| HS Code | 192314 |
| Productname | Phenyl Hydrogen Silicone Resin SH303-2B |
| Chemicaltype | Phenyl hydrogen silicone resin |
| Appearance | Colorless to light yellow transparent liquid |
| Stateat25c | Liquid |
| Viscosityat25c | 50-150 mPa·s |
| Densityat25c | 1.05-1.10 g/cm³ |
| Refractiveindexat25c | 1.50-1.53 |
| Hydrogencontent | 0.3-0.5% |
| Solidcontent | ≥98% |
| Volatilecontent | ≤2% |
| Flashpoint | ≥100 °C |
| Reactivegroup | Si-H |
| Solventcontent | Solvent-free / 100% active |
| Shelflife | 12 months in sealed container |
| Storagetemperature | 0-30 °C |
As an accredited Phenyl Hydrogen Silicone Resin SH303-2B factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 25 kg net polyethylene-lined steel drums, or 200 kg net drums, sealed and clearly labeled for chemical storage. |
| Container Loading (20′ FCL) | Phenyl Hydrogen Silicone Resin SH303-2B loaded in a 20′ FCL container, securely packed and sealed for safe transport. |
| Shipping | Phenyl Hydrogen Silicone Resin SH303-2B is shipped in sealed, labeled drums or IBCs under dry, ventilated conditions, protected from moisture, heat, sunlight, and freezing. Keep containers closed, avoid incompatible oxidizers, and transport according to local regulations and the product SDS. |
| Storage | Store Phenyl Hydrogen Silicone Resin SH303-2B in tightly closed original containers in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and open flames. Protect from moisture and keep separate from oxidizing agents, acids, and alkalis. Use appropriate secondary containment, label clearly, and follow local regulations and the supplier’s safety data sheet. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored unopened in original packaging in a cool, dry, well-ventilated place. |
In high-power LED packaging where junction temperature excursions exceed 120 °C and luminous flux density reaches 150 lm/mm², addition-cure silicone encapsulants formulated with phenyl hydrogen silicone resin SH303-2B address two failure acceleration mechanisms simultaneously: refractive index mismatch at the die/silicone interface and thermal oxidative yellowing at the lead-frame wall. The resin is metered as the Si-H crosslinker into a vinyl-terminated phenylmethylsiloxane base polymer at 20–45 wt% of the total liquid formulation, with the final mix adjusted to an Si-H to Si-Vi molar ratio of 1.1:1 to 1.8:1. Ratios above 2.0:1 are not used in production because residual hydride species convert to silanol under 85 °C/85% RH aging and produce hazing at the wire-bond shadow zone; ratios below 1.0:1 leave unreacted vinyl groups that increase compression set after temperature cycling. Production dispensing is performed on planetary centrifugal mixers with vacuum degassing at 5–10 mbar and a pot temperature held below 28 °C; the resulting uncured viscosity window of 2,000–4,500 mPa·s at 25 °C is compatible with needle dispensing into PPA and EMC cavities without void entrapment. Dispensing rooms above 60% RH require nitrogen-blanketed resin reservoirs to prevent viscosity drift and premature hydrolysis of the Si-H group. The cure schedule is typically 100 °C for 1 h followed by 150 °C for 3 h; this staged ramp reduces hydride out-gassing that otherwise causes bubble formation in dam-and-fill, high-power COB arrays. Compliance for the formulated encapsulant is evaluated under IEC 62717:2015 lumen maintenance classes, JEDEC JESD22-A101D steady-state humidity bias, JESD22-A104F temperature cycling, and optical clarity by ASTM D1003-21; hardness is recorded by ISO 868:2003. Terminal finished product types include 2835, 5050, and 7070 LED packages, COB chip-on-board arrays for horticultural and general lighting, and mini-LED backlight modules where the phenyl content stabilizes the refractive index above 1.53 after 1,000 h of wet-thermal aging.
