| HS Code | 982115 |
| Productname | Silicone Leveling Agent RH-T1023 |
| Chemicalcomposition | Polyether-modified polysiloxane |
| Appearance | Colorless to light-yellow transparent liquid |
| Activecontent | ≥98% |
| Viscosityat25c | 100-500 mPa·s |
| Densityat25c | 1.00-1.05 g/cm³ |
| Refractiveindexat25c | 1.43-1.45 |
| Ionicity | Nonionic |
| Solubility | Soluble in xylene, butyl acetate, and other organic solvents |
| Recommendeddosage | 0.1-1.0% of total formulation |
| Applicationsystems | Solvent-based coatings, inks, and UV-curable coatings |
| Mainfunction | Improves leveling, flow, and substrate wetting |
| Flashpoint | >100 °C |
| Storageconditions | Store in a cool, dry, ventilated place away from direct sunlight |
| Shelflife | 24 months in unopened original packaging |
| Packaging | 25 kg plastic drum or as customized |
As an accredited Silicone Leveling Agent RH-T1023 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Silicone Leveling Agent RH-T1023 is supplied in 200 kg iron drums or 25 kg plastic drums for safe industrial storage and transport. |
| Container Loading (20′ FCL) | 20′ FCL container loading: Silicone Leveling Agent RH-T1023 drums are palletized, secured, and evenly distributed for safe ocean transport. |
| Shipping | Silicone Leveling Agent RH-T1023 is packed in sealed, labeled industrial containers and shipped by land, sea, or air in accordance with its SDS and applicable transport regulations. Keep containers dry, cool, ventilated, and protected from sunlight, heat, and leakage during handling and transit. |
| Storage | Store Silicone Leveling Agent RH-T1023 in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep containers tightly closed to prevent moisture and contamination. Avoid freezing and extreme temperatures. Segregate from strong acids, bases, oxidizers, and foodstuffs. Follow the manufacturer’s SDS and local regulations for shelf life and safe storage. |
| Shelf Life | RH-T1023 has a typical shelf life of 12 months in its original unopened container, stored at room temperature away from sunlight and moisture. |
In solventborne high-solids two-component polyurethane topcoats for metal finishing lines, RH-T1023 is introduced during the final letdown phase after pigment grinding and after viscosity adjustment with butyl acetate or xylene. The dosing window is 0.10–0.30 wt% of total formulation weight. Field data from air-assisted airless spray lines operating at 0.12–0.18 MPa fluid pressure and 0.25–0.35 MPa atomizing air show that pre-dilution at 1:1 by weight in butyl acetate before addition prevents seeding and reduces crater defects associated with localized low surface energy. Addition is made under radial-flow impeller agitation at 800–1000 rpm for 10–12 min; batch temperature is maintained at 20–35 °C. The additive must not be charged into the pigment grind because it will compete with pigment wetting and can destabilize dispersion rheology. Compliance verification for this application draws on ASTM D2369-20 for volatile organic compound content, ASTM D3359-17 for adhesion, ASTM D523-14 for specular gloss, ASTM D4062-16 for leveling, and ISO 2884-1:2020 for high-shear viscosity. Terminal finished product types include machine tool housings, industrial shelving, electrical cabinets, and other factory-applied metal components. Operational boundary conditions require that overcoating be completed within 24 h at 23 ± 2 °C and 50 ± 5% relative humidity; at addition levels above 0.50 wt%, intercoat adhesion loss is observed after sanding due to silicone monolayer saturation at the film-air interface.
| Standard designation | Test method area | Verification boundary in 2K PU topcoat |
|---|---|---|
| ASTM D2369-20 | Volatile organic compound content | Documented and evaluated against local permit threshold; many industrial maintenance formulations target 420 g/L or lower. |
| ASTM D523-14 | Specular gloss at 20°, 60°, 85° | 60° gloss after 7 d must meet customer specification. |
| ASTM D3359-17 | Cross-cut adhesion to prepared steel | Classification 4B or better after 24 h overcoat window. |
| ASTM D4062-16 | Leveling of organic coatings | No continuous ridges at 0.10–0.30 wt% dosage. |
| DIN EN ISO 2431:2019 | Flow time | Adjusted to 20–30 s in a 4 mm cup or OEM-approved equivalent. |
Waterborne acrylic and acrylic-alkyd trim enamels require RH-T1023 dosing of 0.20–0.50 wt% on total formulation after the pH is adjusted to 8.0–9.0 with dimethyl ethanolamine or ammonia solution. Pre-dilution in dipropylene glycol dimethyl ether at 1:2 ratio is required to avoid local gel particle formation when the additive contacts anionic surfactant micelles. The dilution is added under low-shear paddle mixing at 600–900 rpm for 10–15 min at 15–30 °C; high-shear flash mixing introduces micro-foam that persists after film formation. Production application uses HVLP spray at 0.15–0.20 MPa atomizing air, with wet film build 80–120 µm to reach dry film 30–45 µm. Compliance for this segment is anchored to EU Directive 2004/42/EC, Annex II, Category A/d waterborne trim and cladding paints, VOC limit 130 g/L ready-to-use, and to EN 71-3:2019+A1:2021 migration limits if the coated article is intended for children’s wooden furniture. Terminal finished product categories include interior wood trim, cabinet doors, engineered wood moldings, and solid wood frames. Addition above 0.50 wt% reduces water resistance and can destabilize emulsion freeze-thaw stability as evaluated by ASTM D2243-20.
