| HS Code | 513799 |
| Chemical Composition | Vinyl-functional silicone resin |
| Appearance | Colorless to light-yellow transparent liquid |
| Solid Content | 60 ± 2% |
| Viscosity At 25 C | 2000–5000 mPa·s |
| Vinyl Content | 2.0–3.0 wt% |
| Density At 25 C | 1.03–1.08 g/cm³ |
| Refractive Index At 25 C | 1.40–1.42 |
| Solvent | Toluene/xylene |
| Flash Point | ≥40°C |
| Curing Mechanism | Platinum-catalyzed addition curing |
| Volatile Content | ≤2% |
| Thermal Stability | High-temperature resistant after cure |
| Storage Stability | 6–12 months in sealed container |
| Shelf Life | 12 months |
As an accredited Vinyl Silicone Resin S605-3 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Vinyl Silicone Resin S605-3 is supplied in 25 kg sealed industrial drums, suitable for safe storage and transport. |
| Container Loading (20′ FCL) | 20′ FCL loading: Vinyl Silicone Resin S605-3 in sealed, labeled drums/pails, palletized, evenly distributed, and securely lashed for transport. |
| Shipping | Ship Vinyl Silicone Resin S605-3 in original, sealed, labeled containers protected from moisture, heat, and ignition sources. Store in a cool, dry, well-ventilated area. Verify current SDS for hazardous classification; solvent-containing grades may require flammable-liquid packaging and UN markings. |
| Storage | Store Vinyl Silicone Resin S605-3 in a cool, dry, well-ventilated area away from direct sunlight, heat sources, sparks, and open flames. Keep containers tightly closed when not in use and protect from moisture and contamination. Store separately from strong oxidizers, acids, and alkalis. Use appropriate secondary containment and follow local regulations and the manufacturer’s safety data sheet. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored in original unopened containers in a cool, dry, well-ventilated place. |
During platinum-catalyzed addition-cure liquid silicone rubber injection molding, S605-3 is metered as a pre-blended vinyl-functional reinforcing resin rather than as a primary polymer. A production-scale LSR system running on a 25 mm plasticizing screw with 20 MPa injection pressure and 800 kN to 1,500 kN clamp force uses S605-3 pre-dispersed in a 0.5 Pa·s vinyl-terminated polydimethylsiloxane at 60 °C. The dispersion is filtered through a 200-mesh inline screen before being combined with the base gum, hydride crosslinker, and platinum catalyst in a static mixer. Addition levels lie between 20 phr and 40 phr when calculated against 100 parts of 20 Pa·s vinyl-terminated polydimethylsiloxane. Below 20 phr, tear strength measured on 2 mm sheets according to ISO 37:2017 Type 2 specimens drops after 70 h at 180 °C. Above 40 phr, compound viscosity rises beyond 250 Pa·s at 10 s⁻¹, which impairs molding of thin-walled parts with cross sections under 0.5 mm. Cure is initiated at 120 °C for 60 s in the mold, followed by forced-air post-cure at 200 °C for 4 h. Post-cured Shore A hardness is determined by ISO 7619-1:2019 and compression set by ISO 815-1:2019, Method A, after 22 h at 150 °C. Terminal articles include peristaltic pump diaphragms and infant care valve bodies. Medical-grade batches require extraction testing under ISO 10993-12:2021 and cytotoxicity under ISO 10993-5:2009. Food-contact uses are assessed under FDA 21 CFR 177.2600 for repeated-use rubber articles. The resin should not be mixed with amine-containing silane adhesion promoters because amine residues quench platinum activity and produce tacky undercured surfaces.