Secondary optics produced from phenyl-silicone thermosets exhibit a characteristic failure sequence under wet-thermal aging: first, unreacted hydride at the polished surface oxidises to silanol; second, silanol condensation increases surface roughness; third, interfacial scattering reduces luminous transmittance even though bulk yellowness index remains stable. SH303-2B is therefore formulated at 10–25 parts per 100 parts of vinyl-functional phenyl T-resin rather than as the sole crosslinker, and the Si-H to Si-Vi molar ratio is held between 1.05:1 and 1.35:1. Higher hydride ratios generate measurable ΔYI drift after 1,000 h at 85 °C/85% RH; lower ratios produce under-cured surfaces that replicate mold chatter. The liquid composition is degassed at 10–20 mbar and cast into polished aluminum or electroformed nickel molds with surface finish Ra below 0.02 µm. Casting humidity above 50% RH produces micro-pitting on the high-gloss surface during cure because airborne moisture reacts with the Si-H donor before the vinyl addition step is complete. Cure is staged at 130 °C for 30 min and 160 °C for 2 h, followed by a 180 °C post-bake of 1 h to consume residual hydride before lens demolding. This sequence is intended for secondary optical components, not for primary die encapsulation. Terminal parts include total internal reflection collimators for streetlight modules, silicone light pipes for automotive daytime running lamps, and cylindrical lens arrays for UV-LED line-irradiation units where the phenyl-rich network maintains dimensional stability under continuous radiant flux.
| Property | Standard | Test Condition | Advisory Acceptance Window |
|---|---|---|---|
| Luminous transmittance | ISO 13468-2:2021 | 2 mm thickness | ≥ 92% at 400–800 nm |
| Yellowness index change | ASTM E313-20 | 1,000 h at 85 °C/85% RH | ΔYI ≤ 1.5 |
| Shore D hardness | ISO 868:2003 | 15 s reading | 60–80 Shore D |
| Adhesion to polycarbonate | ASTM D3359-17 Method B | Cross-cut tape | ≥ 4B |
| Coefficient of linear thermal expansion | ASTM E831-19 | -40 °C to 125 °C | 200–300 ppm/K |
Compression molding trials on two-roll mills with a friction ratio of 1.15:1 show that phenyl hydrogen silicone resin SH303-2B can be compounded into vinyl-functional high-consistency silicone rubber at 3–8 phr without causing mill sticking if the resin is pre-blended with a low-vinyl gum carrier. The addition level is constrained by two process limits: below 3 phr the compression set of the vulcanizate after 70 h at 150 °C exceeds 35% in ASTM D395-18 Method B testing, while above 8 phr the uncured compound viscosity rises beyond the flow window of injection molding machines with clamp force under 200 t. Two-roll mill temperatures above 45 °C generate crusting when platinum catalyst and resin are combined before homogeneous dispersion. The mixed stock is vulcanized in compression presses at 170 °C for 10 min, then oven post-cured at 200 °C for 4 h to remove hydrogen evolved from residual Si-H groups; without post-cure, 0.2–0.4 mm porosity appears in sections thicker than 6 mm. Heat-aging stability is checked against ASTM D573-04 for 72 h at 225 °C, with retained elongation above 50% for phenyl-modified compounds. Compliance documentation references ASTM D2000-18 classification M GE where applicable, ASTM D624-00 die B for tear, and ISO 188:2011 for accelerated aging. Terminal finished product types include turbocharger outlet hose couplers, exhaust gas recirculation gaskets, aerospace firewall grommets, and silicone rubber rollers used in laminating lines where continuous surface temperature exceeds 200 °C.
Adhesive transfer coating at line speeds above 40 m/min produces measurable differences in peel adhesion when SH303-2B is substituted for linear methyl hydrogen polysiloxane as the hydride donor in silicone pressure-sensitive adhesive formulations. The resin is incorporated at 5–15 wt% based on dry adhesive solids, with the Si-H to Si-Vi molar ratio adjusted to 1.2:1 to 1.6:1 because the phenyl-bearing resin retards platinum catalyst activity more strongly than methyl-only crosslinkers. Solvent-borne coatings are applied to corona-treated polyimide film by comma roll or slot-die, then passed through a forced-air oven at 120 °C for 3 min and a final zone at 165 °C for 2 min. The phenyl modification raises the shear adhesion failure temperature measured by ASTM D4498-07 by approximately 20–30 °C compared with dimethylsiloxane controls, but the same modification increases residual hydride after cure if the oven residence time drops below 90 s at 165 °C. Peel adhesion is evaluated by ASTM D3330/D3330M-04 Method A on stainless steel panels, and caliper control follows ASTM D3652/D3652M-01. Release liner selection must exclude tin-catalysed silicones because tin residues deactivate platinum addition cure; amine-catalysed release liners are also incompatible because they promote Si-H hydrolysis and hydrogen blistering during aging, so fluorosilicone-coated liners are used instead. Terminal finished product types include polyimide masking tapes for wave soldering and reflow, high-temperature electrical insulation tapes, and adhesive transfer sheets for bonding silicone sponge gaskets in industrial equipment.
