistance to heat and organic fluids but has poor resistance to weathering and ozone due to unsaturation.

• PVC provides resistance to weathering, ozone and aliphatic hydrocarbons oils

• PVC also improves processing, reduced flammability and mechanical properties such as T.S., tears and abrasions


Carboxylated NBR (XNBR)

• Carboxylated NBR (XNBR) is a terpolymer NBR with acidic organic monomer (typically 1 & 7%) carboxylic acid as a third monomer

• Reactions of ZnO and Carboxylic Acid result in a matrix with significantly increased mechanical properties, such as higher hardness, abrasion resistance and tear strength

• Although sacrifice in processing (mill and mould sticking) scorch, resilience and low temperature resistance, product retains the basic properties of NBR (oil & fuel resistance)


Applications

• Gasket and Seals - mainly NBR, high hardness seals ex/ Mud Pump – XNBR

• Hoses – NBR mainly in tubes, NBR/PVC bend mainly in cover

• Beltings• Rollers – NBR, XNBR for higher hardness rollers• Cable Jackets – NBR/PVC blends• Textile – spinning cots/aprons, NBR, NBR/PVC, XNBR• Industrial Footwear – NBR, NBR/XNBR blend, NBR/PVC

sponge soiling• Insulation – NBR/PVC sponge• Moulded/extruded components for various industries,

automotive• Fabric proofing – protective coatings, NBR• Milking inflation – NBR, resistance to fat


NBR/PVC Blend Example Using Thermax®

NBR/PVC Blend70/30 100 100Sulphur 1.5 1.5ZnO 5 5St. acid 1.5 1.5 N550 25 30Thermax® N990 45 60DOP 23 30 A.O. ODPA 1.5 1.5 P. Wax 3 3 TMTM .5 .5ML, 1+4@ 100°C 34 34MS, t5 @125°C 23’ 22’Cure Time @ 160°C 7.5’ 7.5’SH/TS/EB 68/143/450 70/131/415 Comp. set 22 h/70°C 27 27 Ageing in M15 test fuel (FAM 85 – Methanol 15), 48h at 23°CChange -18/-59/-60/+47.8v -19/-27/-51/+39v

High loading of Thermax® lowers the polymer content allowing for low swell in aggressive fuels, low compression set and good extrusion.

Gasohol Resistant Hoses Compound 1 Compound 2



Polychloroprene Structure

-CH2 H CH2 = C – CH = CH2

C=CCl

Cl CH2-

Chloroprene (liquid)

trans-1,4 polychloroprene (88-92 %) 2-chlorobutadiene

Similar to trans-1,4 isoprene but, the ‘CH3’ group has been replaced by ‘Cl’

Polychloroprene (CR)


• Polychloroprene is often called neoprene. Neoprene is, in

fact, the trade name of Dupont Dow Elastomers polychloroprene product line

• Polychloroprene has a structure similar to that of natural rubber except one of the methyl side groups is replaced by a chlorine atom and it is a trans-oriented molecule

• Polychloroprene can be sulfur modified or mercaptan modified to provide specific desired properties

Polychloroprene (CR)


Polychloroprene Rubber:

Crystallizes on stretching, allowing for:• High gum tensile strength; similar to Natural Rubber (NR)• Very good fatigue resistance

• When sulfur modified, will provide:• Excellent fatigue resistance• Highly resilient compounds• High tear resistance

• When mercaptan modified, will provide:• Better raw polymer stability• Good resistance to heat• Good resistance to compression set

Properties of Polychloroprene (CR)


Common applications of polychloroprene rubber are:

• Adhesives – polarity-bonding

• V-belts – tack and fire resistance

• Timing belts – tack and fire resistance

• Bellows – high flexibility

• Automotive seals

• Bridge bearing pads – good dynamic properties and ozone resistance

• Wire and cable – resistance to abrasion, oil, flame and weathering resistance

• Hose (especially covers) – good weathering resistance

Applications of Polychloroprene


• Thermax® will not degrade the inherently good mechanical properties of polychloroprene

• Thermax® lowers the compound viscosity which is essential for lower heat build-up during extrusion and good mold flow

