| HS Code | 904772 |
| Appearance | Colorless to light yellow transparent liquid |
| Viscosityat25c | 20 mm²/s |
| Densityat25c | 0.98 g/cm³ |
| Refractiveindexat25c | 1.397 |
| Hydrogencontent | 1.5% |
| Flashpoint | >100 °C |
| Volatilematter | ≤2% at 150 °C for 3 h |
| Watercontent | ≤0.1% |
| Ph | 6–7 |
| Surfacetension | 20–21 mN/m |
| Solubility | Soluble in organic solvents; insoluble in water |
| Thermalstability | Stable under normal storage conditions |
As an accredited Methyl Hydrogen Silicone Oil RH202-20 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Methyl Hydrogen Silicone Oil RH202-20 is packaged in 25 kg polyethylene-lined steel drums, clearly labeled and sealed for safe transport. |
| Container Loading (20′ FCL) | Methyl Hydrogen Silicone Oil RH202-20, suitably packed and loaded into a 20′ FCL container for ocean shipment. |
| Shipping | Methyl Hydrogen Silicone Oil RH202-20 is shipped as a liquid in sealed, labeled, UN-approved containers. Transport away from moisture, heat, and ignition sources. Confirm hazard classification, packing group, and shipping name against the current SDS and local regulations before dispatch. |
| Storage | Store Methyl Hydrogen Silicone Oil RH202-20 in a cool, dry, well-ventilated warehouse, away from heat, ignition sources, and direct sunlight. Keep containers tightly closed and clearly labeled. Separate from oxidizing agents, acids, alkalis, and moisture. Use original containers and avoid damage or leakage. Maintain good ventilation and follow local fire and chemical-storage regulations. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored unopened in the original container under recommended conditions. |
On solventless thermal addition-cure release coating lines running glassine, densified kraft, and PET release liners, methyl hydrogen silicone oil RH202-20 is introduced as the Si-H functional crosslinker responding to a vinyl-functional polydimethylsiloxane terpolymer. Formulation control on multi-roll coaters is set around a Si-H:Si-Vi molar ratio of 1.2:1 to 1.8:1; below 1.1:1, the cured film retains unreacted vinyl groups and fails smear tests under FINAT FTM 2, while above 2.0:1, residual Si-H undergoes slow air oxidation and generates a post-cure release-force drift of up to 30–50% in 7-day aging at 40°C. The product is metered at 2.5–6.0 wt% relative to total silicone solids, with platinum catalyst levels held at 50–120 ppm Pt depending on line speed and web temperature. On production-scale five-roll solventless coating heads operating at 300–600 m/min, the limiting parameter is the viscosity gap between the Si-H crosslinker and the higher-viscosity vinyl polymer; if the crosslinker is fed directly into the metering nip without pre-blending, low-viscosity fluid can be worked into the rubber backing roll and create release-force striping. Typical thermal cure is delivered in a 10–15 s dwell at web surface temperatures of 120–180°C; below 120°C, hydrosilylation remains incomplete on fast lines, while above 180°C, platinum catalyst aging and edge smoke are observed. For food-contact release liners, the cured formulation is assessed under FDA 21 CFR 176.170 and EU Regulation 1935/2004/EC, with overall migration testing conducted according to EN 1186-1:2002 and organoleptic evaluation according to EN 1230-1. Terminal finished product types include release liners for pressure-sensitive adhesive labels, cast adhesive tape carriers, hygiene-strip release papers, and peel-off lids for polypropylene cups. Process water must be excluded from storage and transfer lines because hydrolysis of Si-H evolves hydrogen; at headspace concentrations above the 4 vol% lower explosive limit, forced venting is required.