For glass-fiber-reinforced polyphthalamide composites processed in twin-screw extruders with L/D 40:1, the addition of 0.5–3 wt% phenyl hydrogen silicone resin SH303-2B based on fiber weight is introduced through a side-stuffer downstream of the melting zone to limit residence time and prevent hydride degradation at melt temperatures above 310 °C. The treatment is applied as a 5–10 wt% solution in aromatic hydrocarbon solvent, with the fiber roving pre-dried at 120 °C for 2 h when surface moisture exceeds 0.3%. Published data for this specific resin-fiber configuration is limited; the 0.5–3 wt% window is established from production trials rather than standardized database values. The impregnated roving is dried at 150 °C and cured for 30 min to form a phenyl-silicone interphase that reduces water uptake at the glass/polymer boundary. The impregnation line must exhaust hydrogen gas released during curing at 150 °C; open flame dryers are not used. In high-voltage insulator applications, the same resin is diluted to 5 wt% solids and sprayed onto porcelain or glass substrates, then cured at 200 °C for 1 h to produce a hydrophobic surface with receding water contact angle above 90° when tested by ASTM D5946-17. Compliance for the finished insulator is assessed under IEC 62217:2012 for polymeric insulators for indoor and outdoor use with nominal voltage greater than 1,000 V and IEC 61109:2008 for composite suspension and tension insulators. Terminal finished product types include glass-fiber-reinforced polyphthalamide brackets, high-voltage composite insulator housings, porcelain bushing hydrophobic seals, and silicone rubber sheds for coastal substations.
Conformal coating thickness below 25 µm cannot mask topographical defects at solder fillets, while thickness above 75 µm prevents automated optical inspection and increases thermal resistance at power MOSFETs. SH303-2B is added to solvent-borne silicone conformal coating solids at 10–25 wt% based on total resin, providing Si-H functionality for final crosslinking and phenyl groups for hydrophobicity without introducing halogenated flame retardants. Selective spray application uses air-assisted atomization with nozzle pressure below 0.2 MPa and board preheat at 40 °C; solvent flash-off is controlled at 60 °C for 10 min, followed by thermal cure at 100 °C for 30 min. Mixed coating pot life at 25 °C is 6–8 h; viscosity doubling occurs before gelation and causes nozzle drift on selective spray heads. The cured film is inspected for fluorescence under 365 nm UV to verify edge coverage on fine-pitch connectors. Insulation resistance is tested by IPC-TM-650 Method 2.6.3.3 after 85 °C/85% RH conditioning, and volume resistivity is recorded by ASTM D257-14; the acceptance limit is above 1012 Ω. Qualification follows IPC-CC-830B and IEC 61086-2:2019 for coatings for printed board assemblies. Flux residues from no-clean solder pastes reduce surface insulation if the coating has residual silanol, so the formulation is biased toward Si-H to Si-Vi excess rather than stoichiometric balance. Terminal finished product types include engine control unit boards, outdoor LED driver circuits, power module top-coats, and automotive battery management system assemblies.
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Phenyl Hydrogen Silicone Resin SH303-2B is supplied as a phenyl-substituted organohydrogen polysiloxane liquid. The material places reactive Si–H sites within a phenyl-rich siloxane matrix, allowing platinum-catalysed hydrosilylation with vinyl-functional phenyl silicone polymers while contributing higher refractive index and thermal-oxidative resistance than unmodified methyl hydrogen fluids. It is used in addition-cure silicone encapsulants, optical bonding materials, and high-temperature elastomer formulations where dimethyl hydrogen silicone fluids produce haze, low refractive index, or insufficient thermal stability.
Batch-specific acceptance data should be obtained from the supplier certificate of analysis because phenyl distribution and hydrogen equivalent mass can shift with equilibration conditions. Generic class values should not be substituted for lot-specific limits during production qualification.
