Room Temperature Vulcanizing RTV Silicones
CREATING TOMORROW’S SOLUTIONSROOM TEMPERATURE VULCANIZING(RTV) SILICONESMaterial and Processing Guidelines
2
WELCOME TO THEWORLD OFRTV SILICONESContentsSection 1: Discover DiversityWhy WACKER silicones optimize the properties andprocess technologies of products in all major industries worldwide.5Section 2: Silicone Rubber – Basic PrinciplesBenefit from the chemical structure, components, classes andproperty profile of our silicone rubber in your application.13Section 3: Understanding RTV SiliconesShort cycle times for mass production or ease of processingwith minimal investment – RTV silicones score with advantageousproperties.21Section 4: Preparing for ProductionWell begun is half done: From safety, systematic selectionand working with RTV silicones to physical and chemical surfacepreparation methods.31Section 5: Processing RTV SiliconesHow to process, modify and store silicones to achieve bestresults for industrial scale production.41Section 6: Spectrum of Technical ApplicationsSealant adhesives, silicone gaskets, potting, encapsulation,coating and casting.57Section 7: ServiceExcellent technologies need best-in-class services.WACKER ACADEMY, technical centers and e-businessoffer excellent expertise and support.71Section 8: Silicones A – ZFacts and figures on RTV silicone rubber.77ELASTOSIL , LUMISIL , SEMICOSIL ,WACKER SilGel and SILPURAN are registeredtrademarks of Wacker Chemie AG.3
4
Discover DiversitySECTION 1:DISCOVER DIVERSITYContentsWhy WACKER silicones optimize the properties andprocess technologies of products in all major industries worldwide.1.1 Diversity in Silicones61.2 Relevant Industries81.3 General Properties of RTV Silicone Elastomers105
1.1DIVERSITY OF SILICONESTechnical innovations and rapidproduction development cycles areroutine in specialized industries.However, to achieve market leadership in the long-term, it is necessaryto set standards. Modern siliconebased materials increasingly playa key role in achieving such goals.6Room-temperature-vulcanizing (RTV)silicone rubber compounds are a traditional core competence of WACKER.The range of ready-to-use productsfocuses on numerous applications inthe fields of bonding, sealing, potting,encapsulation, coating and casting.Equally broad is WACKER’s experience in processing techniques andmaterial requirements specific to theseapplications, from DIY-scale right up toindustrial production lines.With more than 60 years' experiencein silicone technology and anabove-average commitment to R&D,WACKER has long become indispensable to its customers and participatesin their technical progress. This wouldnot be possible without ongoing,confidential dialog and the exchangeof knowledge, experience and ideas,which powers a shared undertaking.
7Discover Diversity
1.2RELEVANT INDUSTRIESE-Mobility– Battery– Fuel cell– Electric motor– Cables and dustry– Steam irons– Dishwashers– Drive train– Ovens– Seals and gaskets– Kitchen hoods– Dampers– HobsMining andExploitationHealth Care– Automotive electronics– Consumer electronics– Power modulesElectronics8Aerospace
Discover DiversityEnergy Sector– Solar industry– Wind power– Hydro power– Oil & gasFood IndustryLightingFire SafetyApplications– LED– Secondary optics– Cable and pipe duct seals– Luminaires– Seat cushions– Orthopedics and prosthetics– Gluing and fixing of silicones– Wound care– O-rings, profiles– Dental careMedicalApplications– Construction moldingRubber Industry– Industrial printing– Prototype molding– Composite industry– Reproduction molding– Utility vehiclesMolding andMold Making– Marine industry– Railway systemsTransportation9
1.3GENERAL PROPERTIES OFRTV SILICONE ELASTOMERSConstantproperties overa wide range oftemperatures andfrequenciesExcellent thermalresistanceOutstanding longterm thermalstability from-50 C to 180 COutstandingdielectricpropertiesVery goodadhesion to avariety ofsubstratesHigh chemicalpurity andbiocompatibilityWACKERRT V SILICONEEL ASTOMERSExcellent releaseproperties10Superiorweathering,UV and radiationresistance
Discover DiversitySelective entsurface and lowmoisture uptakeLow Young’smodulusVery ility andno harmfuleffectsFlame resistance11
12
Silicone Rubber –Basic PrinciplesSECTION 2:SILICONE RUBBER –BASIC PRINCIPLESContentsBenefit from the chemical structure, components, classes andproperty profile of our silicone rubber in your application.2.1 Chemical Structure142.2 Components of Silicone Rubber152.3 Classes of Silicone Rubber162.4 Properties of Silicone Rubber182.5 Properties of RTV Silicone Elastomers1913