Pad-bath stability in textile hydrophobic finishing with methyl hydrogen silicone oil RH202-20 depends less on initial bath clarity than on hydrolysis control at the emulsion interface. In a pad-dry-cure formulation, the product is combined with a low-molecular-weight hydroxyl-terminated polydimethylsiloxane and a tin or zinc carboxylate catalyst; the RH202-20 addition is 5–20 g/L active in the pad bath, while total silicone oil emulsion is typically 20–50 g/L. The bath pH is held at 4.5–6.0 using acetic acid or citric acid; above 7.5, Si-H hydrolyzes rapidly, leading to hydrogen generation and loss of crosslink density after curing. Fabric is processed through a padding mangle set to 70–80% wet pickup at 0.2–0.4 MPa roller pressure, then dried on a stenter frame at 100–120°C for 45–90 s, followed by a cure zone at 150–170°C for 60–180 s. In recycled bath water carrying anionic dye-fixing agents, emulsion creaming accelerates, and the resulting spray rating under ISO 4920:2012 can fall from 4 to 2 after 10 home-laundering cycles under ISO 6330:2012 procedure 6N. Compliance for apparel and technical nonwovens is evaluated under Oeko-Tex Standard 100 Annex 4 and, for brands aligned with detox campaigns, against the ZDHC MRSL v3.1 limits for cyclic siloxanes and tin catalysts. The finish is classified as a non-fluorinated durable water repellent system and is specified for down-proof outerwear, tent panels, automotive interior nonwovens, and medical barrier fabrics where blood-repellence is not claimed.
For exterior masonry hydrophobation, methyl hydrogen silicone oil RH202-20 is formulated as a penetrating siloxane impregnant in aliphatic hydrocarbon solvent or as a stabilized water emulsion. The active content in a solventborne facade impregnating fluid is 5–15 wt%; water-emulsifiable grades are usually supplied at 10–20 wt% active and are diluted on site to 3–8 wt%. Application is performed by low-pressure spray at 0.2–0.4 MPa or by brush and roller at a consumption of 0.2–0.5 L/m² on cast concrete, with lower consumption on dense precast concrete and higher consumption on porous clay brick. The substrate must be at least 28 days old and have a surface moisture content below 4 wt%; otherwise, alkaline pore water hydrolyzes the Si-H group, releasing hydrogen and leaving a patchy water absorption profile. The cured hydrophobic layer is assessed by water absorption reduction and water penetration resistance under EN 13580:2002 and ASTM E514/E514M-20, and the product class is specified under EN 1504-2:2004 as a hydrophobic impregnation surface protection system. Production sites use the same fluid for concrete bridge piers, precast facade panels, exposed clay brick parapets, and historic masonry where film-forming coatings are prohibited. Visible water beading is not accepted as sole proof of protection; the relevant criterion is the capillary water absorption coefficient after 24 h immersion under the cited standards.
In injection-molded liquid silicone rubber, methyl hydrogen silicone oil RH202-20 functions as the hydrosilylation crosslinker in a platinum-catalyzed addition-cure system. The formulator sets the addition of RH202-20 at 4–12 phr relative to the vinyl-functional base polymer, corresponding to a molar Si-H:Si-Vi ratio of 1.2:1 to 1.8:1. The lower boundary is fixed by the need to consume vinyl groups during the cure cycle; at 1.1:1, compression set after 22 h at 175°C under ASTM D395-18 Method B becomes unstable across cavities, with high-cavity-number tools showing greater variability than single-cavity tools due to thermal lag. The upper boundary is fixed by post-cure surface tack and extractables: above 2.0:1, excess Si-H remains in the network and leads to detectable silicone extractables under ISO 10993-12:2021 when the part is used in medical device applications. In production molding, the two-component mixture is cooled to 18–25°C in the barrel and static mixer to prevent premature gelation, then injected into a mold held at 110–160°C; cure time is typically 5–30 s per millimetre of wall thickness, with full-cure validation by ISO 37:2017 tensile and ASTM D2240-15 Shore A hardness measurements. Metal-mold release compounds containing sulfur, amines, or phosphorus inhibit the platinum catalyst and produce localized uncured zones at the part surface, a failure mode that is observed before bulk crosslink because the inhibition front is diffusion-limited. Medical and food-contact grades are specified under FDA 21 CFR 177.2600, USP Class VI, and ISO 10993-5:2009 cytotoxicity testing, with additional compliance to ISO 10993-10:2013 for skin sensitization where the part contacts intact skin. Terminal finished product types include peristaltic pump tubes, catheter seals, dispensing valve diaphragms, baby-bottle teats, and automotive connector gaskets.
