SILICONES- AN OVERVIEW CONTENT HISTORY BASIC FACTS SYNTHESIS PROPERTIES & APPLICATION• Lubrication• Textile

Silicones –An overview. Cont... Antifoam Paper coating

What are Silicones Organo metallic polymer of

Silicone Organo metallic? Compound of

carbon with metals

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

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 -

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

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

AMPS SYNTHESIS EQUILIBRIATION METHODS: a.Reactive di and trifunctional polymerb.Non-reactive polymer

CONDENSATION METHOD:100% Reactive polymer

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

ORGANOMODIFOED POLYSILOXANE Cont…. Example Epoxy Modified Polysiloxane Carboxy Modified Polysiloxane Glycol Modified Polysiloxane Acrylates modified Polysiloxane Amino glycols Mercapto and amide modified

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

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

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

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

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

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

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

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

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

ANTI / DEFOAMING Cont… ANTIFOAM COMPOUND

ANTI/DEFOAMING EMULSION

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

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

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

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