Optical transmittance in chip-on-board LED encapsulants is controlled by refractive index mismatch and MQ-domain scattering. S605-3 is blended at 5 wt% to 15 wt% with a divinyl dimethylsiloxane having a refractive index of 1.41 at 589 nm. Mixing is performed in a planetary vacuum mixer at 800 Pa and 1,200 min⁻¹ for 15 min to reduce dissolved air below visual bubble threshold. A hydride crosslinker is added at a SiH/Vi ratio of 1.2 to 1.8, and platinum catalyst concentration is held at 5 ppm to 15 ppm metal. The liquid is dispensed through a 30 gauge needle onto phosphor-coated LED chips. Step cure begins at 80 °C for 1 h, then 150 °C for 2 h. Luminous transmittance through a 2 mm cured disk is measured at 450 nm according to ASTM D1003-21. Hardness rises from Shore A 25 to Shore A 60 as S605-3 increases from 5 wt% to 15 wt%. Adhesion to silver-plated lead frames is checked by JEDEC JESD22-A101 after 85 °C and 85% relative humidity for 1,000 h. Sulfur-emitting silver adhesive residues must be excluded from the package because sulfur poisons the platinum catalyst and inhibits cure. Terminal uses include COB LED modules, automotive interior light bars, and horticultural lamp arrays where lumen maintenance above 90% after 3,000 h is a production acceptance gate.
| Application segment | Governing standard or method | Endpoint or condition | End market |
|---|---|---|---|
| LSR injection molded parts | ISO 10993-5:2009 | Cytotoxicity, extract dilution | Medical devices |
| Repeated-use rubber articles | FDA 21 CFR 177.2600 | Extraction limits | Food-contact seals |
| Label release liners | FDA 21 CFR 175.320 | Olefin polymer coatings | Packaging |
| Food-label PSA | FDA 21 CFR 175.105 | Adhesive components | Food labels |
| LED encapsulant | ASTM D1003-21 | Haze/luminous transmittance at 450 nm | Automotive lighting |
| Power module gel | IEC 60068-2-14 | Thermal cycling Test Na 1,000 cycles | Electric bus traction |
For solvent-borne silicone pressure-sensitive masking tapes, S605-3 functions as a condensed vinyl-rich co-resin in a polyimide-film adhesive system. The adhesive solids contain 20 wt% to 50 wt% S605-3, 20 wt% to 40 wt% silanol-terminated gum, and the balance MQ resin. The mixture is dissolved in toluene and xylene at 25 wt% solids and coated onto 50 μm polyimide film with a comma coater at 15 m/min. Drying proceeds in three zones at 80 °C, 110 °C, and 130 °C until residual solvent drops below 500 ppm by headspace gas chromatography using ASTM D5407-19. The dry adhesive is post-cured at 150 °C for 2 min to build cohesive strength. Loop tack is measured according to FINAT FTM 9, 180° peel according to FINAT FTM 1, and static shear according to ASTM D3654-19, Procedure A, with a 1 kg load at 70 °C. Terminal use is masking during plasma-spray coating of turbine blades, where the tape must remain dimensionally stable at 180 °C for 4 h. Food-contact adhesive applications require extraction limits under FDA 21 CFR 175.105. Benzoyl peroxide should not be used as a co-initiator in this formula, because acidic decomposition by-products interact with S605-3 and cause premature gelation in the coating bath after 8 h.
A solventless release coating for filmic label liners balances two opposing constraints on S605-3: crosslink density must produce differential release below 8 cN/25 mm, while the coating bath must retain at least 80% of initial platinum activity after 24 h standing at 35 °C. In this application, S605-3 is incorporated at 3 wt% to 8 wt% into a vinyl-functional base polymer with a hydride crosslinker at SiH/Vi ratio of 1.8 to 2.6. Catalysis is supplied by a platinum-divinyltetramethyldisiloxane complex at 50 ppm to 120 ppm metal. The bath is coated on 36 μm polyester film at 250 m/min using five-roll gravure coating. Curing occurs in a nitrogen-fired oven at 150 °C for 5 s. Release force is measured 1 day after treatment with TESA 7475 tape according to FINAT FTM 3, and subsequent adherence is checked by FINAT FTM 11. Higher S605-3 loading increases release force and reduces loop tack of labels. The release liner is supplied to hot-melt label laminators and supports casting of acrylic label adhesives. Food-contact status is assessed under FDA 21 CFR 175.320 for olefin polymer coatings and under BfR Recommendation XXXVI for silicone release papers. Addition of acetylenic inhibitors such as 1-ethynyl-1-cyclohexanol at 0.05 wt% to 0.3 wt% extends bath life without lowering cured rub test resistance.
