| HS Code | 304930 |
| Productname | Volatile Silicone Fluids RH-C229 |
| Chemicalname | Decamethylcyclopentasiloxane |
| Inci Name | Cyclopentasiloxane |
| Cas Number | 541-02-6 |
| Einecs Number | 208-764-9 |
| Molecular Formula | C10H30O5Si5 |
| Molecular Weight | 370.77 g/mol |
| Appearance | Colorless transparent liquid |
| Odor | Odorless |
| Boiling Point | Approximately 210 °C |
| Density | Approximately 0.959 g/cm³ at 25 °C |
| Viscosity | Approximately 4.6 cSt at 25 °C |
| Refractive Index | Approximately 1.396 at 20 °C |
| Flash Point | Approximately 77 °C |
| Water Solubility | Insoluble |
| Volatility | High volatility |
As an accredited Volatile Silicone Fluids RH-C229 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 25 L high-density polyethylene containers, securely sealed and labeled for safe transport and storage. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Volatile Silicone Fluids RH-C229 in sealed packaging, properly secured, labeled, and documented for safe transport. |
| Shipping | Volatile Silicone Fluids RH-C229 is shipped in sealed, labeled drums or IBCs under ambient conditions, protected from heat, moisture, and ignition sources. Follow the SDS and applicable DOT/IMDG/IATA rules; classification may vary, so confirm hazardous/non-hazardous status before transport. Use compatible packaging, secure stowage, and include the SDS and emergency contact with the shipment. |
| Storage | Store in a cool, dry, well-ventilated area away from heat, sparks, flames, and strong oxidizing agents. Keep containers tightly closed when not in use and protect from direct sunlight and moisture. Maintain within manufacturer-recommended temperature limits, use secondary containment, label containers clearly, and follow local regulations and the product SDS. |
| Shelf Life | Volatile Silicone Fluids RH-C229: shelf life is typically 24 months from manufacture when kept in original, unopened packaging under recommended storage conditions. |
In anhydrous antiperspirant suspension systems, the primary function of RH-C229 is reduction of organic-phase surface tension to 18.0–21.5 mN/m as determined by ASTM D1331-14. The fluid is blended into an oil phase containing aluminium zirconium tetrachlorohydrate or aluminium chlorohydrate powders with median particle diameters from 1 µm to 15 µm, where the low surface tension permits wetting of high-surface-energy active particles and reduces tack of the cast residue. Typical anhydrous stick and roll-on matrices carry 15–40 wt% RH-C229, 12–20 wt% antiperspirant active, 1.5–3.0 wt% quaternium-18 hectorite or disteardimonium hectorite suspension gellant, and 5–15 wt% emollient esters. Aerosol antiperspirant concentrates may carry 50–70 wt% propellant A-46 after the liquid phase is filled into aluminium or tinplate cans, with the volatile silicone fraction controlling both the spray particle size and the evaporation time on skin. Processing is performed in a closed rotor-stator homogenizer at 5,000–10,000 rpm under −0.08 MPa vacuum while maintaining the batch temperature at 25–40 °C. Because moisture ingress above 0.1 wt% initiates hydrolysis of aluminium zirconium salts and can release chloride species that corrode unlined aluminium cans, the volatile silicone carrier must be stored under nitrogen or dry-air blanket and pre-checked for water content by Karl Fischer titration.
The finished formulation is filled under vacuum into aerosol cans at 20–25 °C, and the vapor tap valve orifice is selected in the range 0.016–0.023 inch to maintain a spray rate of 0.8–1.2 g/s at 40–60 psig can pressure. Leave-on antiperspirant products in the EU are governed by Regulation (EC) No 1223/2009, and the aluminium zirconium chloride hydroxide complex is restricted under Annex III; if RH-C229 is supplied as a cyclopentasiloxane-dominant fluid, Annex XVII Entry 70 of REACH applies only to wash-off cosmetics at a limit of 0.1 wt%, not to leave-on antiperspirant formats. However, distribution into markets where the product may be promoted as a body mist or shower product triggers the wash-off restriction, and the formulator must maintain a finished-product D5 content below the regulatory threshold or reformulate with a restricted-free volatile carrier.
