SILICONE RUBBERS
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General Characteristics of silicone rubbers
Technical Data Sheet
Chemical Resistance Chart
Tolerances
General Characteristics of silicone rubbers
(VMQ Vinyl MethylSiloxane)
Renowned chemist Frederick Kipping was a pioneer in the study of organic compounds with carbon and silicon molecules and was responsible for the name 'silicone'. Silicone is a combination of quartz rock and carbon at high temperatures, obtaining a silicon-based rubber. From this basic substance other physical states such as gels, oils and solids are formed.
Silicone has a high transparency, is versatile and has an excellent behaviour in different physical and chemical working conditions. It can be transformed by injection, compression moulding, extrusion, autoclave, casting, etc.
Thermal Resistance: Silicone rubberus have an excellent behaviour and stability at temperatures from -55 ºC up to +225 ºC and our THT silicones can work up to +320 ºC in dry heat. There are silicones which can reach working temperatures of -90 ºC, such as the Phenyl-Vinyl-Methyl-Siloxanes (PVMQ). We have special vapour resistant (wet heat) silicones which are stable up to +150 ºC constant temperature.
Non toxicity standards:Inert material which can comply the following international standards for medical, pharmaceutical and foodstuff contact:: FDA CFR 177.2600 (US Food and DrugAdministration), BgVVBfR cap.15 (Bundesinstitut für Gesundheitlichen Verbraucherschutz Und Veterinärmedizin), USP Clase VI (US Pharmacopoeia), EC 1935/2004 Regulation, Journal officiel de la Republique Française brochure 1227.
Non porous Surface: Non adherent to most products and adhesives, silicone is water repellent and water- proof.
Dielectric properties: Silicone rubbers are one of the best electric insulators with the possibility of working from -40 ºC to +180 ºC. We can supply special conductive silicone formulations.
Mechanical properties: Compared to other organic elastomers, silicone does not stand out for its mechanical properties, but combined with its high temperature resistance it is unbeaten by other rubbers. We have specific formulations for high mechanical strength, abrasion resistance, high elasticity, high tear strength, etc.
Weather resistance: Offers excellent resistance to all weather conditions, ozone, pyralene and UV radiation.
Chemical resistance: Silicone rubbers have a good response when in contact with most chemical compounds, but are affected by fats, solvents and petrols.
With fluorosilicones we obtain superb anticorrosion results in most conditions.
Colours: Standard silicone is translucent, but can be pigmented with foodstuff contact approved colours to achieve any RAL upon request. We can also supply luminescent, fluorescent and metallic colours. We transform platinum- cured silicones for those items exposed to sun rays, that need a high transparency or to avoid yellowing due to ageing.
Vulcanisation: Silicone rubbers are vulcanised with different catalysts depending on the process used to vulcanise them. The most common catalysts are:
DBPH (2,5-Dimethyl-2,5-di (tert-butylperoxy) hexane), mostly used for moulding.
DCBP (2,4-dichlorobenzoyl peroxide)
and addition catalysts commonly known as platinum curing, being especially suited for medical, pharmaceutical applications and foodstuff contact used in extrusion.
Post-curing: Peroxide- or platinum-cured silicones must be post-cured at +200 ºC for a minimum of ten hours in air recirculating ovens to remove all volatile residues and make them suitable for foodstuff contact, as well as certifiable as medical grade.
Hardness and density: We offer from 25 Shore A to 90 Shore A hardness in compact silicone(our standard being 65 Shore) and 0.25 gr/cm3 to 0.8 gr/cm3 density in sponge silicones (our standard is 0.25 gr/cm3). 20 shore A compact silicones and 0.15 gr/cm3 are in development and approval stages.
Main products and shapes: Tubes, reinforced tubes, hoses, cords, profile, flat die-cut gaskets, moulded seals, inflatable seals, heat-vulcanised seals, encapsulated o-rings, rectangular profiles, square profiles, moulded parts, sheets, rolls, with textile or metal inserts, multicomponent parts, etc.