• Thermax® will maintain the good compression set of the polychloroprene rubber

• Higher loading of Thermax® is possible resulting in a lower rubber content which decreases oil swell and reduces the compound cost

The Thermax® Advantage in Polychloroprene Rubber Compounds

Neoprene WRT 60SMR CV 60 40ZnO 5MgO 4Stearic acid 2Thermax® N990 40SRF 20Paraffinic Oil 2-3DPG 0.5TMTD 0.5Sulfur 1.06 PPD 1.5TMQ 1.5MC Wax 2Hardness 60

High loading of Thermax® reduces the polymer content (cost savings) which helps for low noise and gives a “clean” product & surface finish

Wiper Blade Compound

Polychloroprene Compound Example Using Thermax®



Fluoroelastomer Structure

- (CF2-CH2)X - (CF-CF2)Y - (CF2-CF2)Z

CF3

VF2

VinylidineFluoride

HFPHexafluoropropylene

TFETetrafluoroethylene

Fluoroelastomers (FKM)


• Fluorocarbon elastomers are a very popular choice for difficult sealing applications

• Fluoroelastomers are created by substituting fluorine for hydrogen on a carbon-based macromolecule

• Unlike hydrocarbon rubbers, which are non-polar, the presence of fluorine creates polar molecules

• Fluoroelastomers are expensive and difficult to process due to their relatively high molecular weight

Fluoroelastomers - FKM


Fluoroelastomers:

• Can be compounded to provide high heat resistance and thermal

stability

• Have excellent oil & gasoline resistance

• Have excellent hydrocarbon-based solvent resistance

• Have very good impermeability

• Are flame resistant

• Are resistant to weathering

• Have excellent compression set resistance

• Are expensive

• Tend to have high Mooney viscosities which accelerate heat build-up when mixing

Properties of Fluoroelastomers


Common applications of Fluoroelastomers are:

• Automotive – Valve Stem Seals, Shaft Seals, ‘O’ Rings

• Aerospace – ‘O’ Rings for Hydraulic, Lubricating and Fuel Systems

• Oil Field – Packers & Blow-out Preventers

• Industrial – Expansion Joints in Mines, Gaskets, Valve & Pump Linings

• Hoses – Fuel Lines, Turbo Chargers, Bio-diesel

Applications of Fluoroelastomers


• High loadings of Thermax® will not reduce the excellent compression set and low swell inherent to FKM• Excellent for ‘O’ ring and seal applications

• The higher loading ability of Thermax® improves the impermeability of the compound• The best choice for fuel line hose veneer

• The specific gravity of Thermax® is similar to that of FKM, so higher loading of Thermax allows for the same volume of compound to be produced while using less of the expensive FKM elastomer, without sacrificing the desired compound properties.• Overall compound cost reduction

The Thermax® Advantage in FKM Compound Applications

FKM Compound Example Using Thermax®

Dyneon FC 2176 100 100

Maglite D 3 3

Calcium Hydroxide 6 6

SRF 20 -

Thermax® N990 - 30

Press cure 10‘@177°C+Post cure 24hrs@260°C

Tensile Strength (psi) 2120 1970

Elongation at Break (%) 220 290

Shore A Hardness 80 76

Air Ageing 70 hrs/276°C

Tensile Strength (psi) 1695 1405

Elongation at Break (%) 330 295

Shore A Hardness 81 77

Compression set (%) 50 28

- Method B (0.139” O rings) 70 hrs/200°C

FKM O-ring Compound 1 Compound 2

Thermax® enables higher loading while maintaining adequate original mechanical properties with excellent ageing properties, compression set resistance and low swell


Ethylene Propylene Diene Rubber (EPDM)


Structure

CH3|

Ethylene Propylene

CH2 = CH2 + CH = CH2 + A Diene Monomer

Diene Monomers Used in EPDM

• DCPD - dicyclopentadiene• ENB - ethylidene nobornene• VNB - vinyl norbornene

Typically, ethylene comprises 45% to 80% of the polymer with the diene making up 2.5% to 12%.


