Super Smooth and Soft Silicone Oil RH-NB-8113

Super Smooth and Soft Silicone Oil RH-NB-8113 is supplied as a 100 % active aminoethylaminopropyl polydimethylsiloxane fluid, manufactured without aryl solvents or xylene cut. The linear polysiloxane backbone carries pendant aminofunctional groups whose amine density is controlled to favour secondary substitution over primary substitution; this distribution is significant because primary amine sites are the principal precursors of thermal yellowing in amino silicone finishes. In concentrated form the product is a clear to slightly hazy liquid with a mild aminic odour. Table 1 lists the specification ranges used for production batch release and incoming quality-control verification.

In exhaust application at a material-to-liquor ratio of 1:8 to 1:12 on overflow-jet or soft-flow machines, RH-NB-8113 is introduced as a pre-diluted acidified dispersion at 0.5–2.0 % on weight of fabric. The bath is heated to 40–50 °C and adjusted to pH 5.0–6.0 with acetic acid or citric acid before the fluid is injected through the side tank. Circulation for 20–30 min is normally sufficient for cotton jersey and interlock. Exhaustion is driven by protonation of the amine groups below the isoelectric point of the fibre surface; rapid pH drop below 4.5 should be avoided because it can cause premature exhaustion and oil spot deposition on high-speed jets. On package-dyeing machines with pump circulation rates above 300 L/kg/h, the pre-emulsion should not be dosed directly into the pump suction line. Shear forces in the primary pump can split the acidified dispersion, leading to silicone redeposition on the yarn package and subsequent winding friction increases. Published data for this specific configuration in high-temperature polyester dyeing is limited; compatibility with disperse dye dispersants and carrier solvents must be evaluated in the plant before bulk use.

Why Does RH-NB-8113 Exhibit Lower Yellowing Than Conventional Amino Silicone Fluid Grades?

Thermal yellowing in aminofunctional silicone films is dominated by oxidative conversion of primary amino groups to imine and quinoid chromophores during cure. The amine value specification of 0.25–0.45 mg KOH/g for RH-NB-8113 is lower than the 0.6–0.9 mg KOH/g range common for conventional aminoethylaminopropyl fluids. Because the concentration of available primary amine is reduced and the substitution pattern is biased toward secondary aminofunctional groups, cure-induced chromophore formation is lower. In comparative pad-dry-cure trials on bleached cotton poplin at 20 g/L working concentration and 180 °C for 30 min, AATCC TM 110-2015 yellowing measurements produced ΔE values of 0.8–1.2 for RH-NB-8113 and 1.8–2.6 for a conventional fluid at equivalent add-on. The same method is used for quality control when optical brightener compatibility is critical. Kawabata KES-FB4 surface friction measurements on cured poplin at 10 g/L give a mean coefficient of friction of 0.18–0.22 for RH-NB-8113, compared with 0.25–0.30 for a conventional amino fluid and 0.30–0.35 for a non-reactive dimethyl silicone oil at the same bath concentration. These data support the designation “smooth and soft” in the product name as a measured surface-friction characteristic rather than a subjective descriptor.

Batch-to-batch viscosity data after 24 h settling at 25 °C show a coefficient of variation below 3 % when sampled from 200 kg drums and 1000 kg intermediate bulk containers after low-shear nitrogen mixing. Amine value is controlled within ±0.03 mg KOH/g because wider variation alters acid demand in pad bath preparation and affects the pH at which exhaustion occurs. In a 500 L stainless steel mixing vessel with a four-blade axial turbine at 150 rpm, the pre-emulsion viscosity remains below 500 mPa·s at 25 °C, which permits transfer by lobe pumps without cavitation. Above 1000 s⁻¹, the fluid exhibits shear thinning; this is relevant when passing through high-shear rotor-stator devices because local heating above 40 °C can accelerate siloxane hydrolysis.