A recurring production observation in high-pressure polyurethane foam molding for automotive seating is that reducing the volatile silicone fraction in external mold release blends below 4.0 wt% produces uneven coverage on aluminum tooling and increases the frequency of manual mold cleaning. RH-C229 is therefore maintained at 10–25 wt% of the release blend to reduce atomization viscosity and allow air-assisted spray nozzles to produce a droplet size distribution of 10–40 µm at 0.35–0.60 MPa delivery pressure. The blend is prepared in a jacketed vessel at 50–60 °C with low-shear propeller agitation until the paraffin wax phase is completely dissolved, then filtered through a 25 µm cartridge before loading into the spray skid. Mold surface temperature is controlled at 55–70 °C and the flash-off period before pouring is 10–20 s. If RH-C229 is used as a release agent component for incidental food-contact molded articles, compliance evaluation under 21 CFR 175.300 for resinous and polymeric coatings may be required in the US market, and EU Regulation 10/2011 overall migration testing at 10 mg/dm² is applicable for plastic food-contact materials. Typical finished products include flexible molded polyurethane foam cushions, steering wheel skins, and acoustic foam pads. Published data for the exact pull-off release force achievable with RH-C229 in a given mold geometry is limited; however, production experience indicates that mold release failure is more closely associated with wax crystallization in the flash-off window and uneven spray coverage than with the intrinsic surface tension of the volatile silicone fraction.
Surface tension values below 21 mN/m allow RH-C229 to function as a volatile carrier in solvent-diluted silicone conformal coatings applied to printed circuit assemblies where low-standoff ball grid array penetration is required. The fluid exhibits a kinematic viscosity in the range of 4–6 mm²/s at 25 °C measured by ASTM D445, which permits thin-film wetting without excessive solvent entrapment. In selective coating equipment, the mixture is delivered via a progressive cavity pump to an air-atomizing spray head at 0.15–0.30 MPa fluid pressure, with a board temperature of 30–50 °C and a flash-off tunnel operating at 60–80 °C for 5–10 min after coating. The cured film thickness is controlled between 25 µm and 75 µm for vibration-resistant environmental protection. RH-C229 is not formulated as an aggressive polar flux remover; its use in precision cleaning is restricted to the removal of nonpolar silicone or hydrocarbon oil films and to drying after aqueous cleaning, and it must not replace saponifier-based cleaners for rosin flux residues. For aerospace and automotive electronic assemblies, pre-coating ionic cleanliness is verified according to IPC J-STD-001H section 4.5.2, with a typical acceptance criterion below 1.56 µg NaCl eq/cm². Surface insulation resistance after coating is monitored by IPC-TM-650 2.6.3.7 under 85 °C/85% RH bias conditions, and the cured dielectric film is tested for surface resistivity by ASTM D257-14. Finished end products include engine control module boards, LED driver modules, and high-density power steering controllers.
| Control parameter | Standard or method | Typical acceptance criterion |
|---|---|---|
| Ionic cleanliness before coating | IPC J-STD-001H 4.5.2 | Below 1.56 µg NaCl eq/cm² |
| Surface insulation resistance | IPC-TM-650 2.6.3.7 | No electrochemical migration; resistance not to fall below 100 MΩ during 168 h at 85 °C/85% RH |
| Surface resistivity of cured film | ASTM D257-14 | Not less than 1.0 × 10^12 Ω/sq |
Post-addition of 0.05–0.30 wt% RH-C229 to a solventborne acrylic-melamine bake system lowers the dynamic surface tension of the liquid film sufficiently to eliminate solvent-popping craters in spray-applied automotive refinish basecoats and nitrocellulose wood lacquers. The material is introduced after pigment dispersion and before final viscosity adjustment, using a high-shear disperser at 2,000–3,000 rpm for 5–10 min without exceeding a batch temperature of 40 °C. Addition levels above 0.5 wt% on total formula create a persistent surface monolayer that can reduce recoat adhesion and cause crosshatch failures of ASTM D3359-17 to drop from 5B to 3B or lower on steel panels. The cured coating film is assessed for specular gloss using ISO 2813 and for abrasion resistance using ASTM D4060 with CS-17 wheels. In an OEM automotive basecoat line, the bake window is 140–150 °C for 20 min, during which the volatile silicone evaporates and leaves only trace siloxane at the air-coating interface. This application requires that RH-C229 be pre-diluted in the main letdown solvent before addition because direct dosing into high-viscosity millbase creates local surface tension gradients and increases the risk of seed formation. The relevant compliance framework for automotive refinish systems includes REACH substance registration for the finished coating and, for exported automotive components, screening against the Global Automotive Declarable Substance List. Finished products include solventborne basecoats, clearcoats for automotive refinish, and industrial wood lacquers. Published data for the exact dynamic surface tension reduction in every acrylic-melamine variant is limited, but the crater-suppression effect is measurable with a tensiometer according to ASTM D1331-14 in the letdown phase.