Methyl hydrogen silicone oil RH202-20 enters defoamer compounding as the reactive hydrophobizing component for fumed silica in silicone-based antifoam concentrates. The addition is 2–10 wt% of the silicone defoamer compound, depending on silica surface area and silanol density; a typical charge for a fumed silica with 200–300 m²/g BET surface area is 4–6 wt%. The mixture is processed in a jacketed vacuum disperser equipped with a Cowles blade at tip speeds of 10–25 m/s, held at 60–100°C for 30–60 min, and is periodically vented to release hydrogen generated by the reaction of Si-H with surface silanol groups and residual moisture. If the reactor is not inerted or vented, the hydrogen concentration can accumulate in the headspace and must be maintained below 4 vol% lower explosive limit. The resulting hydrophobic silica dispersion is then emulsified or compounded into mineral oil, polyether, or vegetable oil carriers to produce an antifoam with active silicone content of 10–30 wt%. For pulp and paper mill wet-end antifoams, the formulation is evaluated under FDA 21 CFR 176.200; for direct food processing operations such as sugar beet washing and fermentation, the active silicone content is assessed under FDA 21 CFR 173.340. Terminal finished product types include water-dilutable antifoam emulsions for paper machines, concentrated silicone pastes for bioethanol distillation, and pumpable antifoam blends for chemical wastewater treatment where silicones are permitted.
The treatment of precipitated alumina trihydrate and magnesium dihydroxide with methyl hydrogen silicone oil RH202-20 is carried out in heated plowshare or Henschel high-speed mixers to render the filler surface hydrophobic and reduce compound viscosity in halogen-free flame-retardant cable jackets. The addition is 0.3–1.2 wt% on filler mass for filler with specific surface area of 5–15 m²/g; higher-surface-area fillers may require up to 2.0 wt%, but overdosing leaves free Si-H in the compound and contributes to porosity during extrusion. The mixer wall temperature is maintained at 90–130°C and rotor tip speed at 15–30 m/s, with a residence time of 20–60 min. Published data for this specific configuration with RH202-20 is limited; the operational window is therefore bracketed by capillary moisture balance and by torque rise in the mixer rather than by fixed kinetic constants. Because filler surface moisture initiates Si-H hydrolysis, the mixer headspace is continuously vented and the hydrogen concentration is monitored to remain below 4 vol% LEL; a common production control is to pre-dry the filler to 0.1 wt% moisture or less before silicone injection. The treated filler is compounded into ethylene-vinyl acetate or polyethylene at 60–65 wt% loading, and the finished cable compounds are tested under IEC 60754-1 for halogen acid gas, IEC 60332-1-2 for vertical flame propagation, and RoHS Directive 2011/65/EU for restricted substances. Terminal finished product types include halogen-free flame-retardant sheathing for building wire, ropeway cable jackets, and heat-shrink tubing for electrical insulation.
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Designation RH202-20 identifies a linear methyl hydrogen silicone fluid composed primarily of poly(methylhydrosiloxane-co-dimethylsiloxane) with trimethylsilyl terminal groups. The reactive silicon-hydrogen bond is distributed along the siloxane backbone and is the basis of hydrosilylation, hydrophobing, and hydrogen-release behaviour. In the model code, 20 is associated with a nominal kinematic viscosity of 20 mm²/s at 25 °C; batch-release values generally fall between 15 mm²/s and 30 mm²/s under ISO 3104. Silicon-bonded hydrogen content for this grade is commonly reported as 0.15–0.25 wt% by iodometric titration. RH202-20 is used as a reactive intermediate, crosslinker, or surface modifier, not as a lubricating dimethyl fluid.