Main applications: Pharmaceutical, chemical, medical, aeronautics, space industries, laboratories, foodstuff, cosmetics, packaging, fluids, metal carpentry, construction, lighting, electronics, car industry, machinery manufacturing, etc.
Renowned chemist Frederick Kipping was a pioneer in the study of organic compounds with carbon and silicon molecules and was responsible for the name 'silicone'. Silicone is a combination of quartz rock and carbon at high temperatures, obtaining a silicon-based rubber. From this basic substance other physical states such as gels, oils and solids are formed.
Silicone has a high transparency, is versatile and has an excellent behaviour in different physical and chemical working conditions. It can be transformed by injection, compression moulding, extrusion, autoclave, casting, etc.
Thermal Resistance: Silicone rubberus have an excellent behaviour and stability at temperatures from -55 ºC up to +225 ºC and our THT silicones can work up to +320 ºC in dry heat. There are silicones which can reach working temperatures of -90 ºC, such as the Phenyl-Vinyl-Methyl-Siloxanes (PVMQ). We have special vapour resistant (wet heat) silicones which are stable up to +150 ºC constant temperature.
Non toxicity standards:Inert material which can comply the following international standards for medical, pharmaceutical and foodstuff contact:: FDA CFR 177.2600 (US Food and DrugAdministration), BgVVBfR cap.15 (Bundesinstitut für Gesundheitlichen Verbraucherschutz Und Veterinärmedizin), USP Clase VI (US Pharmacopoeia), EC 1935/2004 Regulation, Journal officiel de la Republique Française brochure 1227.
Non porous Surface: Non adherent to most products and adhesives, silicone is water repellent and water- proof.
Dielectric properties: Silicone rubbers are one of the best electric insulators with the possibility of working from -40 ºC to +180 ºC. We can supply special conductive silicone formulations.
Mechanical properties: Compared to other organic elastomers, silicone does not stand out for its mechanical properties, but combined with its high temperature resistance it is unbeaten by other rubbers. We have specific formulations for high mechanical strength, abrasion resistance, high elasticity, high tear strength, etc.
Weather resistance: Offers excellent resistance to all weather conditions, ozone, pyralene and UV radiation.
Chemical resistance: Silicone rubbers have a good response when in contact with most chemical compounds, but are affected by fats, solvents and petrols.
With fluorosilicones we obtain superb anticorrosion results in most conditions.
Colours: Standard silicone is translucent, but can be pigmented with foodstuff contact approved colours to achieve any RAL upon request. We can also supply luminescent, fluorescent and metallic colours. We transform platinum- cured silicones for those items exposed to sun rays, that need a high transparency or to avoid yellowing due to ageing.
Vulcanisation: Silicone rubbers are vulcanised with different catalysts depending on the process used to vulcanise them. The most common catalysts are:
DBPH (2,5-Dimethyl-2,5-di (tert-butylperoxy) hexane), mostly used for moulding.
DCBP (2,4-dichlorobenzoyl peroxide)
and addition catalysts commonly known as platinum curing, being especially suited for medical, pharmaceutical applications and foodstuff contact used in extrusion.
Post-curing: Peroxide- or platinum-cured silicones must be post-cured at +200 ºC for a minimum of ten hours in air recirculating ovens to remove all volatile residues and make them suitable for foodstuff contact, as well as certifiable as medical grade.
Hardness and density: We offer from 25 Shore A to 90 Shore A hardness in compact silicone(our standard being 65 Shore) and 0.25 gr/cm3 to 0.8 gr/cm3 density in sponge silicones (our standard is 0.25 gr/cm3). 20 shore A compact silicones and 0.15 gr/cm3 are in development and approval stages.
Main products and shapes: Tubes, reinforced tubes, hoses, cords, profile, flat die-cut gaskets, moulded seals, inflatable seals, heat-vulcanised seals, encapsulated o-rings, rectangular profiles, square profiles, moulded parts, sheets, rolls, with textile or metal inserts, multicomponent parts, etc.