Aerosol tire dressing lines that replace aromatic hydrocarbon carriers with RH-C229 must rebalance the evaporation rate and the concentration of amino-functional polydimethylsiloxane film former because the silicone fluid has a narrower solvency window for oxidized tire waxes. The concentrate is built at 25–30 °C with 5–15 wt% RH-C229 as the volatile carrier, 10–25 wt% high-viscosity amino silicone, 1–3 wt% polydimethylsiloxane gloss modifier, and a hydrocarbon propellant blend at 60–75 wt%. The mix is charged into tinplate aerosol containers at 0.4 MPa equilibrium pressure, and the valve vapor tap diameter is set between 0.016 inch and 0.023 inch to deliver a uniform fan pattern over tire sidewalls. Because RH-C229 evaporates faster than trimethylbenzene but slower than isoparaffinic solvents, the wet film dwell time can be adjusted between 20 s and 60 s before wiping, which controls the depth of the silicone film. On a conveyorized automotive accessory filling line, the limiting factor is the slow evaporation of the silicone carrier from the aerosol concentrate; inline viscosity checks are performed at 25 °C using a Brookfield viscometer according to ISO 2555 or ASTM D2196, with a target concentrate viscosity below 1,500 mPa·s. Finished products include aerosol tire shine, exterior rubber trim dressings, and engine bay detail sprays. Compliance for automotive interior and exterior care chemicals in the EU requires substance screening under REACH and, for parts supplied to vehicle manufacturers, reporting against the Global Automotive Declarable Substance List. The key formulation boundary is that RH-C229 does not dissolve heavily oxidized rubber wax at ambient temperature; aromatic hydrocarbons are required in the cleaner phase if heavy silicone-free tire bloom must be removed before dressing.
Narrow-width nylon 6,6 webbing and polyester seatbelt edge tapes coated with solvent-based durable water repellent finishes use RH-C229 as a water-free carrier for silicone hydrophobes and fluorocarbon resins before the pad-dry-cure stage. The carrier reduces pad bath surface tension to 18–20 mN/m, enabling uniform coverage of the fiber surface during a dip-nip process with a pad pressure of 0.2–0.4 MPa and a wet pick-up of 30–50% on fabric weight. In a typical formulation, 10–20 wt% RH-C229 is combined with 5–10 wt% amino-functional silicone oil, 2–5 wt% fluorinated acrylate polymer, and an aliphatic solvent balance. The crucial operation limit is that moisture in the finishing plant must remain below 80% RH, and free water in the solvent bath must be kept below 0.1 wt%, because water ingress destabilizes the siloxane polymer film and produces uneven hydrophobic stripes along the webbing. Curing is conducted at 150–170 °C for 30–60 s in a stenter or belt oven, after which the treated fabric is tested for water repellency by AATCC 22 and for hydrostatic resistance by ISO 811 or AATCC 127. A drop in spray rating from 90 to 70 after 5 launderings generally indicates that the amino silicone crosslinker was not sufficiently cured or that the volatile carrier was not fully evaporated before heating. Finished products include automotive safety belts, military webbing, outdoor backpacks, and abrasive-resistant narrowing tapes. The compliance framework for textile auxiliaries includes OEKO-TEX Standard 100 limit values and, for manufacturing process chemicals, conformance to ZDHC MRSL where applicable. The use of RH-C229 as a solvent carrier requires that fabric off-gas monitoring be conducted after the oven to avoid residual siloxane deposition on drying frames and downstream heat-setting equipment.