The resin is characterised by standard methods that permit comparison with other liquid siloxane crosslinkers. Table 1 provides a representative property envelope for this chemistry class. These values are not certified specification limits; the supplier CoA governs lot acceptance.
| Parameter | Test method | Typical class range |
|---|---|---|
| Appearance | Visual inspection | Colourless to pale yellow liquid |
| Viscosity at 25°C | ISO 3219 | 800–2000 mPa·s |
| Refractive index at 25°C | ASTM D1218 | 1.52–1.54 |
| Si–H content | Alkali hydrolysis gasometric titration | 0.20–0.40 wt% |
| Volatile content | ISO 3251 | <1.0% |
| Density at 25°C | ISO 2811-1 | 1.05–1.15 g/cm³ |
Viscosity is recorded at 25°C using a concentric-cylinder or cone-and-plate viscometer in accordance with ISO 3219. Refractive index is measured on a digital refractometer calibrated with a fused-silica standard under ASTM D1218. The Si–H mass fraction is determined by alkaline decomposition and volumetric hydrogen evolution, a gasometric procedure that avoids interference from phenyl proton signals that complicate direct NMR integration. Volatile content is measured by ISO 3251 under forced air at 150°C for 2 h; specimens are tared in aluminium dishes and cooled in a desiccator before reweighing.
Phenyl-to-methyl ratio is an additional control for optical and thermal behaviour. In phenyl hydrogen resins of this viscosity class, 1H NMR integration in toluene-d8 typically shows phenyl-to-methyl ratios between 0.8:1 and 1.5:1. Higher phenyl content raises refractive index and glass transition temperature but can reduce low-temperature flexibility and increase viscosity.
In hydrosilylation cure, stoichiometry is calculated from Si–H equivalents and vinyl equivalents rather than weight fractions. A molar ratio of Si–H to vinyl is maintained between 1.1:1 and 1.8:1 to offset side reactions and minor volatile loss. Ratios below 1.0:1 leave residual unreacted vinyl groups and produce a tacky surface, while ratios above 2.0:1 may liberate hydrogen during humid storage. The crosslinking reaction is followed by oscillatory rheometry on a cone-and-plate system with 25 mm diameter and 1° cone angle at 150°C; the storage modulus and loss modulus crossover is recorded as the gel point under ISO 6502 conditions.
Phenyl substituents reduce catalyst poisoning and raise network thermal resistance relative to methyl-only systems. In addition-cure LED encapsulant trials, formulations containing SH303-2B as the sole crosslinker are cured at 150°C for 60 min, followed by post-cure at 180°C for 2 h. Hardness development is measured with a Shore D durometer under ASTM D2240; typical cured networks reach 60–75 Shore D depending on the vinyl base polymer and hydrogen-to-vinyl ratio. Optical transmittance is evaluated on 10 mm thick specimens using a haze-gard instrument per ASTM D1003. Comparative published data indicate that phenyl substitution shifts the 5% mass loss temperature of cured siloxane networks by approximately 50–80°C in inert atmosphere when compared with polymethylsiloxane analogues. Published data for this specific SH303-2B configuration is limited, and batch-specific validation is required.
Storage modulus at 25°C after cure is commonly between 50 MPa and 250 MPa for optical encapsulants, but this range is controlled by the base polymer and filler loading. The phenyl hydrogen resin contributes lower crosslink shrinkage than vinyl silane crosslinkers because polysiloxane segments provide longer chain flexibility between network junctions. During cavity dispensing, precise metering is maintained with positive-displacement pumps rated for viscosities above 1000 mPa·s; diaphragm valves with perfluoroelastomer seals are preferred because phenyl silicone fluids swell nitrile wetted parts.
Formulating with this crosslinker requires attention to inhibitor concentration. Acetylene alcohol inhibitors such as 1-ethynyl-1-cyclohexanol are used at 0.02–0.08 wt% of total formulation to extend pot life. Platinum catalyst is added as a Karstedt-type complex at 2–10 ppm platinum by mass. Increasing phenyl content can slightly retard cure speed; gel time at 150°C typically increases from 20 s to 70 s as phenyl-to-methyl ratio rises within the class envelope. The effect is offset by raising platinum concentration within the stated range or by increasing cure temperature to 170°C for short-cycle transfer molding.
Substitution becomes technically justified when optical clarity, high refractive index, or thermal-oxidative resistance is a specification requirement. Polymethylhydrogen siloxanes have refractive indices near 1.40, while SH303-2B class materials lie in the 1.52–1.54 range. This difference reduces refractive index mismatch at LED chip and phosphor-silicone interfaces. In a cured clear encapsulant, the change from methyl hydrogen fluid to phenyl hydrogen resin can reduce total internal reflection loss, though the exact magnitude depends on chip architecture, surface roughness, and phosphor particle scattering; no universally applicable percentage improvement can be stated without device-level ray tracing.