Main applications: Pharmaceutical, chemical, medical, aeronautics, space industries, laboratories, foodstuff, cosmetics, packaging, fluids, metal carpentry, construction, lighting, electronics, car industry, machinery manufacturing, etc.
Technical Data Sheet
| Propierties | Standard | Units | 135 | 160 | 175 | 180 | |
|---|---|---|---|---|---|---|---|
|
General Characteristics |
Appearance | Transparent | |||||
| Density | ISO R1183 | (g/cm3) | 1,11 | 1,14 | 1,18 | 1,21 | |
| Heat stability | Good heat stability up to + 200°C | ||||||
|
Mechanical propierties after cure |
Catalyst type | Peroxide | |||||
| Catalyst content (parts) | 1,1 | 1,25 | 1,25 | 1,25 | |||
| Post cure | 4 hours at 200 °C | ||||||
| Hardness Shore A | ASTM D 2240 | 41 | 62 | 75 | 81 | ||
| Tensile strength | ISO R37 | (MPa) | 8,2 | 11 | 9,3 | 9 | |
| Elongation at break | ISO R37 | (%) | 420 | 385 | 260 | 200 | |
| Secant modulus at 100% elongation | ASTM D 412 | (MPa) | 1,1 | 2,2 | 3,4 | 5,3 | |
| Tear strength | ASTM D 624A | (kN/m) | 17 | 21 | 21 | 19 | |
| Compresion set
(22h/177°C/25%) |
ASTM D 395B | (%) | 39 | 35 | 37 | 49 | |
| Rebound Resilience | ISO 4662 | (%) | 53 | 53 | 45 | 46 | |
| Linear shrinkage | (%) | 3,1 | 2,6 | ||||
|
Dielectric Propierties After cure |
Dielectric strength (1mm thickness) | kV/mm | 29 | ||||
| Dielectric strength (2mm thickness) | kV/mm | 21 | |||||
| Breakdown voltage | Kv | ||||||
| Dielectric constant | 2,5 | ||||||
| Dissipation factor | 3,4 x 10-3 | ||||||
| Transversal resistivity | Ohm·cm | 2,6 x 1015 | |||||
| Propierties | Standard | Units | 345 | 360 | 370 | |
|---|---|---|---|---|---|---|
|
General Characteristics |
Appearance | Transparent | ||||
| Density | ISO R1183 | (g/cm 3) | 1,1 | 1,16 | 1,18 | |
| Heat stability | Good heat stability up to + 200°C | |||||
|
Mechanical propierties after cure |
Catalyst type | Peroxide | ||||
| Catalyst content (parts) | 1 | 1,25 | 1 | |||
| Post cure | 4 hours at 200 °C | |||||
| Hardness Shore A | ASTM D 2240 | 45 | 62 | 70 | ||
| Tensile strength | ISO R37 | (MPa) | 7,2 | 9 | 9,3 | |
| Elongation at break | ISO R37 | (%) | 460 | 430 | 440 | |
| Secant modulus at 100% elongation | ASTM D 412 | (MPa) | 1,2 | 2,6 | 2,9 | |
| Tear strength | ASTM D 624A | (kN/m) | 31 | 35 | 40 | |
| Compresion set
(22h/177°C/25%) |
ASTM D 395B | (%) | 42 | 48 | 52 | |
| Rebound Resilience | ISO 4662 | (%) | 48 | 47 | 36 | |
| Linear shrinkage | (%) | 3,2 | 3,4 | 3,3 | ||
| Dielectric Propierties After cure |
Dielectric strength | kV/mm | ||||
| Breakdown voltage | kV | |||||
| Dielectric constant | ||||||
| Dissipation factor | ||||||
| Transversal resistivity | Ohm·cm | |||||
| Propierties | Standard | Units | 940 | 950 | 960 | 970 | 980 | |
|---|---|---|---|---|---|---|---|---|
|
General Characteristics |
Appearance | Translucent | Transparent | Translucent | ||||
| Density | ISO R1183 | (g/cm 3) | 1,11 | 1,11 | 1,15 | 1,17 | 1,18 | |