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Volatile Silicone Fluids RH-C229 is a narrow-cut volatile methylsiloxane blend supplied as a clear liquid for use as a temporary carrier, mold release diluent, electronic cleaning fluid, and surface tension depressant in solvent-borne coating operations. The manufacturer’s current engineering documentation describes RH-C229 as having a lot-specific kinematic viscosity at 25 °C in the range of 2.0–4.0 mm²/s, a closed-cup flash point not lower than 55 °C by ASTM D56-22, and nonvolatile residue after 150 °C forced-air evaporation controlled to ≤0.10 wt% on the corresponding certificate of analysis. Independent peer-reviewed data for the specific RH-C229 designation is limited; these values are engineering screening parameters and not batch guarantees. Lot release documentation retained under ISO 9001:2015 should be consulted before industrial qualification.
The principal distinction is the breadth of the oligomer distribution. Broad-cut cyclomethicone blends contain measurable concentrations of D4, D5, and D6, as well as linear homologues, which causes fractionation during evaporation. RH-C229 is specified to reduce the mass fraction of D6 and higher oligomers and to limit the low-boiling flash fraction. In a moving-web coater running at 60–120 m/min, a broad-boiling fluid can leave dry patches from early flash-off and wet bands from high-boiling residue. The lot release protocol includes gas chromatographic peak-area integration with an internal siloxane standard; the supplier’s certificate of analysis reports individual cyclic siloxane mass fractions to 0.1% resolution. Generic polydimethylsiloxane fluids do not show a defined volatile plateau, and their evaporation residue after 105 °C for 3 h can exceed 5 wt% depending on molecular weight distribution.
Where quantitative comparison is required, the following representative data may support solvent-replacement screening. The values are class-typical for narrow-cut volatile methylsiloxanes and generic fluids, not batch guarantees for RH-C229.
| Property | Test Method | RH-C229 Nominal Class | D5-rich Cyclomethicone | Linear PDMS 0.65 cSt |
|---|---|---|---|---|
| Kinematic viscosity at 25 °C | ASTM D445-24 | 2.0–4.0 mm²/s | 4.0 mm²/s | 0.65 mm²/s |
| Surface tension at 25 °C | Wilhelmy plate, supplier method | 18–21 mN/m | 18.8 mN/m | 15.7 mN/m |
| Boiling range, 5–95 vol% | ASTM D1078-11(2019) | 175–220 °C | 205–215 °C | 100–101 °C |
| Closed-cup flash point | ASTM D56-22 | ≥55 °C | 76 °C | −2 °C |
| Nonvolatile residue after 150 °C | Internal gravimetric method | ≤0.10 wt% | ≤0.5 wt% | ≤0.05 wt% |
For regulatory compliance, RH-C229 should not be treated as automatically free of cyclic siloxanes. In wash-off cosmetic applications, D4 and D5 are restricted at concentrations equal to or above 0.1% w/w under REACH Annex XVII Entry 70. Formulators must request the lot-specific GC-MS report and calculate the final rinse-off product concentration because supplier specifications are for the neat fluid; dilution reduces the concentration but may reveal background contamination from other ingredients. In industrial applications, the material may fall outside the scope of that restriction, but product stewardship declarations should still be reviewed under RoHS Directive 2011/65/EU where the treated article is electrical and electronic equipment.
The nonvolatile residue of a volatile silicone fluid is not a single molecular species; it consists of high-boiling linear oligomers, cyclic D6 and larger species, and any non-silicone contaminants such as silicone oxidation products or trace metal soaps. The manufacturer’s limit of ≤0.10 wt% after 150 °C forced-air evaporation is a gravimetric index, not a compositional certificate. When RH-C229 is used as a temporary carrier in wire bonding or die-attach cleaning, the relevant endpoint is not bulk residue but the elemental silicon remaining after 150 °C bake. X-ray photoelectron spectroscopy or time-of-flight secondary ion mass spectrometry is used to detect sub-monolayer siloxane contamination at the bond pad. Published data for RH-C229 in wire-bond reliability trials is limited; a low gravimetric residue should not be interpreted as equivalent to a low surface-energy contaminant level. A separate nonvolatile matter test following ASTM D1353-13(2021) may be required for printed circuit assembly shops to satisfy their internal process control plan.