On a 16-inch two-roll mill with apron warming, roll temperature set to 25 °C to 35 °C, and nip gap adjusted to 1.5 mm, S605-3 is added as a liquid resin during the first 3 min of gum softening. The resin is incorporated at 2 phr to 12 phr relative to 100 parts of vinyl gum. Fumed silica with BET surface area of 200 m²/g is added after the resin at 30 phr to 50 phr and dispersed for 20 min at a friction ratio of 1.2:1. Temperature control is critical above 40 °C, where S605-3 can migrate to the roll surface and create a slipping layer. The compound is catalyzed with 0.6 phr to 1.2 phr of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and compression molded at 170 °C for 10 min under 15 MPa. Post-cure is performed at 200 °C for 4 h. Tensile strength and elongation at break are measured according to ASTM D412-16, Die C; tear strength according to ASTM D624-20, Die B; hardness according to ASTM D2240-15, Shore A. Terminal products include turbocharger air ducts and oven door gaskets. For such articles, formulations are evaluated under ISO 188:2011 for hot air aging at 200 °C for 168 h. The resin is not recommended for food-contact HTV applications unless post-cured to meet FDA 21 CFR 177.2600 extraction limits.
When addition-cure silicone gel encapsulants for traction power modules must survive thermal cycling from -40 °C to 125 °C, S605-3 is used at 5 wt% to 15 wt% in the gel precursor blend to increase crosslink density without building a glassy network. The precursor is mixed with a hydrogen methylsiloxane crosslinker at SiH/Vi ratio of 0.8 to 1.4 and a platinum catalyst at 5 ppm to 20 ppm metal. Degassing is conducted at 100 Pa until visible bubble collapse ceases, then the liquid is dispensed into insulated gate bipolar transistor housings. Cure is staged at 70 °C for 30 min and 100 °C for 60 min. Gel hardness is measured with a Shore OO durometer according to ASTM D2240-15 and dielectric strength according to ASTM D149-20 at 1 mm thickness. Thermal cycling is validated according to IEC 60068-2-14, Test Na, with 1,000 cycles from -40 °C to 125 °C at 3 °C/min. Terminal articles are traction motor power modules for electric buses where partial discharge resistance under high switching frequency is a production acceptance gate. The system has a working temperature ceiling of 200 °C in continuous dry use; above 220 °C, silicone depolymerization under confined-space pyrolysis can generate volatile cyclic siloxanes.
In airbag seam coating for 470 dtex polyamide fabric, S605-3 is applied in a low-viscosity solventless formulation where knife-over-roll coating must penetrate the weave without strike-through. The coating fluid consists of 10 phr to 20 phr S605-3 in vinyl-terminated dimethylpolysiloxane with a 5,000 mPa·s viscosity, fumed silica at 0.5 phr to 2 phr as thixotrope, hydride crosslinker at SiH/Vi 1.4 to 2.0, and platinum at 10 ppm to 25 ppm. It is applied with a knife gap of 0.3 mm at 12 m/min. Cure is carried out at 160 °C for 2 min in a stenter frame. The cured coating is tested for flexibility by ISO 5981:2017 after 500 cycles. Hydrolytic stability is measured after immersion in 80 °C water for 168 h according to ISO 105-E01. Terminal applications are side-curtain airbag baffles and seatbelt webbing edge coatings. The addition level must not exceed 25 phr because higher resin content reduces seam elongation and increases tunnel fraying at laser-cut edges. The wet fabric must be free of condensation agents such as dibutyltin dilaurate, since tin residues catalyze siloxane redistribution and destabilize the coating bath.
