40. Silicone Rubbers- Properties and applications- Hans mueller.ppt

CREATING TOMORROW'S SOLUTIONS

Johann Müller, Wacker Chemie AG, January 2011

SILICONE RUBBER – PROPERTIES AND APPLICATIONS

Silicone Rubber – Properties and ApplicationsJohann Müller, Wacker- Chemie AG, January 2011

AGENDA

• Raw materials for silicone rubber

• Production of silicone rubber

• Liquid and solid silicone rubber• processing• crosslinking

• Properties of silicone rubber

• Silicone rubber in comparison to other elastomers


AGENDA







NATURAL RAW MATERIALS: SALT AND SAND

• Salt:

• Natural NaCl production of chlorine via chloro-alkali-electrolysis

• Sand:

• Quartz is mainly Silicondioxide SiO2; production of silicon via reduction process


RAW SILICON

• Does not occur as pure element in nature

• Has to be gained from quartz (SiO2) in an highly energy consuming process

• Silicone of high purity (>99%) is needed

SiO2 + C Si + CO2


CHLORINE

• Does not occur as pure element in nature

• Has to be gained from salt (NaCl) in a highly energy consuming process (electricity)

• Corrosive gas

2 NaCl + 2 H2O 2 NaOH + H2 + Cl2


CHLORINE, SILICONE AND ORGANICS: SILANES

• Reaction of organic chlorides with silicone metal in the Müller-Rochow-Process

Cl2

MeCl

Si

SiCl4

MeSiCl3

Me2SiCl2

Me3SiCl

Me4Si

Cu-cat.

Methanol

+ HCl - H2O


DISTILLATION OF SILANES

yield approx. 98% Me2SiCl2 in >99,9% purity


AGENDA







MAIN COMPONENT 1: POLYMERS

H2O

Me2SiCl2

Me3SiCl

Si

Cl

ClMe

MeSi

HO

OHMe

Me- HCl - H2O Si

O

OMe

Me

Me

Si

Me

Si

Me

MeHO

- HClSi

Me

MeMe

• Silicon-Oxygen-Polymer: Polysiloxane (Q)

instead of Me (Methyl)

also Ph (Phenyl)

or Vi (Vinyl)


CHEMICAL STRUCTURE OF POLYMER CHAIN

MQ (Methylpolysiloxane) side groups = Methyl

VMQ (Methyl-vinyl-polysiloxane) side groups = Methyl or Vinyl

PVMQ (Methyl-phenyl-vinyl-polysiloxane)side groups = Methyl or Vinyl or Phenyl

FVMQ („Fluorosilicone“)side groups = Methyl or Vinyl or fluorinated organic groups

Si Si SiO O O

Si Si SiO O O

Si Si SiO O O

Si Si SiO O O


MAIN COMPONENT 2: SILICA

• skeleton based on oxygen and silicon, similar to quartz

• two main production processes:

SiCl4

water

thermolysis

precipitated silica

fumed silica (HDK®)


FUMED SILICA:HOCHDISPERSE KIESELSÄURE (HDK®)

SiCl4 + 2 H2 + O2 SiO2 + 4 HCl

burnerSiCl4 +

2 H2 + O2

proto-particles

SiO2

SiO2SiO2

SiO2

SiO2

SiO2-molecules agglomerates

primary particles

aggregates


MIXING OF SILICONE RUBBER

Base Polymer

Custom Compound(Roll Mill)

Active Filler(HDK)

CrosslinkingSystem

Additives

Kneader


PRODUCTION SCHEME

Silanes

quartz sand

Silicon

HDK®

fumed silica

silicone rubber

crosslinkeradditives

Si-Wafer

Siloxanes

oils silicon polymers

silicon


AGENDA







CLASSIFICATION OF SILICONE RUBBER BY CURING TEMPERATURE AND VISCOSITY

silicon rubber

high temperature

curing silicone rubber HTV

room temperature curing RTV

solid silicone rubberHCR

solid silicone rubberHCR

liquid silicone rubberLSR

peroxide cureperoxide cure addition curePt-catalyzed

addition curePt-catalyzed


two componentRTV-2

one component

RTV-1


condensation cure

Sn-catalyzed

condensation cure

Sn-catalyzed


LIQUID SILICONE RUBBER:PROCESSING

(1) pumps(2) color

dosage(3) static

mixer(4) dosing

unit(5) mould


LIQUID SILICONE RUBBER: COMPONENTS

• Polymer + filler

• Pt-catalyst

B-ComponentA-Component


• Crosslinker

• Inhibitor


• Crosslinker

• Catalyst

• Inhibitor


LIQUID SILICONE RUBBER:KINETICS OF PT-CATALYZED CROSSLINKING REACTION

torque

time

Pt-catalyzed reaction

Peroxid

170 °C


ELASTOSIL® LR: PREPARED FOR VARIOUS APPLICATION AREAS

media resistant

flame retardant

standard

self lubricating

non post cure

fast curing

tear resistant

self adhesive

heat resistant

electrically conductive

highly transparent


LIQUID SILICONE RUBBER:SUMMARY

• 2 component system:

• Crosslinking via hydrosilylation of vinyl groups of the VMQ-polymer

• Curing temperatures above 100 °C

• No vulcanization at 25 °C (room temperature - pot life)

• Catalyst: platinum compound

• Reactants are:

VMQ-polymers with terminal vinyl groups (polymer)

VMQ-polymers with at least 3 Si-H-groups (crosslinker)

Pt-catalyst


SOLID SILICONE RUBBER (HCR)DELIVERY FORMS


SOLID SILICONE RUBBER:PROCESSING

• Mixing of additives or mixing of 2-K products on the open mill:

Important requirements:• Mills have to be cooled (not too cold in order to avoid

condensation of H2O on the surface)• Pt-catalyzed compounds have to be stored under cooled

conditions (< 25 °C)• Surface of mill has to be polished

• Crosslinking is done depending on production process:• Extrusion: crosslinking via salt bath, steam, hot air or IR-

channel (pressureless) • Press vulcanization: crosslinking in presses with heating

(under pressure)• Injection molding


SOLID SILICONE RUBBER: Pt-CURING GRADES ELASTOSIL® R plus


• Crosslinker

• Inhibitor

CatalystELASTOSIL® R plus

- Pt1 respectively Pt2


• Crosslinker

• Catalyst

• Inhibitor

2 K

1 K


SOLID SILICONE RUBBER:Pt-CATALYZED GRADES ELASTOSIL® R plus

• Curing catalysed via platinum compounds

• 2K-grades and 1K-grades

• Processed at 150-170 °C by injection mouldingcompression molding or

extrusion

• Highest mechanical strength within the silicone elastomer family


SOLID SILICONE RUBBER:PEROXIDE CROSSLINKING

C O O C

CH3

CH3

CH3

CH3

C O O C

O O

Cl

Cl

Cl

Cl

C CH2 C

CH3

CH3

CH3

CH3

CH2C O O

CH3

CH3

H3C O O C

CH3

CH3

CH3

crosslinking temperature

170 - 190 °C

> 100 °C

165 - 190 °C

Extrusion:

Molding:


LIQUID SILICONE RUBBER:KINETICS OF PT-CATALYZED CROSSLINKING REACTION

torque

time

platinum cure

Peroxid

170 °C


SOLID SILICONE RUBBER:KINETICS OF CROSSLINKING

torque

time

platinum cure

peroxide cure

170 °C


SOLID SILICONE RUBBER:PEROXIDE CURING GRADES ELASTOSIL® R

• Curing through organic radicals by peroxide (E, C1, C6) decomposition

• Processed at 160-190 °C by compression molding orinjection moulding or

extrusion

• Very high mechanical strength


POSTCURING OF SILICONE RUBBER ARTICLES

• Recommendations for thermal post-treatment of vulcanisates

• Use of enough fresh air: 120 l per kg and min

• Duration: 4 hours at 200°C (> 4 mm: + 2h/mm)

• Loose packing of articles

• Do not mix peroxide and Pt-cured articles

• Reasons for postcuring:

• Minimization of peroxide decomposition products (not in case of Pt-cure)

• Decomposition of excess crosslinker components

• Optimization of physical properties

• Minimization of volatiles


SOLID OR LIQUID SILICONE RUBBER?

Advantage:

• Short cycle time (low viscosity, high vulcanization speed)

• Fully automized process

• Molds with up to 128 cavities

• Possibility of producing articles with complex geometry

• 2-component-injection molding

• No reworking (no flash etc.)

solid siliconeliquid silicone

Advantage:

• Better physical properties of products

• Higher flexibility in processing • Molding• Extrusion• Calendaring• Assembly


PEROXIDE OR Pt-CATALYZED CROSSLINKING?