Batch release documentation for RH202-20 typically reports appearance, kinematic viscosity, hydrogen content, density, refractive index, and volatile content. The values below are representative of a mid-range 20 mm²/s methyl hydrogen silicone fluid; the supplier’s batch certificate should be used for lot acceptance. Sampling should follow ISO 15528 for liquid coating materials, and moisture exposure during sampling must be excluded because prolonged contact with ambient air above 60% RH can depress measured hydrogen content and generate hydrogen bubbles.
| Property | Test method | Typical range |
|---|---|---|
| Appearance | Visual | Colourless transparent liquid |
| Kinematic viscosity at 25 °C | ISO 3104 | 15–30 mm²/s |
| Hydrogen content | Iodometric titration | 0.15–0.25 wt% |
| Density at 25 °C | ISO 2811 | 0.98–1.00 g/cm³ |
| Refractive index nD25 | ASTM D1218 | 1.395–1.405 |
| Volatile content | ISO 3251 | ≤1.0% |
Hydrogen content is the critical release parameter because the molar Si-H concentration controls stoichiometry in hydrosilylation. For 0.20 wt% hydrogen, the calculated Si-H concentration is 1.98 mmol/g; this value is used to set the SiH:vinyl molar ratio. Viscosity is measured at 25 °C in a glass capillary viscometer; temperature control must be within ±0.02 °C to meet ISO 3104 repeatability. Density is reported at 25 °C by oscillating U-tube or pycnometer under ISO 2811. Refractive index is used as a rapid lot-to-lot identity check. No single ISO method exists for Si-H titration; the iodometric procedure is the standard industrial reference because it measures silicon-bonded hydrogen selectively after alkaline hydrolysis, typically with an absolute precision of ±0.02 wt%.
In textile hydrophobing operations, RH202-20 is emulsified at 20–40 wt% active content using nonionic alcohol ethoxylates and a high-shear disperser operating at 3000 rpm to a median droplet size below 2 µm measured by ISO 22412 dynamic light scattering. The emulsion is pH-adjusted to 5.0–6.0 with acetic acid because alkaline conditions accelerate Si-H hydrolysis. On a commercial pad-dry-cure range with pickup of 60–70% on woven cotton, silicone add-on is 0.5–1.5 wt% based on fibre mass; curing at 150–170 °C for 60–90 s is used. The Si-H groups react with adsorbed water and hydroxyl sites to form siloxane bridges, moving the spray rating from an untreated 0 to 90–100 under AATCC TM 22. Durability is assessed after 10–20 home-laundering cycles under ISO 6330; the finish may require an external thermofixing step above 160 °C to prevent excessive loss. Emulsion stability is checked by centrifuge at 3000 rpm for 30 min; creaming below 5% is considered acceptable. Plant trials with unstable emulsions produced silicone spots on dried fabric when pH drifted above 7.5, traced to residual alkali from scouring.
Replacing RH202-20 with a higher-hydrogen methyl hydrogen silicone fluid at equal mass addition changes the crosslink density and rheological profile of addition-cure silicones. The crosslinker demand can be calculated from the relationship m = (Rv × Vv) / HSiH, where m is crosslinker mass fraction, Rv is the target SiH:vinyl molar ratio, Vv is vinyl content in moles per gram, and HSiH is active hydrogen concentration in moles per gram. For a base polymer with vinyl content 0.10 mmol/g and a target SiH:vinyl ratio of 1.2:1, the theoretical demand for RH202-20 at 0.20 wt% Si-H is 6.1 phr. If a higher-hydrogen fluid at 0.35 wt% Si-H is substituted at the same 6.1 phr, the SiH:vinyl ratio approaches 2.1:1. The increase can raise hardness from 40 Shore A to 55–60 Shore A, lower elongation at break from 250% to 100–140%, and increase storage modulus G′ at 1 Hz by a factor of 2–4. Cure kinetics should be re-characterised by moving-die rheometry under ISO 6502 or ASTM D5289; scorch time ts1 and optimum cure time t90 are not interchangeable across Si-H concentrations.
