| HS Code | 388001 |
| Product Name | Methyl Terminated Hydrogen Branched Silicone Oil RH-H23 |
| Chemical Type | Methyl-terminated hydrogen-branched polysiloxane |
| Appearance | Colorless to slightly yellow transparent liquid |
| Viscosity At 25 C | 20-50 mPa·s (typical) |
| Hydrogen Content | 0.20-0.30 wt% (typical) |
| Specific Gravity At 25 C | 0.95-0.99 |
| Refractive Index At 25 C | 1.400-1.410 |
| Flash Point | >100 °C |
| Volatile Content | ≤1.0 wt% |
| Active Content | ≥99% |
| Solubility | Soluble in toluene, xylene, hexane, and other nonpolar solvents; insoluble in water |
| Storage Conditions | Store in a dry, cool, ventilated place away from light and moisture |
| Shelf Life | 12 months in unopened original packaging |
| Reactivity | Contains Si-H groups; reacts with vinyl silicones in hydrosilylation and can release hydrogen with moisture or alkali |
As an accredited Methyl Terminated Hydrogen Branched Silicone Oil RH-H23 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 25 kg sealed steel drums, RH-H23 methyl terminated hydrogen branched silicone oil is stored in a cool, dry area. |
| Container Loading (20′ FCL) | 20′ FCL loaded with RH-H23 silicone oil in sealed drums, palletized/secured, labeled, moisture-protected, with even weight distribution. |
| Shipping | RH-H23 is typically shipped as a non-hazardous silicone oil in sealed steel drums or IBCs under cool, dry conditions, protected from moisture and contamination. Always confirm the current SDS and applicable local transport regulations before shipment. |
| Storage | Store Methyl Terminated Hydrogen Branched Silicone Oil RH-H23 in a cool, dry, well-ventilated area away from heat, sparks, flames, and strong oxidizers. Keep containers tightly closed to prevent moisture ingress and contamination. Protect from freezing and direct sunlight. Store only in original or approved, clearly labeled containers; ground and bond during transfer. Maintain good housekeeping, avoid spillage, and follow local regulations. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored cool, dry, well-ventilated, and in original sealed containers. |
Methyl terminated hydrogen branched silicone oil RH-H23 is compounded into two-part addition-cure liquid silicone rubber for medical pump diaphragms at an Si-H to vinyl molar ratio of 1.4:1 to 2.0:1. Each lot is verified by gasometric Si-H titration with a tolerance of ±0.10 mmol/g; deviation beyond ±0.15 mmol/g shifts the cured network into either an under-cured state with excessive compression set or an over-crosslinked state with reduced elongation. Karstedt platinum catalyst is dosed at 5–50 ppm Pt, and 1-ethynyl-1-cyclohexanol inhibitor at 0.02–0.08 phr maintains pot life between 24 h and 72 h at 25°C. On the injection line, two-component dosing with a static mixer is operated with barrel temperature at 25–35°C; shot volume is held within 70–85% of metering chamber capacity to avoid stagnant zones and premature gelation. Mold temperature is controlled between 170°C and 200°C, with cure time of 20–60 s/mm of wall section. Mold tolerance is ±5°C because thick sections retain reactive Si-H below the lower limit, while silica-filled surfaces scorch above the upper limit. Post-cure at 200°C for 4 h reduces volatile oligomers and consumes residual hydride. Final articles are extracted in purified water at 121°C for 1 h under USP Class VI protocols and assessed per ISO 10993-5:2009. The branched architecture creates higher network junction density than linear polymethylhydrogen siloxane at the same nominal hydride content; Shore A hardness measured by ISO 48-4:2020 rises by 5–10 points when the Si-H to vinyl ratio moves from 1.4:1 to 2.0:1. Compression set under ISO 815-1:2019 is reduced below 20% after 22 h at 175°C. The terminal product is a translucent peristaltic pump diaphragm requiring no external lubricant.