| Heat stability | 225 °C | 200 °C | 200 °C | 225 °C | 200 °C | |||
| Thermal Conductivity | (W/ºC·m) | 0,25 | ||||||
|
Mechanical propierties after cure |
Catalyst type | Peroxide | ||||||
| Catalyst content (parts) | 1,25 | 1,25 | 1,25 | 1,25 | 1,25 | |||
| Post cure | 4 hours at 200 °C | |||||||
| Hardness Shore A | ASTM D 2240 | 46 | 50 | 61 | 70 | 78 | ||
| Tensile strength | ISO R37 | (MPa) | 7,8 | 7,4 | 7,0 | 8,3 | 8 | |
| Elongation at break | ISO R37 | (%) | 515 | 365 | 250 | 350 | 230 | |
| Secant modulus at 100% elongation | ASTM D 412 | (MPa) | 1 | 1,5 | 2,25 | 2,3 | 3,8 | |
| Tear strength | ASTM D 624A | (kN/m) | 13 | 13 | 11 | 18 | 16 | |
| Compresion set
(22h/177°C/25%) |
ASTM D 395B | (%) | 27 | 34 | 25 | 42 | 34 | |
| Rebound Resilience | ISO 4662 | (%) | 61 | 56 | 57 | 54 | 60 | |
| Linear shrinkage | (%) | 2,8 | 2,8 | 2 | 3 | |||
|
Dielectric Propierties After cure |
Dielectric strength | kV/mm | 19 | 23 | 21 | 23 | ||
| Breakdown voltage | kV | 45,4 | 45 | 44 | ||||
| Dielectric constant | 2,8 | 2,8 | 2,8 | 2,9 | ||||
| Dissipation factor | 0,007 | 3,5 x 10 -3 | 3,5 x 10 -3 | 3 x 10 -3 | ||||
| Transversal resistivity | Ohm·cm | 2 x 10 14 | 2,2 x 10 14 | 2,2 x 10 14 | 1,2 x 10 15 | |||
| Propierties | Standard | Units | White Silicone | |
|---|---|---|---|---|
|
General Characteristics |
Appearance | White | ||
| Density | BS-EN-ISO 845 | g/cm 3 | 0,250±0,040 | |
| Heat stability | ºC | -50ºC / +200ºC | ||
| Hardness Shore OO | ASTM D2240 | 45±5 | ||
| Hardness Shore A | ASTM D2240 | 5±2 | ||
|
Mechanical propierties after cure |
Compresion stress | BS-EN-ISO 3386 parte 1.2 | kPa | 90±40 |
| Tensile strength | BS-EN-ISO 1798 (0,75min.) | N.mm -2 | 1,2 | |
| Tear strength | BS-EN-ISO1798 (100min.) | % | 200 | |
| Compresion set | BS-EN-ISO 1856 (22h/70ºC) | % | 10 | |
| Brittle point | ASTM D746 | ºC | -80 | |
| Oxygen limit index | BS 2872 Parte 1 | % | 24 | |
| Thermal Conductivity | VDE 0304 | W.m -1.K -1 | 0,24 | |
| Radiation Resistance | >10 5 Grays (10 5 Rads) | |||
|
Dielectric Propierties After cure |
Dielectric Coefficient | VDE 0303 | 2,9 | |
| Dielectric strength | VDE 0303 | kV.mm -1 | 23 | |
| Dissipation factor at 50c/s | VDE 0303 | 3x10 -4 | ||
| Volume Resistivity | VDE 0303 | 3x10 15 Ohm.cm |
Chemical Resistance Chart
| Acid | Resistance | |
|---|---|---|
| Acetic acid 5% | Good | |
| Concentrated acetic acid | Good | |
| Hydrochloric acid 10% | Good | |
| Concentrated Hydrochloric acid | Good | |
| Chromic acid 10% | Good | |
| Chromic acid 50% | Good | |
| Citric acid | Good | |
| Formic acid below 87% | Good | |
| Nitric acid 10% | Good | |
| Concentrated nitric acid | Mediocre | |
| Oleic acid | Good | |
| Oxalic acid | Good | |
| Phosphoric acid 10% | Good | |
| Concentrated Phosphoric acid | Quite good | |
| Stearic acid | Good | |
| Sulphuric acid 10% | Good | |
| Concentrated Sulphuric acid | Bad | |
| Alkali | Resistance | |
|---|---|---|
| Ammonia 10% | Good | |
| Concentrated Ammonia | Good | |