At spray-cell air pressures of 0.15–0.35 MPa, the droplet residence time on low-surface-energy substrates is short. The static surface tension of RH-C229 below 22 mN/m permits wetting of polyimide and epoxy mold compound surfaces with initial contact angles commonly below 20° at 25 °C. Evaporative cooling, however, can condense water on the wet film when relative humidity exceeds 60%, producing micro-haze in optoelectronic coating applications. Substrate pre-drying and dew-point control are recommended for clean lines. The formation of a continuous film is governed by dynamic contact angle, not only static surface tension; if the droplet has lost more than 30% of its mass before contact, the viscosity increase can arrest spreading. High-shear dispersion methods with rotary atomizers require dynamic surface tension measurement by maximum bubble pressure at surface ages below 100 ms; static ring methods will overestimate wetting. Published data for RH-C229 in this specific configuration is limited, so pilot spray trials with the intended nozzle type and air-cap geometry are required.
The evaporation enthalpy of cyclic methylsiloxanes is lower than water but sufficient to cool the wet film during solvent flash-off. Dryer zone settings should be matched to the 10% to 90% mass-loss interval measured by thermogravimetric analysis at 10 °C/min. For a narrow-cut fluid such as RH-C229, a first-zone temperature setpoint of 70–90 °C has been used in coating evaluations, with the second zone held below 110 °C to reduce the risk of oxidative residue formation. A deviation of more than ±5 °C in the first zone can produce visible striping because the evaporation-front position moves along the web. The lower explosive limit must be monitored continuously, with the vapor concentration maintained below 25% of the LEL and interlocked to exhaust fan speed. Process hazard analysis cannot be completed without the lot-specific flash point and vapor pressure from the supplier’s material declaration.
RH-C229 can be evaluated as a nonchlorinated carrier for precision cleaning of stencils and electronic assemblies in a closed-loop ultrasonic degreaser. The equipment should be configured with a freeboard ratio of at least 1.5:1 and a two-stage condenser operated at 45 °C and 10 °C. It is not a drop-in replacement for methylene chloride; solubility parameter differences require higher agitation and longer dwell time for polar flux residues. Removal of solder paste residues from apertures below 0.15 mm pitch has not been independently published for RH-C229. Compatibility with solder mask and conformal coating should be confirmed by solvent rub testing per ASTM D5402-19 or adhesion testing per ASTM D4541-17 before deployment. Avoid containing the fluid in unlined carbon steel at temperatures above 60 °C; moisture and acidic residues may accelerate iron corrosion and discoloration.
Closed containers should be stored at 10–30 °C with dry nitrogen headspace to prevent moisture uptake and headspace oxygen enrichment. Avoid contact with strong Lewis acids, alkali metal hydroxides, and acidic clays, because siloxane bond redistribution may shift volatility and generate low-flash cyclic species. The product is not a neat replacement for aqueous cleaners when hydrophilic soils dominate; a co-solvent or pre-cleaning step may be required.
Within thermoplastic injection molding, RH-C229 is diluted with a high-viscosity polyorganosiloxane release agent at mass fractions of 1–3 wt% and applied to tool surfaces held at 50–60 °C. The carrier evaporates before shot closure, leaving a thin release film. The concentration is critical: below 1 wt%, the release film can be discontinuous; above 3 wt%, the evaporation time may leave residual solvent that creates surface streaks on filled polyamide parts. The processing window is therefore narrow and should be established by molding trials at the intended clamp force. The advantage over mineral spirits or isoparaffin carriers is lower surface tension and lower odor; the limitation is that siloxane deposition on adhesion-critical surfaces can create bonding defects if not removed by plasma treatment. Residual silicones can migrate to the surface of thermoplastics at rates governed by fractional free volume; post-molding adhesion tests should be delayed for at least 24 h at 23 °C before evaluating paint or adhesive strength. Silicone contamination is detectable by X-ray photoelectron spectroscopy with the silicon 2p binding energy near 102 eV. RH-C229 is not recommended as a letdown solvent in room-temperature vulcanizing silicone systems that contain tin or amine catalysts, because residual silanol may initiate condensation and shift rheology; if such use is unavoidable, catalyst compatibility should be confirmed by monitoring viscosity rise over 24 h at 25 °C per ISO 3104:2023.
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