| Downstream application | Compliance anchor | Test condition | Process boundary |
|---|---|---|---|
| Medical LSR pump diaphragm | FDA 21 CFR 177.2600; USP Class VI; ISO 10993-5:2009 | Purified water extraction at 121°C for 1 h | Post-cure at 200°C for 4 h |
| Food-contact release liner | FDA 21 CFR 175.320; EC 10/2011; FINAT FTM 10/11 | Peel at 300 mm/min; specific migration limits under Annex II | Dry coat weight 0.8–1.8 g/m² |
| Power semiconductor potting gel | IEC 60068-2-14; UL 94 V-0 with ATH filler | Thermal cycling -40°C to 150°C, 500 cycles | Vacuum degas at 5–10 mbar absolute |
| Cellulose filter media hydrophobation | AATCC 22; ISO 9237 | Spray test; air permeability at 200 Pa | Add-on limit 3.0 wt% on fiber dry mass |
| Addition-cure HCR gasket | ASTM D471-16; ISO 37:2017 | IRM 903 oil at 150°C for 70 h | Residual Si-H IR absorbance at 2160 cm⁻¹ absent |
| Defoamer concentrate | ASTM E2407; REACH | Foam collapse at 0.1 wt% active solids | N₂ reactor headspace, flame arrestor vent |
Solvent-free thermal release coating formulations for PET liners use RH-H23 as the hydride donor at 3.0–6.0 parts per hundred of vinyl-functional dimethylpolysiloxane, with Karstedt platinum catalyst at 80–120 ppm Pt. The bath is coated on a five-roll coating head at 1.0–1.5 g/m² dry silicone coat weight, followed by forced-air cure at 150–180°C for 10–15 s. Since the branched Si-H fluid liberates hydrogen under basic surface contamination and moisture, the substrate is pre-dried to below 0.5% moisture by infrared heaters and the coating bath is blanketed with dry nitrogen. Release force is measured by FINAT FTM 10 at 300 mm/min peel against a standard test tape and maintained between 6 cN/25 mm and 15 cN/25 mm; subsequent adhesion retention per FINAT FTM 11 remains above 80% of the uncoated control. Coat weight tolerance is limited to ±0.2 g/m² because discontinuity occurs below 0.8 g/m² and release force collapses above 1.8 g/m². Food-contact liner compliance is anchored to FDA 21 CFR 175.320 and migration limits under EC 10/2011; residual Si-H is not detectable by attenuated total reflectance FTIR in the cured film. The terminal product is a release liner used in high-speed label converting and adhesive tape die-cutting.
For depth filter paper used in coalescing and air-oil separation, RH-H23 is applied at 1.0–2.5 wt% on dry fiber mass from an aliphatic solvent or aqueous emulsion, with 0.1–0.3 wt% dibutyltin dilaurate as hydrolysis-condensation catalyst. The Si-H groups undergo moisture-assisted hydrolysis to silanol and subsequently condense with cellulose hydroxyl sites while crosslinking into a discontinuous hydrophobic film. The impregnated web is dried at 110°C for 30 s and cured at 150°C for 3 min. Water repellency is confirmed by AATCC 22 spray rating; a rating of 80 or higher is maintained when add-on exceeds 1.5 wt%. Air permeability under ISO 9237 at 200 Pa decreases by 10–15% relative to the untreated web at 2.5 wt% add-on. Published data for this specific configuration is limited, so the upper add-on boundary is set at 3.0 wt% by plant trials because paper brittleness and pressure drop become production-limiting beyond this level. The terminal product is a hydrophobic filter layer for fuel-water separation elements.
Addition-cure silicone potting gel for power semiconductor modules is formulated with RH-H23 at an Si-H to vinyl molar ratio of 1.2:1 to 1.6:1; higher hydride excess creates dense domains that reduce low-temperature stress absorption and increase wire-bond fracture risk under thermal cycling. The filled liquid is degassed under 5–10 mbar absolute pressure after mixing because basic aluminium trihydroxide flame-retardant filler at 25–40 wt% catalyses Si-H hydrolysis and hydrogen release when processing temperature exceeds 120°C. Cure proceeds at 100°C for 30 min, followed by 150°C for 1 h. Hardness is controlled between Shore 00 30 and 50 per ASTM D2240-15; elongation at break under ISO 37:2017 remains above 100%. Thermal cycling per IEC 60068-2-14 from -40°C to 150°C for 500 cycles is used for module qualification; however, published data for RH-H23 specifically in this filled gel configuration is limited, so differential scanning calorimetry is required to verify full consumption of the hydrosilylation exotherm before lot release. The terminal product is a stress-relief encapsulant dispensed under vacuum into IGBT housings.