On a 40:1 L/D twin-screw extruder running at 150–200 rpm, premature gel formation can occur when the SiH:vinyl ratio exceeds 3:1 and barrel temperature exceeds 120 °C. Reaction exotherm can be measured by differential scanning calorimetry under ISO 11357-1; in platinum-catalysed systems, cure onset typically occurs between 80 °C and 110 °C when an inhibitor is present. A production-scale batch-to-batch hydrogen content variation of ±0.02 wt% changes the theoretical crosslinker demand by roughly 10% relative; gravimetric dosing systems should therefore be recalibrated for each new lot. At the reverse boundary, a SiH:vinyl ratio below 0.8:1 can leave unsaturated vinyl sites and produce a tacky or undercured surface. Published data for this exact product in extruded addition-cure compounds is limited; the comparative ranges above are drawn from analogous low-hydrogen silicone fluids rather than a statistically controlled data set.
Release coating formulations based on solventless vinyl-functional polydimethylsiloxanes use RH202-20 as the hydride donor. At a bath viscosity of 200–400 mPa·s measured by ISO 3219, five-roll offset coating equipment applies a coat weight of 0.5–1.0 g/m²; oven dwell times of 8–15 s at 150–180 °C are typical. Release force against an acrylic test tape is measured by FINAT FTM 3 or ASTM D3330 at 300 mm/min; low-hydrogen silicone networks of this type usually fall in the 10–30 cN/50 mm range. The low Si-H density reduces post-cure release drift because fewer unreacted silicon hydride sites remain available for oxidation. Platinum catalyst levels of 50–100 ppm Pt are common; catalyst poisons such as amines, sulfur compounds, and tin soaps must be excluded. Food-contact status is not conferred by RH202-20 alone; finished coatings require assessment under 21 CFR 175.300 or EU 1935/2004.
In polyether-modified silicone surfactant synthesis, RH202-20 is hydrosilylated with allyl-terminated polyether at 80–110 °C under a 2–5 ppm Pt Karstedt catalyst. The low hydrogen content limits grafting density and reduces the risk of crosslinked gel particles. A reactor with pitched-blade turbine agitation at 200–400 rpm and nitrogen sparge is used. End-point is confirmed by disappearance of the Si-H infrared band at 2160 cm⁻¹; residual Si-H should be below 0.02 wt% before water exposure. Published data for RH202-20 specifically as a direct polyurethane foam stabilizer is limited; its function is primarily as a synthetic intermediate.
In comparison with trimethylsilyl-terminated polydimethylsiloxane fluids of similar viscosity, RH202-20 contains silicon-bonded hydrogen that exhibits an infrared absorption at 2160 cm⁻¹. Dimethyl fluids are non-reactive lubricants or release agents; RH202-20 acts as a crosslinker or surface modifier. Against methyl hydrogen silicone oils with hydrogen content above 0.75 wt%, RH202-20 generates less hydrogen on hydrolysis and produces lower crosslink density in hydrosilylation. This difference is relevant in soft elastomer and low-release coatings where excessive Si-H creates brittle films and post-cure release increase. RH202-20 also differs from vinyl-functional silicone fluids because it participates as the hydride donor in platinum-catalysed hydrosilylation, not as the unsaturated base polymer. Compared with alkoxysilanes, RH202-20 does not require moisture-cure condensation catalysts but is more sensitive to water and must be processed under dry gas. The lower active-hydrogen content also reduces hydrogen gas evolution during storage and emulsification relative to high-hydrogen fluids.
Bulk storage of RH202-20 requires sealed carbon steel or high-density polyethylene containers under dry nitrogen pad pressure of 0.1–0.3 bar. Open handling at relative humidity above 60% RH is discouraged because Si-H hydrolysis liberates hydrogen; equipment must be explosion-proof and fitted with local exhaust ventilation. The fluid is incompatible with strong bases, alkali-metal hydroxides, amines, and tin soaps, which can catalyse Si-H disproportionation or condensation. Formulations containing platinum catalyst should also be protected from sulfur-containing additives. High-temperature ovens above 180 °C require verification of volatile content to prevent film defects and excessive gas evolution. A previous batch should not be mixed with fresh material in the same storage vessel without verifying hydrogen content; segregation by lot is preferred.
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