Increasing the ethylene content in EPDM provides:• Improved cold green strength• Excellent theroplasticity which improves extrusion and mold

flow characteristics• Increased filler and oil loading ability• Higher heat resistance• Good cured tensile strength properties

But:• It is responsible for less building tack• It is more difficult to mix• Mill processing at low temperatures is difficult• Compression set and recovery in cold temperatures is poor• Flex resistance and elastic recovery are reduced


EPDM – Molecular Weight Distribution

EPDM Polymer can be produced with a range of Molecular Weight Distribution (MWD).

High molecular weight distribution EPDM provides for:• Excellent hot green strength, important for shaping and

continuous vulcanization• High collapse resistance critical for hollow extruded sections• Less porosity in extrudates• Excellent physical properties• Low compression set• Improved resilience• Facilitates oil and filler extension which improves the

difficult processing characteristics common to high MWD polymers

• Higher loading of filler for lower cost compounds



Increasing the diene content of the polymer provides:

• Shorter cure times• Higher resilience• Higher modulus• Lower compression set• Cure compatibility with unsaturated rubbers


Properties of EPDM

EPDM based rubber offers:• Excellent weather and ozone resistance• Excellent high & low temperature resistance• Excellent water and chemical resistance• Excellent dielectric properties

But,• Poor resistance to oils and hydrocarbon solvents• Poor adhesion


Applications of EPDM Rubber

Automotive industry• Extruded Profiles – solid and sponge• Hoses – Radiator and Heater• Seals and grommets


Appliance Industry• Washing machine parts – gaskets, elbows and hoses

Construction Industry• Glass profiles• Flooring• Membranes• Roofing

Electrical Industry• Low and Medium voltage cabling – cable jackets

Chemical Industry• Hoses• Seals

EPDM Compound Example Using Thermax®

Keltan 512 100ZnO 5St. Acid 1Benzoic acid 1Thermaxx® N990 100Winnofil S (Coated pptd CaCO3) 35Sunpar 150 60Vaselin 10 Rotor/Roll ReleaseTMTD 2MBTS 2Sulphur 2Benzene Sulphohydrazide 3Benzene 1,3 Disulphohydrazide 3

ML 1+4@100°C 19Cure time 15’@160Specific Gravity 0.52

Higher Loading reduces costs. Low compound Mooney helps efficient blowing, gives uniform cell structure

Automotive Moulded Sponge


Metallocene EPDM Technology

• The introduction of EPDM in the world market produced by Metallocene Catalyst Technology has increased the scope for the usage of Thermal Black in these rubbers considerably

• EPDM produced by Metallocene Catalyst Technology has very high molecular weight compared to traditional EPDM Rubbers produced from solution and suspension polymerization technology

• EPMD Rubbers with Metallocene Technology are very difficult to process when compounded with furnace blacks alone. Blending Thermax in blend with the furnace black lowers the compound viscosity allowing for easy processing without a negative affect on mechanical properties



• High loadings of Thermax® can reduce the compound cost without sacrificing compression set and dynamic properties

• Thermax reduces the compound viscosity which improves processing, blowing and molding properties

• The very low grit level of Thermax maintains excellent surface finish and ensures a uniform cell structure in sponge applications.

• The excellent dispersion of Thermax results in consistent heat transfer throughout the extrusion and uniform cooling

The Thermax® Advantage in EPDM Compound Applications

Chlorosulfonated Polyethylene Rubbers (CSM)

Polyethylene, a low cost plastic, is chemically modified to a cross-linkable rubber, retaining some of the important properties of polyethylene such as chemical resistance and electrical properties

This polymer is almost exclusively produced by DuPont Performance Elastomers under the trade name Hypalon®. On May 7th, 2009, DuPont announced that it will cease production of Hypalon® and completely exit the CSM business


Structure

- (CH2-CH2)x – (CH2-CH)y – (CH2-CH)z -|

Cl|

SO2

|Cl

Properties and Grades of CSM

Properties

• Excellent resistance to weather, ozone, sunlight, oxidation, alkalies and acids

• Good resistance to oil and gasoline• Good flame resistance, abrasion resistance• It is close to polychloroprene in most properties but superior

in resistance to acids, alkalies, solvents, Ozone and oxidation with better color stability

Grades

• Depending on the Cl content, range 24% to 43%, ‘S’ content around 1%, varying Mooney