| Potash 10% | Good | |
| Potash 50% | Good | |
| Caustic Soda 10% | Good | |
| Caustic Soda 50% | Good |
| Saline Solution | Resistance | |
|---|---|---|
| Ammonium acetate | Good | |
| Ammonium carbonate | Good | |
| Barium chloride | Good | |
| Calcium carbonate | Good | |
| Calcium chloride | Good | |
| Calcium Hypochlorite | Good | |
| Iron sulphate | Good | |
| Potassium chloride | Good | |
| Sodium disulphate | Good | |
| Sodium disulphite | Good | |
| Sodium carbonate 2% | Good | |
| Sodium chloride below 23% | Good | |
| Sodium cianide | Good | |
| Sodium trisulphate | Good |
| Solvent | Resistencia | |
|---|---|---|
| Butyl acetate | Quite good | |
| Acetone | Quite good | |
| Amyl Alcohol | Good | |
| Butyl Alcohol | Quite good | |
| Isoprolylic Alcohol | Mediocre | |
| Methyl Alcohol | Good | |
| Diacetone Alcohol | Mediocre | |
| Essence | Mediocre | |
| Turpentine | Mediocre | |
| Ether | Mediocre | |
| Carbon tetrachloride | Mediocre | |
| White Spirit | Mediocre |
| Agent | Resistance | |
|---|---|---|
| Liquid ammonia | Good | |
| Aniline | Good | |
| Phthalic anhydride | Good | |
| Sulphur anhydride | Mediocre | |
| Bromium | Quite good | |
| Chlorine | Good | |
| Chlorine water | Good | |
| Phtalic dibutyl | Good | |
| Dichlorobenzene | Good | |
| Diphenyl chloride | Good | |
| Water at room temperature | Good | |
| Boiling water | Good | |
| Water vapour | Good | |
| Hydrogen peroxide 80-85% | Good | |
| Ethylene glycol | Good | |
| Ethylene oxide | Good | |
| Freon 12 | Mediocre | |
| Freon 114 | Mediocre | |
| Glicerine | Good | |
| Methyl chloride | Mediocre | |
| Nitrocellulose | Good | |
| Paraffin | Mediocre | |
| Pentachlorophenol 10% (in alcohol) | Good | |
| Phenol 85% | Good | |
| Phosphate trichloride | Mediocre | |
| Silicon Tetrachloride | Mediocre | |
| Tricresyl phosphate | Good |
Tolerances
During silicone rubber extrusion processes, the tolerances needed are higher than during moulding as when silicone is extruded and goes through the die it expands and during vulcanisation and post-curing it contracts and deforms.
The deformation at the exit of the extruder can be controlled via different supports, which in turn will depend of the degree of control, size and cross-section required. The characteristics of the profile will determine the tolerances applicable to each dimension. With certain synthetic rubbers it is not possible to achieve E1 class.
During longitudinal cutting, precision and tolerance will be dependent on the technology used in the process.
During moulding, all parts are manufactured with an excess of rubber to fill the shape completely and the excess material flashes. This flash makes the vertical dimensions (thickness) vary. To apply the standard correctly, we have to take into consideration the fixed dimensions which are: horizontal (H) and thickness (V), vertical. For vertical tolerances you need to use the highest dimension of the part.