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Vinyl Silicone Resin S605-3 is a vinyl-functional MQ silicone resin supplied for hydrosilylation-cure polydimethylsiloxane formulations in which elevated network density, optical clarity, and controlled shrinkage are specified. The S605-3 designation identifies a resin with a mid-range vinyl substitution level. Typical lot-release data for this product class include vinyl content 2.8–3.5 wt% by iodometric titration, viscosity 5,000–15,000 mPa·s at 25°C by ASTM D2196 rotational viscometry, and non-volatile content ≥98.5% after 2 h at 150°C. Unlike a linear vinyl-terminated reactive diluent, S605-3 contributes Q-branch point density and M-unit chain termination to the siloxane network. That structural contribution changes tensile modulus, tear resistance, and Shore hardness in a manner distinct from vinyl-terminated polydimethylsiloxane fluids.
In addition-cure elastomers, S605-3 is introduced during the low-shear stage using a planetary mixer or high-speed disperser. Production-scale batches processed in a 50 L planetary mixer with vacuum capability of ≤ -0.095 MPa have been dispersed into 1,000 mPa·s vinyl-terminated PDMS at 60°C for 30 min. Transparent intermediates were maintained below 40 wt% loading; above 70 wt% the system exceeded 50,000 mPa·s and required a three-roll mill to avoid starved mixing at the agitator. The resin should not be processed at high ambient humidity without pre-drying at 80°C for 2 h. Residual water above 300 ppm can reduce platinum catalyst activity and produce microvoids during cure, measurable as optical haze under ISO 13468-1.
Methyl MQ resins are largely unreactive in hydrosilylation networks unless vinyl-functional fluids are present. Unreacted methyl MQ can migrate to the surface during thermal aging because it is not covalently bound to the crosslinked matrix. S605-3 supplies pendant vinyl groups at the resin surface, enabling covalent attachment to the PDMS network. This reduces extractables after cure and stabilizes hardness retention after 1,000 h at 150°C, as evaluated by ASTM D2240 and toluene extraction following ASTM D5289.
High-vinyl MQ grades with vinyl content above 6 wt% generate very high crosslink density, but they can narrow the processing window and produce brittle fracture at elevated loading. S605-3 provides a mid-range vinyl content that creates a lower viscosity build and a longer usable pot life at equivalent platinum catalyst dose. In comparative formulation work using 30 phr resin in a 1,000 mPa·s vinyl-terminated PDMS cured with 5 ppm platinum at 150°C for 1 h, S605-3 shifted the tensile profile toward higher elongation and lower modulus relative to a high-vinyl MQ. The directional effect is consistent with reduced crosslink density, but published data for this specific S605-3 configuration in identical substitution trials remains supplier-specific.
| Resin type | Shore A hardness | Tensile strength, MPa | Elongation at break, % | Mix viscosity increase, mPa·s |
|---|---|---|---|---|
| Methyl MQ, vinyl <0.1 wt% | 55 | 3.2 | 120 | 4,000 |
| S605-3, vinyl 3.0 wt% | 72 | 5.4 | 95 | 8,500 |
| High-vinyl MQ, vinyl 6.5 wt% | 85 | 6.5 | 40 | 18,000 |
The comparative data above are representative of a 30 phr loading in 1,000 mPa·s vinyl-terminated PDMS with 5 ppm platinum catalyst and cure at 150°C for 1 h. The S605-3 system balances hardness and elongation without the pot-life collapse typical of high-vinyl MQ grades. This is the principal formulation rationale for selecting S605-3 over fully methyl or densely vinyl-functional MQ resins.
The batch-release framework for S605-3 should be coordinated with the resin supplier because lot-to-lot variation in vinyl distribution and residual volatiles can affect cure rheology. The following matrix is used for incoming inspection in silicone compounding operations. Values are typical of the product class and do not replace the certificate of analysis.