When RH-NB-8113 Is Pre-Dispersed at 15–20 wt% for Cold-Setting Softener Bases

When the fluid is converted into a 15–20 wt% oil-in-water pre-emulsion, mechanical pre-dispersion is required because the product is not supplied as a ready-to-use emulsion. A rotor-stator mixer operating at 1500–3000 rpm for 10–15 min in demineralised water at 20–30 °C produces a coarse pre-emulsion. Subsequent two-pass high-pressure homogenization at 300–500 bar reduces median particle size to D50 < 200 nm, measured by laser diffraction. The order of addition is critical: the water phase is first adjusted to pH 5.0–5.5 with acetic acid, and the silicone fluid is introduced into the acidified water under agitation. Adding acid after the silicone fluid can create localised low-pH zones that promote gelation of aminofunctional siloxane oligomers. Nonylphenol ethoxylate-free emulsifiers with an HLB of 10–13 are suitable for stable pre-emulsions; the exact ratio should be determined by phase diagram rather than fixed for all water hardness values.

On a production padder with a mangle expression of 70–80 %, the pre-emulsion is diluted to 5–20 g/L working concentration. Drying at 110–130 °C followed by curing at 150–170 °C for 60–120 s produces a crosslinked silicone film. The practical curing window is approximately ±5 °C when fabrics contain stilbene-based optical brighteners; below 150 °C wash fastness falls, and above 175 °C yellowing risk increases. On a 12-chamber stenter frame, unequal airflow above 2 m/s differential between top and bottom nozzles has been observed to create side-to-side hand variation when add-on exceeds 15 g/L. For terry towelling at add-on levels above 10 g/L, a hydrophilic nonionic softener or silicone polyether terpolymer should be co-processed to maintain AATCC TM 79 drop absorption below 5 s after one laundering cycle because the aminofunctional film is hydrophobic.

In rinse-off hair conditioning formulations, RH-NB-8113 is used at 0.5–2.0 % active in the final emulsion after fatty alcohol lamellar gel formation and cooling below 40 °C. Homogenization at 5000–8000 rpm for 5 min is typically sufficient to produce a particle size below 300 nm when combined with cetrimonium chloride at 0.5–1.0 %. The amine-functional silicone deposits on the hair fibre surface during rinsing and reduces combing force. Published data on this specific silicone oil in hair care is limited, and formulation compatibility with cationic polymers must be tested above 0.2 % cationic charge because coacervation can destabilize the emulsion.

Relative to dimethyl silicone oils, RH-NB-8113 contains aminofunctional substituents that protonate in acidified processing baths and provide substantivity to cellulosic substrates without an external cationic surfactant. Relative to conventional amino silicone fluids, the amine value is lower, which shifts the hand from an elastic or rubbery film toward a smoother, lower-friction film and reduces yellowing. Relative to ready-to-use silicone emulsions, the 100 % active supply form lowers transport mass per kilogram of active siloxane and permits selection of emulsifier chemistry according to local effluent requirements. The principal operational difference is that RH-NB-8113 must be pre-emulsified; it cannot be dosed directly into an exhausted bath without mechanical dispersion. Table 2 summarises the comparative profile against common silicone softener fluids.

Because the fluid is non-ionic in concentrated form and weakly cationic when acidified to pH 5.0–5.5, it is not compatible with strong anionic wetting agents unless an amphoteric compatibiliser is introduced. In pad bath preparation, the product should be added after the acid but before cationic or nonionic additives. For textile mills using water hardness above 200 mg/L CaCO₃, a chelating agent based on polyphosphate or EDTA should be added first to avoid calcium salt precipitation in the machine sump.

Storage, Compatibility, and Operational Boundaries

Store RH-NB-8113 in sealed containers between 5 °C and 40 °C. Extended exposure to air causes surface skinning; partially emptied containers should be nitrogen-blanketed or consumed within 30 days. The product has a shelf life of 12 months from the date of manufacture under these conditions. Do not combine the concentrated fluid with strong anionic surfactants, highly alkaline solutions above pH 9, or strong oxidising agents; aminofunctional siloxanes can gel or lose amine value under these conditions. In aqueous dispersion, maintain pH 5.0–6.0 and avoid hold times longer than 24 h because hydrolysis of the siloxane backbone can shift particle size and deposition behaviour. For silicone oil handling, local exhaust ventilation is recommended during bulk transfer because trace amounts of low molecular weight cyclosiloxanes may be present. Safety data sheet controls apply; no product should be released to drains because the fluid is water-insoluble and may form surface films in biological wastewater treatment systems.