On a two-roll mill processing addition-cure heat-cured rubber, RH-H23 is added at 1.2–2.5 phr to a vinyl-functional gum containing 40 phr fumed silica. Mill roll temperature is maintained below 40°C because the platinum catalyst system activates above 70°C; chilled rolls prevent mill scorch during incorporation. The branched hydride fluid disperses with lower air entrainment than linear polymethylhydrogen siloxane; Brookfield viscosity at 25°C is typically 150–400 mPa·s, allowing direct addition without masterbatch dilution. Press cure at 170°C for 10 min, followed by post-cure at 200°C for 4 h, yields automotive gasket stock with tensile strength above 8 MPa and elongation at break above 400% per ISO 37:2017. Residual Si-H is monitored by infrared absorption at 2160 cm⁻¹; a measurable peak above baseline indicates incomplete cure and requires additional post-cure time. Transfer molding of this compound demands vent cleaning and controlled clamping force below 800 kN because the low-viscosity branched hydride fraction migrates to the parting line under excessive pressure and forms tacky surface layers. Oil resistance is tested by ASTM D471-16 immersion in IRM 903 oil at 150°C for 70 h; volume swell is held below 5% for under-hood gasket applications. The terminal product is a heat-resistant sealing element used in automotive air intake and cooling circuits.
When RH-H23 is used to hydrophobize fumed silica in defoamer concentrates for water-miscible metalworking fluids, the reaction is run at 3–8 parts per hundred silica in a nitrogen-purged reactor at 120–150°C for 2 h. The Si-H groups condense with surface silanol groups and evolve hydrogen; the reactor headspace is vented through a flame arrestor, and residual hydride is confirmed absent by FTIR before discharge. Treated silica is then dispersed at 5–15 wt% silica solids into a silicone-polyether carrier. Foam collapse is evaluated under ASTM E2407 at 0.1 wt% active solids in a standard agitated aqueous system; collapse time below 30 s and knockdown time below 10 s are used as in-house release criteria. Published data for this specific defoamer configuration is limited, so the batch record includes Brookfield viscosity at 25°C and silanol content of the treated silica before compounding. The terminal product is a concentrated foam-control agent for synthetic and semi-synthetic cutting fluids.
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Methyl terminated hydrogen branched silicone oil RH-H23 is a hydride-functional polysiloxane oligomer in which the terminal siloxane positions are capped with methyl groups, while reactive silicon-hydrogen bonds are located on pendant and branched-chain positions. The material is supplied as a non-emulsified, storage-stable liquid and is classified as a branched polymethylhydrosiloxane fluid rather than a linear dimethylsiloxane-methylhydrosiloxane copolymer. The branched structure introduces trifunctional or tetrafunctional siloxane nodes that increase the density of Si-H sites per molecule without producing the chain extension that raises viscosity in linear analogues. Methyl termination replaces terminal Si-H with non-reactive trimethylsilyl groups; this reduces moisture-driven chain-end condensation and lowers the concentration of terminal hydride available for premature hydrogen release. The model code RH-H23 is supplier-specific, and the exact CAS registration may vary with the distribution of mono-, di-, tri-, and tetrafunctional siloxane building blocks. For production use, the material should be transferred in closed stainless steel or glass-lined equipment under dry nitrogen. Published data for this specific configuration is limited, and lot-specific characterization is required before formulation.
Terminal methyl capping shifts reactive Si-H from chain ends to internal and branch positions. In linear methyl hydrogen silicone fluids, terminal Si-H groups can act as monofunctional chain stoppers in hydrosilylation or can hydrolyze to silanol. RH-H23 limits terminal Si-H concentration, leaving the hydride inventory available as pendant and branching groups for hydrosilylation, dehydrogenative coupling, or reduction. At equivalent weight-percent hydrogen, the branched architecture delivers more Si-H groups per molecule than a linear copolymer of similar viscosity because the branched molecule remains compact while carrying multiple functional nodes. This property is most relevant when high crosslink density is required without lowering formulation viscosity to solvent-like levels. Total Si-H content alone does not define performance; the distribution among difunctional, trifunctional, and tetrafunctional siloxane units controls steric availability and reaction kinetics. Release products in this class should be specified by viscosity at 25 °C, density, refractive index, volatile content, Si-H hydrogen, and flash point.