| Property | Test method | Typical limit or range | Unit |
|---|---|---|---|
| Appearance | Visual, 25°C | Clear to pale yellow liquid | — |
| Vinyl content | Iodometric titration | 2.8–3.5 | wt% |
| Viscosity | ASTM D2196 | 5,000–15,000 | mPa·s |
| Volatile content | 2 h at 150°C | ≤1.5 | wt% |
| Refractive index | ASTM D1218, 25°C | 1.406–1.416 | — |
| Specific gravity | ASTM D4052 | 0.98–1.02 | — |
| Pt catalyst compatibility | Visual after 24 h at 40°C with 5 ppm Pt | No gelation | — |
Raw-material compliance should be confirmed against the relevant regulatory inventory applicable to the end article. For silicone rubbers in repeated food-contact use, verification against FDA 21 CFR 177.2600 and European Union Regulation (EU) 10/2011 migration limits is required. REACH SVHC screening and RoHS Directive 2011/65/EU restricted-substance checks must be performed at the article level because the resin is an intermediate, not a finished material.
LED encapsulant and optical bonding applications impose simultaneous constraints on transmittance, yellowing, and condensable outgassing. S605-3 is used in such systems because the MQ architecture contributes a higher glass-transition temperature without the chain alignment loss of linear PDMS. Luminous transmittance of cured 2 mm specimens has been reported above 92% when measured by ISO 13468-1, provided that platinum and inhibitor concentrations are controlled sufficiently to avoid colloidal haze. Outgassing screening by ASTM E595 at 150°C is recommended with a maximum total mass loss of 0.5% and collected volatile condensable material below 0.1% for optical cavity packages.
In optical-grade formulations, S605-3 must be protected from contamination by amine-containing mold-release agents, sulfur-containing organic compounds, and phosphate-based additives. These species can poison the platinum catalyst or yellow the cured network under 85°C/85% RH aging. Long-term optical stability is commonly assessed by yellowing index change per ASTM E313 after 1,000 h at 150°C; formulations containing S605-3 and a low-alkali platinum catalyst have exhibited a shift of less than 3 yellowing index units when sealed from ambient humidity. The exact shift depends on the base polymer and is not a sole function of the resin.
S605-3 also differs from vinyl-terminated linear fluids in cure shrinkage behavior. In a casting application cured at 150°C for 1 h, volumetric shrinkage measured by ASTM D792 before and after cure was reduced by approximately 1.2 percentage points when 30 wt% of the linear vinyl fluid was replaced with S605-3. This shrinkage reduction is relevant for gap-filling adhesives and optical assemblies where interfacial stress causes delamination. The resin should not be relied upon as the sole shrinkage-control strategy if the formulation contains more than 15 wt% low-molecular-weight reactive diluents because volatile diluent loss can overwhelm the resin contribution.
For high-hardness coatings and adhesives, S605-3 is typically used at 20–60 phr on the vinyl-terminated base polymer. At low additions below 20 phr, hardness increase is measurable but may not justify the cost or viscosity rise. At additions above 60 phr, the mixed compound can become paste-like and requires heated mixing or solvent thinning. The resin should be blended before the platinum catalyst and crosslinker are added, because localized high vinyl concentration can create gel particles when the platinum catalyst encounters an unhomogenized resin-rich zone.
Vacuum degassing parameters depend on batch size and mixer geometry. In a 5 L planetary mixer, degassing at ≤ -0.095 MPa for 10–15 min after resin dispersion removes entrained air and low-molecular-weight volatiles. In high-speed dispersion, tip speed above 15 m/s can generate shear heating above 80°C and should be avoided unless the batch is jacketed. Filtration through 20 µm absolute-rated stainless steel mesh is recommended before dispensing to remove any partially solvated resin particles that survived mixing.
The cure profile should be matched to the Pt concentration and inhibitor package. A starting formulation with 5 ppm platinum and a vinyl-functional silicone inhibitor can achieve gelation in 60–90 s at 120°C, but full hardness development requires a post-cure of 1–2 h at 150°C. Excess catalyst above 10 ppm may accelerate cure exotherm in thick sections and generate yellowing. S605-3 does not cure by moisture and should not be formulated with tin condensation-cure systems unless the vinyl groups are inert in that chemistry. Contact with bare copper, brass, or amine-containing substrates should be evaluated by ASTM D5289 cure rheometry because these substrates can retard or accelerate platinum-catalyzed addition cure in an uncontrolled manner.
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