• Increasing Cl content give oil and flame resistance


Applications of CSM Rubbers


Grade Cl content (%)Mooney Viscosity ML 1=4

@ 100°CHypalon 40/40S 35 56/45

Hoses

W & C

Rolls

Hypalon 45 24 37

W & C

Low Temp. Applications

Hypalon 48/48S 43 78/62

Excellent oil resistance

low permeability to Freon

Air Conditioner Hoses

Butyl Rubber (IIR)


CH3

|

|CH3

CH3

|

Isobutylene Isoprene

+

Structure

Butyl Rubber is a copolymer of isobutylene and a small amount ofIsoprene, typically around 2%

Chlorobutyl (CIIR) and bromobutyl (BIIR) rubbers are produced in a similar manner, but with and additional halogenation stage required

Properties of Butyl Rubbers

• Presence of “bulky” isobutylene groups causes slow movement of the polymer chain which gives butyl rubber excellent impermeability to air, oxygen and water

• -CH3 groups along the chains interfere with each other, reduce the speed with which the molecules

• Low unsaturation makes Butyl more resistant to heat ageing and to attacks by acids, alkalis, oxidizing agents, ozone, water and steam, than general purpose polymers such as SBR, BR and NR

• Butyl rubber is very similar in structure to polyisobutylene and has a similar glass transition temperature (Tg) of -70°C

• Butyl has low resilience and very poor resistance to compression set, oil and hydrocarbon based solvents

• Low unsaturation slows the compound cure rate and reduces Butyl’s compatibility with the more unsaturated rubbers such as NR, SBR and BR. Even small amount mixed in with these rubbers gives a disastrous effect on compound properties


• Virtually all halogenation takes place at the isoprene portions of the IIR Chains which represent approximately 2.0 mole% of the IIR Co-Polymer

• Commercial chlorobutyls contain 1.1 to 1.3% weight of chlorine and bromobutyls contain 1.9 to 2.1% weight of Bromine

• Stearic hindrance of the double bond favors substitution rather than addition, so most of the unsaturation is retained, although it is now largely isomerised

Halobutyl Rubber


-CH2-C=CH-CH2-

CH3

| (-CH2-C-CH-CH2-)

CH3

|

|X

+ (X )-

+ (-CH2-C-CH-CH2-)

CH2

||

|X

+ (HX)X=Cl or Br

Add X2 Minus H+

Isoprene Halobutyl

Butyl versus Halobutyl Rubber

Butyl rubber Chlorobutyl Bromobutyl

Cure reactivity

Compatibility with other unsaturated rubbers

Tack

Cure adhesion with other rubbers

• Increased cure compatibility reduces the need for stringent precautions against contamination with other unsaturated rubbers

• Flexibility and resistance to dry heat are almost identical for both Chloro and Bromobutyl rubber


Permeability of Halobutyl

Typical Tire Inner Liner Compound

Permeablility rates at 65°C Air Moisture100% NR 8.3 13.3100% SBR 6.8 11.0HIIR/NR (60:40) 3.1 3.0100% HIIR 1.0 1.0

The excellent permeability of Halobutyl rubber makes it a very popular choice for tire inner liners


Applications of Butyl and Halobutyl Rubber

• Inner tubes for tires (IIR, HIIR)

• Heat resistant conveyor belts (HIIR)

• Tire Inner liners (HIIR)

• Tank linings (HIIR)

• Side Walls (HIIR)

• Dampers/bridge bearing pads (IIR/HIIR)

• Tire curing bladders (HIIR)

• Adhesives/sealants (cross-linked IIR, HIIR)

• Steam/Automotive Hoses (HIIR)

• Pharmaceutical closures (HIIR)



• High loadings of Thermax® can reduce the overall compound cost without a significant loss in compound properties

• The higher loading ability of Thermax® improves the impermeability of the compound by replacing polymer with impermeable filler

• Thermax can raise the viscosity of the compound making it easier and less expensive to process

• Improved adhesion can be achieved with Thermax® which is very important for inner liner and other rubber to rubber bonding applications.

The Thermax® Advantage in IIR & HIIR Compound Applications


Questions & Answers

may 13, 2015cancarb 1. may 13, 2015cancarb 2 thermax ® thermal carbon black thermax ® vs. furnace...

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