2.1CHEMICAL STRUCTURESection of a Polydimethylsiloxane 3From Quartz to SiliconeSilicones are made from quartz. Whilethis raw material is available in practically unlimited quantities, the qualityis crucial. WACKER converts quartzinto silicon metal (Si) via a metallurgicalprocess. Then silicon metal is transformed into silanes by an integratedproduction system based on theMüller-Rochow process. These silanesare the precursors of polysiloxanes.Polysiloxanes are macromolecules(polymers) comprised of a siliconoxygen backbone with an organicmoiety bound to the silicon atom.They are the basis for around 3,000different silicone products.14The properties of silicone rubbervary greatly depending on the organicgroups and the chemical structure.The organic groups may be methyl,vinyl, phenyl or other groups. According to DIN EN ISO 1043-1, siliconesare classified as follows:MQ: MQ, or polydimethylsiloxane(PDMS), denotes a polymer in whichtwo methyl groups are bound to thesiloxane backbone.VMQ: VMQ stands for a polydimethylsiloxane in which a number of methylgroups have been replaced by vinylgroups.PVMQ: PVMQ stands for a VMQin which a number of methylgroups have been replaced byphenyl groups.FVMQ: FVMQ stands for a VMQ inwhich a number of methyl groups havebeen replaced by fluorinated organicsubstituents.
Silicone Rubber –Basic Principles2.2COMPONENTS OF SILICONE RUBBERUncured, Filled Polymer Compared with Cured RubberCuringUncured polymer with filler.Besides polysiloxanes of differentchain lengths, uncured siliconerubber generally contains only afew additional substances, suchas crosslinkers, fillers, additivesand colorants.CrosslinkersA crosslinker is required to convertthe uncured rubber into a mechanicallystable cured product. Dependingon the class of the silicone rubber,peroxides, silanes or SiH-containingpolysiloxanes are required forcrosslinking, also called curing orvulcanization.Polymer with chemicalcrosslinks (red) forms a filled,elastic network.FillersFillers are needed to reinforce theelastic silicone network. The nature,composition and quantity of the fillershave a crucial influence on the properties of the uncured and cured rubber.Reinforcing fillersThe most frequently used reinforcingfiller is pyrogenic silica with very highBET surface areas (higher than100 m²/g). WACKER HDK hasproven to be especially effective,although precipitated silica, siliconeresins or carbon black can also beused.Non-reinforcing fillersThese function merely as a fill-up.Quartz, finely powdered calciumcarbonate, talcum or diatomaceousearths, for example, increase the curedrubber's resistance to various media.AdditivesCompared with other elastomers,silicone rubber requires few additivesbecause the essential properties aredetermined by the polysiloxane itself.Thus, a silicone rubber compoundmay comprise only polymer, crosslinker and filler.The choice of additives determinesthe material properties and theprocessing at the customer. Additivescan be catalysts, heat stabilizers,adhesion promoters, rheology modifiers and colorants, for instance.The fact that some of these additivesare naturally colored should be takeninto account by the customer asthis may have an impact on the finalcolor of the compound.ColorantsSilicone rubber is generally transparentto opaque but can be coloredaccording to customers’ requirements.For this purpose, WACKER offers abroad range of pigment pastes thatcan easily be blended with RTVsilicone rubber compounds.15
2.3CLASSES OF SILICONE RUBBERUncured silicone rubber is convertedinto elastomer by vulcanization.Depending on the curing method,the viscosity of the base polymer andthe curing temperature, silicones areclassified as follows: 1-part room-temperature vulcanizingsilicone rubber (RTV-1) 2-part room-temperature vulcanizingsilicone rubber (RTV-2) Liquid silicone rubber (LSR) High-temperature vulcanizing siliconerubber (HTV).1-Part Room-TemperatureVulcanizing Silicone Rubber (RTV-1)RTV-1 silicone rubber formulationsare one-part, ready-to-use systems.They consist of polysiloxane, curingagent, fillers and additives. Rightafter application, the material startscrosslinking on contact with moisturein the air. Byproducts are releasedduring curing. Crosslinking starts withthe formation of a skin on the rubbersurface and gradually progressesinto the compound. Depending onthe nature of the crosslinker, a smallamount of acetic acid, amine orneutral byproducts, such as alcohol,is released during vulcanization.RTV-1 silicones are ideal for almostall sealing, bonding and coatingapplications. They are used in theautomotive, construction, electricalengineering, electronics, health care,medical and textile sectors, amongothers, and also for householdappliances.16