Compared with low-viscosity methyl hydrogen fluids, the phenyl hydrogen resin exhibits reduced volatility and higher flash point. This permits degassing under vacuum at 10–50 mbar for 5–10 min without excessive stripper loss. Unlike low-molecular-weight silane crosslinkers, the polymeric resin is less prone to migration to the substrate interface during cure, reducing delamination and oil bleed in durable optical assemblies.
Compared with separate phenyl vinyl base polymer and MQ hydrogen resin systems, SH303-2B combines phenyl substitution and hydrogen functionality in one resin. This single-component crosslinker strategy can avoid phase separation that occurs when a high-refractive-index phenyl silicone base polymer is blended with a low-refractive-index hydrogen fluid. The result is a more uniform cured network without high-shear dispersion of incompatible hydrogen resins.
Table 2 summarises property-class differences observed when SH303-2B is used in place of common alternative crosslinkers. The values are typical class comparisons and must be confirmed on each production lot.
| Property | Methyl hydrogen fluid | Phenyl hydrogen resin SH303-2B | Observed formulation effect |
|---|---|---|---|
| Refractive index | ≈1.40 | 1.52–1.54 | Reduced index mismatch in optical encapsulants |
| Volatility | High | Low | Reduced vacuum degas loss and fewer bubbles |
| Thermal degradation resistance | Lower | Higher | Less yellowing after thermal ageing |
| Compatibility with phenyl vinyl base polymer | Limited | High | Transparent cured network without haze |
| Crosslink density | Moderate | High | Harder cured parts with lower flexibility |
Compared with phenyl vinyl silicone resins, SH303-2B contains hydrogen rather than vinyl functionality and therefore cannot serve as the primary network former. It is supplied at lower viscosity than many phenyl vinyl base polymers, which permits fine adjustment of crosslink density. Unlike MQ phenyl hydrogen resins that may require solvent dilution to achieve pourable viscosity, the product remains flowable at ambient temperature.
The resin should be stored in tightly sealed steel or fluorinated HDPE drums at temperatures below 30°C and at relative humidity below 60%. Si–H groups hydrolyse slowly in the presence of water and acidic or basic impurities, releasing hydrogen gas; containers must be vented or opened under local exhaust ventilation when moisture ingress is suspected. Bulk transfer should use stainless steel lines and positive-displacement pumps with dry nitrogen blanketing. Prolonged contact with copper, zinc, or iron acetylacetonate residues can catalyse Si–H condensation; stainless steel and glass are preferred wetted materials.
Batch-to-batch viscosity drift is typically below ±5% after 12 months when storage is maintained at 25°C and containers remain unopened. Exposure to repeated freeze-thaw cycles is not recommended because phenyl silicone resins may develop reversible turbidity below 0°C. If turbidity appears, the product should be warmed to 25°C under nitrogen and mixed with low-shear agitation before use.
The resin must not be combined with amine-based additives, organotin compounds, or sulfur-containing adhesion promoters in the uncured state because these species poison the platinum catalyst or accelerate Si–H side reactions. A compatibility test using differential scanning calorimetry under ISO 11357-1 is advised when new additives are introduced; severe incompatibility is indicated by a reduction in reaction enthalpy greater than 15% or by onset temperature broadened beyond 10°C when compared with a reference formulation.
For electronic applications, supplier documentation should be reviewed for REACH SVHC status and RoHS Directive 2011/65/EU restrictions. No authoritative public database entry for this specific product can be substituted for the supplier compliance declaration; the manufacturer retains responsibility for placing the product on the market under applicable regional chemical control laws.
For LED encapsulation, a representative formulation is prepared by weighing SH303-2B and a phenyl vinyl silicone base polymer at the required molar ratio into a planetary centrifugal mixer. The mixture is homogenised at 2000 rpm for 2 min, then degassed in a vacuum chamber at 10 mbar for 5 min. The liquid is dispensed into leadframe cavities using a piston or auger dispenser with needle inner diameter 0.3–0.8 mm. Cure is performed in a convection oven at 150°C for 60 min. Cured parts are conditioned at 23°C and 50% relative humidity for 24 h before hardness and adhesion measurements under ASTM D2240 and ASTM D4541.
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