About Silicones in a nutshell.
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SILICONES- AN OVERVIEW CONTENT HISTORY BASIC FACTS SYNTHESIS PROPERTIES & APPLICATION• Lubrication• Textile
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Silicones –An overview. Cont... Antifoam Paper coating
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What are Silicones Organo metallic polymer of
Silicone Organo metallic? Compound of
carbon with metals
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HISTORY Silicone in nature = 25.08% in the
form of silica especially silicates and quartz
Form of Silicones: Ferro silicone and calcium silicide for
making alloys in steel industries Technical grade silicone: for aluminum
and chemical industries Hyper grade: Semiconductor
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HISTORY Cont….. Term silicone - Wohler (1857) Silane synthesis - F.S.Kipping –
Father of Silicones (1904-1941) Polymer Synthesis - Hyde 1938 Direct synthesis of silane – Rochow
Muller DMPS Emulsion - AMPS Emulsion -
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CHEMISTRY AND FACTSProperties Carbon SiliconeElectro positivity
2.5 1.8
Atomic size 0.77A 1.15A
Configuration 1s2,2s2,2p2 1s2,2s2,2p2,3s2,3p2
Bond with oxygen
Prefer Double bond
Stable Single
Bond energy C- O = 339J/mole
Si –O = 444j/mole
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SYNTHESIS OF SILICONES Chlorination: Reaction of silicone
metal with methyl chloride in the presence of copper catalyst
Fractional Distillation of silane: Hydrolysis of Silane to silanol Condensation and polymerization
reaction: Silanol to cyclic and Dimethyl polysiloxane
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AMPS SYNTHESIS EQUILIBRIATION METHODS: a.Reactive di and trifunctional polymerb.Non-reactive polymer
CONDENSATION METHOD:100% Reactive polymer
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ORGANOMODIFIED POLYSILOXANE Hydrosilylation reaction
MHPS copolymer Pt-Divinyl complex synthesis Addition reaction between allyl
derivative and MHPS copolymer in presence of Pt-Di vinely catalyst
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ORGANOMODIFOED POLYSILOXANE Cont…. Example Epoxy Modified Polysiloxane Carboxy Modified Polysiloxane Glycol Modified Polysiloxane Acrylates modified Polysiloxane Amino glycols Mercapto and amide modified
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PROPERTIES - DMPS CH3 CH3 CH3 I I ICH3-Si-O-[Si-O]n-Si-CH3 I I I CH3 CH3 CH3 Bond angle between Si-O-Si = 140, O-Si-O- = 109 Silicone atom is bounded to 2 oxygen and 2
methyl Atomic radius = 117 – Covalent bond Empty d orbital
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PROPERTIES Cont….. Properties & Application
Structural Features
Consequence Properties Applications
-CH3 Non polarityFluidityHydrophobicity
SpreadibilityReleaseWater Repellent
Paint additivesDielecticRelease application
Si-O-Si Slightly polarStrong Bond
Hydrophilic/Hydrophobic
Release,Heat transfer and defoamers
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PROPERTIES: Cont… Spreadability: Low surface tension –21 dynes/cm Hydrophobic: Methyl group Dielectric properties High compressibility and resistivity Good lubricant properties for steel and other
metals Low viscosity – temperature coefficient Excellent thermal stability Good release characteristics Inert towards living organism Low vapour and high flash point
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PROPERTIES Cont… AMPSNON-REACTIVE SILICONE: CH3 CH3 CH3 I I I X –Si-O-[Si-O]n-Si-X X = CH3 I I I CH3 RNH2 CH3 R = (CH2)3NH2
Softness with bounce and slip Impart good coluor enhancement Wet feel and good handle
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AMINO SILICONE Cont… REACTIVE SILICONE CH3 CH3 CH3 I I I X –Si-O-[Si-O]n-Si-X X = OCH3, OC2H5 I I I OH CH3 RNH2 CH3 R = (CH2)3NH2
Softness with bounce, dry and silky finish Give good colour enhancement elastomeric
properties and ease of emulsifiability
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AMINO SILICONE Cont… NONYELLOWING AMINO SILICONE CH3 CH3 CH3 I I I X –Si-O-[Si-O]n-Si-X X = CH3, C2H5 I I I R’= C6H10NH CH3 RR’ CH3 R = CH2O
Softness and hydrophilicity Non yellowing nature
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AMINO SILICONE Cont… MODIFIED HYDROPHILIC AMINO
SILICONE CH3 CH3 CH3 I I I X –Si-O-[Si-O]n-Si-X X = CH3 or C2H5 I I I R’= (CH2CH2O)n OH CH3 RNHR’ CH3 R = (CH2) or (CH2)2 Softness and wet handle Hydrophilic nature and easy of emulsification
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AMINO SILICONE Cont… APPLICATION:
1. SOFTNESS: Softness of fabric depends on following
Nature Number of and distribution of amino group
2. SUPPLENESS AND ELASTICITY: Reactivity Viscosity and amine value
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ANTIFOAMING & DEFOAMING FOAM: Stable dispersion of gas in liquid
stabilised by presence of impurities or solid
DEFOAMING: Process of destroying foam that has already been formed
ANTIFOAMING: Process of preventing the formation of foam
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ANTI / DEFOAMING Cont… ANTIFOAM COMPOUND
ANTI/DEFOAMING EMULSION
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PAPER COATINGWHERE SILICONE RELEASE PAPER USED:
Backing paper for self-adhesive Silicone release paper and film in food industry Silicone release paper in production of laminates Backing paper for production of PVC and poly
urethane coated fabric Coating of underside of self-adhesive tape made
from paper or plastics film Silicone release paper and film for self-adhesive
carpet and fabric
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PAPER COATING Cont…SOLVENTLESS PAPER COATING:
ADVANTAGE: Health safety and controlled process Contain no carrier Energy cost are reduced because there is no need
to evaporate solvent or expensive ventilation Less likely to damage film No unpleasant smell
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PAPER COATING Cont…SOLVENT BASED:
ADVANTAGE: Good coverage at very low cost weight Economical Use conventional coating equipment such as
Meyer rods and direct gravures Slight swells some film surfaces, improving
anchorage
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PAPER COATING Cont…SOLVENTLESS PAPER COATING:
DISADVANTAGE: Required health and regulatory safety control
than solvent free Paper coating damage High energy cost Greater potential for silicone migration