Special RTV-2 silicone rubber gradescan be flash vulcanized using UVlight. The vulcanization time can becontrolled by adjusting the UV intensityand exposure time.For process reasons, additioncuring RTV-2 silicone rubber canbe formulated as premixed onecomponent systems that contain aslow-acting catalyst and only vulcanizeat elevated temperatures. Thesesystems are characterized by a longshelf life (up to 12 months) whenstored at room temperature (20 C to25 C). This group is known as onecomponent heat-curing silicones andis classified as RTV-2.Most RTV-2 silicone elastomers –silicone rubber in a cured stage –retain their full elasticity at up to180 C, even after long-term exposure.Some products even withstand shortheat exposure up to 300 C. At lowtemperature, they retain their flexibilitydown to -50 C. Some special gradesremain flexible even down to -110 C.The extensive portfolio of RTV-2silicone rubber products enables theproduction of silicone elastomerswith extremely versatile and highlyspecialized properties.Like RTV-1 silicones, RTV-2formulations are ideal for almostall sealing, bonding and coatingapplications. They are used for moldmaking, household appliances andhealth-care applications as well asin a number of industries such asmechanical engineering, industrialprocess engineering, lighting technology electronics, optoelectronicsand solar/photovoltaics.WACKER silicone gels and siliconefoams are special types of additioncuring RTV-2 silicones. Silicone gelsare characterized by a particularlylow crosslinking density and producevery soft vulcanisates below the Shorehardness range. They are suitable forvarious applications in industries suchas: automotive, transmission anddistribution, as well as health careor wound care. Specific gels suchas low-temperature flexible gels andfluorinated materials were developedespecially for the automotive industry.They exert only minimal stress onencapsulated components exposedto temperature fluctuations.Silicone foam formulations arecharacterized by a high crosslinkercontent, namely, an SiH-richpolysiloxane. Its basic function is tocrosslink the liquid formulation andrelease hydrogen, which acts as ablowing agent as curing progresses.Silicone elastomer foams are typicallyused in applications such as lightweight construction, damping,insulation and fire safety.Liquid Silicone Rubber (LSR)Liquid silicone rubbers are hightemperature-vulcanizing silicones.Their consistency and addition-curingmechanism provide them with uniqueprocessing advantages. Liquidsilicone rubber has a lower viscositythan solid silicone rubber (HTV). Itis thus pumpable and delivered asa two-component and ready-to-usesystem. LSR is an addition-curingsilicone, where the curing catalyst incomponent A is a platinum compoundand in component B, the curing agentis an SiH-functional polysiloxane. Nobyproducts are released during theLSR curing process.Like all silicones, LSR is also used ina wide range of industries: automotive,mechanical and process engineering,electrical engineering, transmissionand distribution, construction, food,health care, baby care and the medicalsector. WACKER offers specificautomotive applications, like fluorinated LSR, which is highly stable oncontact with media such as gasoline,engine and gear oils.High-Temperature VulcanizingSilicone Rubber (HTV)HTV silicone rubber contains longpolymer chains with a high molecularweight, which provides the rubber witha solid consistency. For this reason,HTV silicone rubber is also called solidsilicone rubber or High Consistencysilicone Rubber (HCR). HTV siliconerubber cures by means of organicperoxides or a platinum catalyst atan elevated temperature.Thanks to their outstanding mechanicalproperties, HTV silicone elastomers areused in a large variety of applicationsin the automotive, electrical engineering, transmission and distribution,construction, mechanical and processengineering, food, health-care andmedical industries.Solid silicone rubber bar (standard supply form).17Silicone Rubber –Basic Principles2-Part Room-TemperatureVulcanizing Silicone Rubber (RTV-2)RTV-2 silicone rubber formulationsare two-part pourable, spreadableor kneadable compositions thatvulcanize after mixing. They usuallycure at room temperature (RTV room-temperature vulcanizing) andform a highly elastic material. Thereare two different types of crosslinkingreactions, either by condensation or byaddition. Condensation curing requiresan organotin catalyst and alwaysreleases byproducts. Addition curingrequires a platinum catalyst and doesnot generate any byproduct.