| Parameter | Typical range | Test method |
|---|---|---|
| Appearance | Clear liquid free of gel particles | Visual inspection |
| Viscosity at 25 °C | 15–40 mPa·s | ASTM D445-21a / ISO 3104:2023 |
| Density at 25 °C | 0.98–1.00 g/cm³ | ASTM D4052-18a / ISO 12185:1996 |
| Refractive index at 25 °C | 1.390–1.410 | ASTM D1218-12(2020) / ISO 489:1999 |
| Volatile content | ≤1.0 wt% | ISO 3251:2019 |
| Si-H hydrogen | 0.15–0.30 wt% | Titrimetric Si-H, internal method |
| Flash point | >170 °C | ASTM D92-18 / ISO 2592:2017 |
In platinum-catalyzed addition-cure networks, the branched polyhydridosiloxane acts as a crosslinker with vinyl-terminated or vinyl-pendant polysiloxanes. The practical Si-H:vinyl molar ratio is usually maintained between 1.2:1 and 2.0:1 to achieve cure completeness while limiting residual hydride. Because the branched topology preserves compact molecular volume, the formulator can raise crosslink density with less viscosity increase than with a linear hydride fluid. Mixing should be carried out under dry nitrogen, and water content in the formulation should be controlled below 100 ppm to avoid premature hydrogen evolution from Si-H hydrolysis. Pot life is governed by platinum catalyst level, inhibitor concentration, and processing temperature; no universal gel time can be assigned. Platinum concentrations of 2–10 ppm are common in addition cure, but inhibitor choice modifies pot life. For high-speed coating lines, the material must be evaluated for wetting and bubble release on the target substrate. The branched product is also used in release-coating systems where low cyclic volatile content matters; when outgassing is a specification requirement, total mass loss should be assessed under ASTM E595-15 or the relevant end-use standard.
In electronic potting, encapsulated optical components, and precision assemblies, low-molecular-weight cyclic dimethylsiloxanes can deposit on contacts or optics. Branched methyl-terminated hydride fluids are selected over some linear methyl hydrogen silicone oils because branching can reduce the population of low-ring cyclic species generated during polymer equilibration. The choice is not automatic; formulators should identify the allowed total mass loss and collected volatile condensable materials under ASTM E595-15 for the specific cure schedule. During processing, exposure to ambient humidity above 60% RH can cause gradual Si-H hydrolysis, particularly in the presence of residual platinum or tin catalyst. Vacuum mixing at 20–50 mbar absolute is recommended after catalyst addition to remove entrained hydrogen and air before dispensing. In high-voltage potting, void formation from hydrogen evolution is a failure mode; therefore, open-time after mixing should be limited, and the blend should not be held in closed containers without pressure relief.
For hydrophobic surface treatment of masonry, glass, textiles, and mineral coatings, RH-H23 is typically diluted in an aliphatic or siloxane carrier and applied by spray, dip, or padding. The fluid reacts with surface hydroxyl groups or forms a low-surface-energy network after moisture cure. Reported water contact angles for comparable branched polymethylhydrosiloxane films range from 95° to 105° after thermal cure; published data for this specific configuration is limited. Water repellency on masonry should be measured by ASTM C67/C67M-21 or the project-specific absorption standard, while textile spray rating is commonly determined by AATCC TM22-2017. The treatment level must be adjusted by porosity; dense surfaces retain less fluid and may require repeated application or a lower concentration to avoid visible film. The product is not a universal hydrophobe for all substrates; adhesion and durability under UV exposure should be tested according to the intended service environment.
In mass-pot casting or static potting, the branched hydride fluid produces a higher local Si-H concentration than a linear analogue of equal hydrogen content. This can increase exotherm if platinum catalyst is overdosed. Process control must account for inhibitor depletion and heat transfer from the bulk. At processing temperatures above 60 °C, working life shortens rapidly; many production lines hold catalyzed material at 20–30 °C before staged oven cure. Thermogravimetric data for branched hydridosiloxanes generally show decomposition onset above 250 °C under nitrogen, but actual onset is modified by residual catalyst, filler, and chain-end chemistry. The gel point in addition-cure systems is most reliably recorded by oscillatory rheometry as the crossover of storage modulus and loss modulus under ISO 6721-10:2015 or an equivalent method. Uncured RH-H23 should not be exposed to continuous temperatures above 150 °C; hydrogen loss and network rearrangement can occur before visible gelation.