Advantage:

• Fast crosslinking

• No by-products from crosslinker

(BfR, FDA, KTW, medical)

• High transparency

• Dry surface

• Better physical properties (tear resistance, elasticity, etc.)

peroxide curePt-(addition-)cure

Advantage:

• Not sensible towards catalyst poisons

• „Unlimited“ storage time for compounds


AGENDA







PROPERTIES OF SILICONE RUBBER


CH3

Si O

CH2CH

mnCH3

Si O

CH3

PROPERTIES OF SILICONE RUBBER DERIVATION FROM STRUCTURE OF POLYMER

• Inorganic, fully saturated backbone

• High bonding energy: Si-O 451 kJ/mol (for comparison C-C 352 kJ/mol)

• Low surface energy, organic side groups shield backbone

• High flexibility of chains

Excellent high temperature resistance and low temperature flexibility

High resistance towards chemicals and environmental influences

Water and dirt repellant surface

Silicone Rubber – A General IntroductionDr. Jürgen Ismeier, Wacker Chemie AG, Wacker Academy 29.11.2010, Slide 49


CH3

Si O

CH2CH

mnCH3

Si O

CH3 SiO2SiO2

SiO2

PROPERTIES OF SILICONE RUBBER DERIVATION FROM STRUCTURE OF POLYMER AND FILLER

• High similarity of structure of polymer and filler

• Polymer and filler contain only Si, O, C and H

High transparency

Good mechanics due to effective polymer-filler-interaction

Good flame retardant properties, in case of combustion only non-toxic combustion products


TYPICAL MECHANICAL PROPERTIES OF SILICONE RUBBER

Specific gravity 1.05-1.35 g/cm³

Hardness 3-90 Shore A

Tensile strength at break 5-11 N/mm²

Elongation at break 100-900 %

Tear resistance (ASTM D 624) 5-50 N/mm

Compression set (175°C, 22 h) 10-25 %

Rebound resilience 20-70 %


PROPERTIES OF SILICONE RUBBER

• Broad range of usage temperature from -50 °C up to +250 °C (special grades -110 °C up to +300 °C)

• Almost no change of properties between 0 °C and 150 °C

• Electrically isolating to semi-conductive

• Resistant to radiation, ageing and weathering

• Transparent, easily pigmentable

• Excellent compression set

• Neutral taste and smell (a lot of grades comply with regulations of BfR and FDA)

• Easy processing


AGENDA







SILICON RUBBER IN THE WORLD OF ELASTOMERS


RUBBER CLASSIFICATION

price

volume

High Performance

Elastomers

• FKM

• HNBR

• MVQ, PMVQ, FMVQ

• (E)CO

• EVM, AEM, ACM

• CSM

General Purpose Elastomers:

NR, BR, SBR

Speciality Elastomers:CR, NBR, EP(D)M,

(X)IIR

82 % volume 60 % turnover

17 % volume 30 % turnover

1 % vol. 10 % turnov.


HEAT- AND OIL-RESISTANCE(ACCORDING TO ASTM-D 2000/SAE J 200)

maximum swelling in oil IRM 903 (%)

heat

res

ista

nce*

(°C

)

50

100

150

200

250

10 20 140

EPDM

MVQ

FPM

NBR

ACMHNBR

BRNR

SBR

30 40 60 80 100 120

40% VA80% VA

34% ACN

18% ACN

44% ACN

48% ACN

no requirements

NR

SBR

BR

IIRNBR

CR

EPDM

VMQ

EVM

FKM

HNBR

CM/CSM

ACM AEM

CO/ECO

HT-ACM

FVMQ

* temperature at which after 1000 hours, 50 % of initial elongation at break are retained


LOW TEMPERATURE FLEXIBILITY AND HEAT RESISTANCElo

w t

empe

ratu

re f

lexi

bilit

yT

R (

°C)

acco

rdin

g to

DIN

535

20

FVMQ

0

60 80 100 120 140 160 180 200

-20

-40

-60

-80BR

SBR

CR

HNBR

ACM

ECO

NR

SBR

BR

IIR

NBRCR

EPDM

CO/ECO

VMQ

CM/CSM

ACM

AEMEVM

FKM

HNBR

220 240 260

* temperature at which after 1000 hours, 50 % of initial elongation at break are retained heat resistance* (°C)


SUMMARY OF PHYSICAL PROPERTIES

NR BR SBR EPDM IIR CR NBR CSM/CM ACM EVM AEM ECO/CO VMQ HNBR FKM FVMQ

heat resistance

low temperature flexibility

oil resistance

fuel resistance

ozone-/weathering resistance

mechanical properties (23 °C)

mechanical properties (100 °C)

tear resistance

abrasion resistance

low temperature C.S. (-20 °C)

high temperature C.S. (120 °C)

gas impermeability

processing

prics

Rating (all properties except price) price

high

low

medium

excellent

fair

weak


SILICONE RUBBER APPLICATIONS

20%

20%

10%

15%

25%

10%

Silicone Elastomer

Market 20091.8 BN EUR*

* Source: WACKER estimates

Sports and FashionOthers

Automotive

Electrical EnergyT&D, Cable

Electronics Photonics

HouseholdMachinerySanitary

Medical and Health Care

Solar

Baby Care

25%

15%20%

10%

10%20%


THANK YOU

FOR YOUR ATTENTION!

Documents

40. Silicone Rubbers- Properties and applications- Hans mueller.ppt