2.4PROPERTIES OF SILICONE RUBBERMaterial Benefits Resulting fromthe Polymer StructureSilicones are characterized by a fullysaturated backbone of alternatingsilicon and oxygen atoms. The Si-Olinks in the chain have an exceptionallyhigh bond energy of 451 kJ/mol.By comparison, C-C links have a bondenergy of 352 kJ/mol. At the sametime, the Si-O chain mobility is veryhigh. The organic side groups shieldthe backbone, so that the surfaceenergy is low.This results in the following properties: Excellent high-temperatureresistance combined withlow-temperature flexibility High resistance to chemicalsand environmental influences Excellent weathering,UV and radiation resistance Water-repellent surface.18Low-Temperature Flexibility versus High-Temperature ResistanceLow-temperature flexibility [ C]Inherent PropertiesSilicone elastomers are generallyexpected to be heat resistantand flexible at both high and lowtemperatures. In contrast to organicrubbers, this doesn't come at theexpense of the other properties.Silicone elastomers keep theirexcellent mechanical propertiesover a very wide temperature range.These characteristics, intrinsic tosilicone elastomers, are attributableto the polymer and filler structure,not additives or surface HNBREPDMNR-60IIRBRSiliconesUsing heat rature resistance* [ C]* Temperature at which – after 1000 h – half of the initial elongation at break remainsMaterial Benefits Resulting fromthe Filler StructureSilicone rubber usually containspyrogenic silica as a filler, e.g., HDK from WACKER. Since pyrogenicsilica and polysiloxanes are verysimilar in structure, high compatibilityis a given, resulting in the followingcharacteristics: High transparency Good mechanical properties thanksto effective polymer-filler interaction Flame resistance and non-toxic combustion products in the case of fire.High PurityCompared to many organicelastomers, silicones are consideredexceptionally pure. Thanks to theirbiocompatibility and physiologicalinertness, silicone elastomers arehighly suitable for applications inthe food, medical and electronicsectors. For this purpose, WACKERhas developed the SILPURAN brand and specific products withinthe ELASTOSIL and SEMICOSIL ranges. Some of these productsfeature an exceptionally low ionic orvolatile compound content.
Silicone Rubber –Basic Principles2.5PROPERTIES OFRTV SILICONE ELASTOMERSGeneral Properties ofRTV Silicone Rubber Outstanding long-term thermalresistance from -50 C to 180 C;Specialty grades: down to -110 Cor up to 270 C (peak temperatureload may be even lower or higher) Only slight changes in physicalproperties between -50 C and 180 C Low elasticity modulus Coefficient of linear thermalexpansion approx.150 10-6 – 300 10-6 m/(m K) Outstanding dielectric properties Constant properties over a widetemperature and frequency range Electrically insulating High weathering,UV and radiation resistance Fire retardant Very good chemical resistance Easy to process Water-repellent surface pairedwith low moisture uptake Odorless and tasteless (manygrades are BfR and FDA compliant) High chemical purity Chemical inertness andbiocompatibility High gas permeabilityTypical Range of MechanicalProperties Density: from 0.97 up to over3 g/cm³ Hardness: 20 Shore 00 - 80 ShoreA, or jellylike Tensile strength: 2 - 10 N/mm² Elongation at break: 100 - 900 % Tear strength (ASTM D 624):5 - 30 N/mm Compression set(22 h /175 C) 5 %Main Property Options (Self-)Bonding or non-adhesive Thermally insulating or thermallyconductive Electrically insulating or electricallyconductive Wide range of viscosity and hardness Pigmentable19
20
UnderstandingRTV SiliconesSECTION 3:UNDERSTANDINGRTV SILICONESContentsShort cycle times for mass production or ease ofprocessing with minimal investment – RTV silicones scorewith advantageous properties.3.1 RTV-1 Silicone Rubber223.2 RTV-2 Silicone RubberCondensation-curing RTV-2 siliconesAddition-curing RTV-2 silicones– Two-component silicones– One-component heat-curing silicones– UV-curing silicones24242621