Differences from other hydrogen silicone products are most visible in viscosity-functionality relationships, migration tendency, and volatile profile. Linear methyl hydrogen silicone fluids are mobile chains with Si-H distributed along the backbone; they can migrate more readily in cured matrices and may contribute to surface tack or extractable silicone. RH-H23 has a branched, methyl-terminated structure that lowers migration tendency and raises topological crosslink density when used in addition cure. Extractable silicone after cure is used as a production proxy for migration; no performance claim should be accepted without lot-specific extraction data. The same branching can reduce low-temperature flexibility if the product is used at high loading because the network becomes more rigid. Compared with fully hydrogen-terminated fluids, RH-H23 shows lower terminal Si-H concentration and reduced moisture-induced condensation at chain ends. Direct substitution of RH-H23 for a linear hydride fluid is not recommended without rebalancing Si-H:vinyl ratio, inhibitor level, and mixing time. For release coatings, the branched product may reduce extractables after cure, but published data for this specific configuration is limited. The product must not be combined with amine-functional additives, primary or secondary alcohols in the presence of metal catalysts, or strong bases because Si-H dehydrogenation or hydrolysis can generate hydrogen gas.
| Parameter | RH-H23 branched methyl-terminated | Linear methyl hydrogen silicone fluid | Hydrogen-terminated silicone fluid |
|---|---|---|---|
| Terminal group | Trimethylsilyl | Trimethylsilyl or methyl | Dimethylhydrosilyl |
| Si-H location | Pendant and branch nodes | Pendant along chain | Terminal and pendant |
| Volatile low-ring cyclics | Lower at equivalent viscosity | Higher without stripping | Moderate |
| Migration tendency in cured matrix | Lower | Higher | Moderate to high |
| Crosslink density at equal Si-H:vinyl | Higher topological density | Moderate | Lower chain-end network |
| Typical Si-H content | 0.15–0.30 wt% | 0.10–1.50 wt% | 0.10–0.80 wt% |
| Viscosity at 25 °C | 15–40 mPa·s | 5–100 mPa·s | 5–50 mPa·s |
For release coatings, the branched hydride fluid can be formulated with vinyl-functional silicones and a platinum catalyst in solventless, solvent, or emulsion systems. The coating bath viscosity and coat weight are controlled by line speed and transfer roll geometry. The cure response is monitored by retained silicone extractables; extraction with methyl isobutyl ketone or toluene followed by gravimetric determination is typical in production. Because RH-H23 introduces branch points, the cured network may show higher modulus and lower elongation than a comparable linear-hydride formulation; if flexible release is required, the formulator must rebalance the vinyl polymer chain length and the hydride level. No single addition level can be specified for all release values; the release force should be measured by FINAT FTM 3 or TLMI L-IA-10 after aging at 70 °C.
Replacement of a linear methyl hydrogen silicone fluid with RH-H23 changes the shear history required for uniform incorporation. The branched product may require longer low-shear mixing to wet high-surface-area fillers such as fumed silica; however, high-shear rotor-stator mixing above 15 m/s tip speed should be avoided when volatile siloxane loss or cavitation is a concern. A slow-sweep planetary mixer with a vacuum dome is preferable for filled formulations because it permits degassing without excessive shear. Viscosity should be measured before and after compounding to detect moisture uptake or premature gelation. Closed-loop production equipment should be nitrogen-blanketed at 50–100 mbar positive pressure, and storage tanks should be fitted with 5A molecular-sieve breather vents. For continuous dosing, progressive cavity pumps with tungsten carbide stators are preferred over air-entraining diaphragm pumps. The fluid’s flash point above 170 °C reduces normal ambient vapor ignition risk, but local exhaust ventilation is still required because low-level volatile siloxanes can condense on nearby surfaces.
Regulatory documentation for RH-H23 should include REACH registration status, GHS classification, and applicable TSCA inventory status. The material is not automatically compliant with food-contact or medical-grade requirements; formulators must verify specific migration limits under EU 10/2011 or FDA 21 CFR 175.300 where relevant. The product is silicone-based and should not be incinerated with alkali metal salts, because silica fume and hydrogen by-products can form. Uncured fluid should be disposed of according to local hazardous waste regulations; cured residues are usually non-hazardous. Storage stability is influenced by moisture exclusion and temperature; sealed containers should be stored below 40 °C and consumed within the supplier-specified shelf life. If a container is opened in humid air, the remaining contents should be purged with dry nitrogen before resealing, and any pressure build-up from hydrogen evolution should be relieved cautiously.
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