There are 3 types if internationally accepted tolerances: E for extrusion, L for longitudinal cut and M for moulding:
- Class E1, L1 and M1 = Maximum Quality
- Class E2, L2 and M2 = Good Quality
- Class E3, L3 and M3 = Not Critical
- Class M4 = Medium Quality
| from(mm) | to(mm) | Clase E1(+ / - mm) | Clase E2(+ / - mm) | Clase E3(+ / - mm) | |
|---|---|---|---|---|---|
| Nominal Dimension |
0 | 1,5 | 0,15 | 0,25 | 0,40 |
| 1,5 | 2,5 | 0,20 | 0,35 | 0,50 | |
| 2,5 | 4,0 | 0,25 | 0,40 | 0,70 | |
| 4,0 | 6,3 | 0,35 | 0,50 | 0,80 | |
| 6,3 | 10 | 0,40 | 0,70 | 1,00 | |
| 10 | 16 | 0,50 | 0,80 | 1,30 | |
| 16 | 25 | 0,70 | 1,00 | 1,60 | |
| 25 | 40 | 0,80 | 1,30 | 2,00 | |
| 40 | 63 | 1,00 | 1,60 | 2,50 | |
| 63 | 100 | 1,30 | 2,00 | 3,20 |
| from(mm) | to(mm) | Clase L1(+ / - mm) | Clase L2(+ / - mm) | Clase L3(+ / - mm) | |
|---|---|---|---|---|---|
| Nominal Length |
0 | 40 | 0,70 | 1,00 | 1,60 |
| 40 | 63 | 0,80 | 1,30 | 2,00 | |
| 63 | 100 | 1,00 | 1,60 | 2,50 | |
| 100 | 160 | 1,30 | 2,00 | 3,20 | |
| 160 | 250 | 1,60 | 2,50 | 4,00 | |
| 250 | 400 | 2,00 | 3,20 | 5,00 | |
| 400 | 630 | 2,50 | 4,00 | 6,30 | |
| 630 | 1000 | 3,20 | 5,00 | 10,00 | |
| 1000 | 1600 | 4,00 | 6,30 | 12,50 | |
| 1600 | 2500 | 5,00 | 10,00 | 16,00 | |
| 2500 | 4000 | 6,30 | 12,50 | 20,00 | |
| 4000 | --- | 0,16% | 0,32% | 0,50% |
| from(mm) | to(mm) | Clase M1V (+ / - mm) H | Clase M2V (+ / - mm) H | ClaseM3V (+ / - mm) H | Clase M4F(+/- mm)H | ||||
|---|---|---|---|---|---|---|---|---|---|
| Nominal Dimension |
0 | 4 | 0,08 | 0,10 | 0,10 | 0,15 | --- | --- | --- |
| 4 | 6,3 | 0,1 | 0,12 | 0,15 | 0,20 | 0,25 | 0,40 | 0,50 | |
| 6,3 | 10 | 0,10 | 0,15 | 0,20 | 0,20 | 0,30 | 0,50 | 0,70 | |
| 10 | 16 | 0,15 | 0,20 | 0,20 | 0,25 | 0,40 | 0,60 | 0,80 | |
| 16 | 25 | 0,20 | 0,20 | 0,25 | 0,35 | 0,50 | 0,80 | 1,00 | |
| 25 | 40 | 0,20 | 0,25 | 0,35 | 0,40 | 0,60 | 1,00 | 1,30 | |
| 40 | 63 | 0,25 | 0,35 | 0,40 | 0,50 | 0,80 | 1,30 | 1,60 | |
| 63 | 100 | 0,35 | 0,40 | 0,50 | 0,70 | 1,00 | 1,60 | 2,00 | |
| 100 | 160 | 0,40 | 0,50 | 0,70 | 0,80 | 1,30 | 2,00 | 2,50 | |
| 160 | --- | 0,3% | 0,4% | 0,5% | 0,7% | 0,8% | 1,30% | 1,50% | |
| from(mm) | to(mm) | Tolerance(+ / - mm) | |
|---|---|---|---|
| NominalDimension | 1,6 | 7,00 | 0,50 |
| 7,50 | 10,00 | 0,80 | |
| 11,00 | 11,50 | 1,00 | |
| >11,50 | 17,00 | 1,50 | |
| >17,00 | 19,00 | 1,90 | |
| >19,00 | 20,00 | 2,00 | |
| >20,00 | 25,00 | 1,60 |