3.1RTV-1 SILICONE RUBBERCondensation Curing (RTV-1)RX Si XOH XStep 1XR Si XXOHXX Si ROHXOHStep 2HOXSi XHOX RXX Si R H OOHXHORX Si XOXRSiOXX Si OXO SiRXXRO SiOXX SiR XR XXO SiRXELASTOSIL A:NR2WACKER's RTV-1 silicone rubbercompounds are one-componentsytems that cure at room temperature.Thanks to their ease of processing,ELASTOSIL RTV-1 silicones arepreferred for applications involvingthin layers and tolerable curing times.However, these grades require longcuring times if applied in thick layers.This is not compatible with the shortcycle times required in mass production. In such cases, fast-curing RTV-2systems, one-component heatcuring silicones, or UV-curing gradesare more advantageous. In all othercases, RTV-1 is appropriate.ELASTOSIL RTV-1 silicones owetheir popularity to their advantageousproperties in combination withminimal investment.22XRO SiXX Si OCatalyst– volatile by-product (HX)XO SiRXXRO SiOXX SiR XR XXO SiRXXO Si RXRCatalyst, moistureRR– volatile by-product (HX)XO Si RXRRELASTOSIL E:R1X RX Si XOXX Si RXH OO HHOOHX ORELASTOSIL N:R1CH 3OBenefits at a Glance Very easy handling and processing Low capital investment for processingequipment Very good adhesion to a large varietyof substrates Insensitive to inhibition by othersubstances Available as flowable, self-levellingor non-sag gradesX OR1orNOR2Curing ChemistryELASTOSIL RTV-1 silicone rubbercompounds consist of polysiloxanes,curing agents, fillers and, in somecases, solvents and/or additives. RTV-1silicones require air moisture to cure.Since a small amount of by-productsis released during crosslinking,RTV-1 silicones are classified as
rubber's resistance to various media. Additives Compared with other elastomers, silicone rubber requires few additives because the essential properties are determined by the polysiloxane itself. Thus, a silicone rubber compound may comprise only polymer, cross-linker and filler. The choic
ATV HDWS TURF Front guard design 25 12-12, 4-ply (N/A RTV-X1100C Camo) - Alloy wheel Simple, center only Center and bumper Centre, bumper and lens Centre and bumper . adjustment of the front and rear suspension height will ensure the proper vehicle height for a smooth ride and optimum driveability for hard to get to work environments. COMFORT
400mg daily w/food With TDF, H2RA or PPI: ATV RTV 300/100mg daily w/food With EFV: ATV RTV: 400/100mg daily w/food Pediatric 6yr: 15-24kg; ATV RTV 150/80mg daily; 25-31kg: 200/100mg daily; 32-38kg 250/100mg daily; 39kg 300/100mg daily w/food 13yr, 39kg and unable to tolerate RTV: ATV 400mg daily w/food Experienced Adult
insulation strength, heat stability, resistance to shock, vibration and moisture. These were met conveniently and easily by mounting the components on a printed circuit board, encapsulating the unit with Silastic RTV, the Dow Corning room-temperature vulcanizing silicone rubber. Silastic RTV is poured over the unit until the mold is com-
of innovative and reliable products under the Dow Corning label for more than seven decades. Today that legacy continues under . Part of Dow's portfolio of room-temperature cure (RTV) silicone adhesives, DOWSIL SE 9160 Adhesive offers the option . DOWSIL 3145 RTV Mil-A-46146 Adhesive/Sealant DOWSIL 3165 Fast Tack RTV Adhesive Sealant
contractors. Our expertise in formulating ultra-high purity silicones and fabricating silicone components allows us to develop innovative technologies that serve vital and demanding requirements. SILICONES FOR AVIATION AND DEFENSE. From interior applications like digital avionics displays to exterior aircraft coatings and silicone gaskets, our
Frame formulation Number: 1.2 - 2013 SKIN CARE CREAM, LOTION, GEL - WITH HIGH LEVEL OF SILICONES Ingredients Maximum levels (% w/w) Silicones including volatile silicones (e.g. cyclopentasiloxane, dimethicone) 50 Oils (e.g. vegetable and/or mineral), waxes and fats (e.g. lon
The fundamental building block of a silicone sealant is polymeric siloxane. This is often represented by Silanol end-capped Polydimethylsiloxane. The silanol (-OH) terminated silicone polymer is the basis for the formulation of one component, moisture curing RTV silicone sealants, and two-component, condensation curing RTV silicone compounds.
Conduct an API-653 inspection of your tank every five years as recommended by TFI (The Fertilizer Institute) WHAT IS THE API 650 SPECIFICATION API - AMERICAN PETROLEUM INSTITUTE Worldwide Standard for Above Ground Storage Tank Design and Construction Provides requirements for calculations of shell plate thickness, man-way and nozzle design Provides procedures for shell, roof and floor .