UV-curable clear coatings for plastic substrates incorporate RH-T1023 at 0.10–0.35 wt% on total formulation, pre-dissolved in tripropylene glycol diacrylate at 1:3 ratio before the photoinitiator package is added. The ordering is material because the silicone must not be exposed to high-intensity mixing with acrylate oligomers and photoinitiators at >30 °C, which can generate microgels that later appear as surface seeds. Production-scale UV lines use a 395 nm UV-LED array delivering 800–1500 mJ/cm² at 500–1000 mW/cm² irradiance, or a mercury arc H-bulb rated 120 W/cm, at belt speeds of 8–15 m/min. The finished film is applied at 15–25 µm dry film thickness on polycarbonate, acrylic, or ABS substrates. Compliance measurements include ISO 15184:2020 for pencil hardness, DIN EN ISO 2409:2013 for cross-cut adhesion, ASTM D523-14 for gloss, and ASTM D4060-19 for Taber abrasion. Terminal finished product categories include consumer electronics housings, cosmetic packaging components, and automotive interior plastic trim. When addition exceeds 0.35 wt%, the silicone-rich air interface can delay surface conversion; published data for this specific configuration is limited, but inline quality checks use methyl ethyl ketone double rubs per ASTM D5402-19 to ensure through-cure.
Thermosetting powder coatings based on carboxylated polyester and TGIC or β-hydroxyalkylamide hardeners require RH-T1023 in the premix at 0.3–0.8 phr before extrusion. The premix is blended for 3–5 min at 1000–1500 rpm in a high-intensity mixer. The production process proceeds through a co-rotating twin-screw extruder with L/D 28:1–40:1, screw speed 250–350 rpm, and controlled melt temperature 100–115 °C. Temperature control above 120 °C is critical because silicone droplet coalescence at the melt surface creates point craters and reduces the effectiveness of the additive in the recovered powder stream. The extrudate is cooled on a chilled belt, broken into flakes, and ground in an air classifier mill to a particle size distribution with D50 30–45 µm and D90 ≤ 90 µm. Electrostatic spray application is performed at 60–100 kV corona charging, followed by curing at 180–200 °C substrate temperature for 10–15 min. Compliance is anchored to Qualicoat architectural powder coating specification current edition, AAMA 2604-20, ISO 2810:2020 for natural weathering, and ASTM D2794-93(2019) for impact resistance. Terminal finished product types include architectural aluminum profiles, domestic appliance panels, and powder-coated steel furniture components. Operational boundaries are set by reclaim-to-virgin powder ratio, which should not exceed 30:70 unless the reclaim is monitored for silicone accumulation; above 1.0 phr additive loading, intercoat adhesion in two-coat systems becomes inconsistent and must be verified by ASTM D3359-17. Pre-drying of powder is required if storage humidity exceeds 60% relative humidity before electrostatic application.
For solventborne automotive OEM clearcoats applied over basecoat in high-velocity automated paint shops, RH-T1023 is dosed at 0.05–0.20 wt% on total clearcoat formulation. The additive is combined with the clearcoat during circulation in the mix room and must be added before the final viscosity adjustment with n-butyl acetate or 2-heptanone to avoid concentration gradients in the ring main. Application uses high-speed rotary bell atomizers at 45–70 kV electrostatic charge, bell speeds of 30,000–50,000 min⁻¹, and dry film build of 35–55 µm after baking at 140–150 °C for 20–30 min. This low dosage is sufficient to suppress cratering and improve leveling without forming an intercoat adhesion barrier during reflow or repair overbaking. Compliance measurements include ASTM D2244-23 for color, ASTM D523-14 for gloss, ASTM D3359-17 for adhesion, and SAE J2527 for xenon arc accelerated weathering. Terminal finished product types are passenger vehicle clearcoats and light commercial vehicle cabin finishes. Published data for this specific configuration is limited for exact sag behavior at 0.20 wt% on vertical surfaces; therefore, sag resistance must be confirmed by ASTM D4400-18 or a rotational viscometer. Addition above 0.20 wt% is unnecessary and may reduce repair adhesion after 72 h bake.
In polyester-melamine and polyvinylidene fluoride coil coating systems for prepainted metal, RH-T1023 is added at 0.05–0.20 phr on wet paint, pre-diluted in butyl glycol or an aromatic hydrocarbon blend at 1:2 ratio. The downstream production process uses a reverse roll coater operating at line speeds of 100–150 m/min, with wet film thickness typically 20–60 µm, followed by forced convection curing at peak metal temperature 220–260 °C for 30–60 s. The additive prevents crater formation from airborne oil mist and roll application turbulence, but above 0.20 phr it can create a silicone-rich top layer that reduces foam adhesion in laminate systems and interferes with polyurethane adhesive bonding. Compliance is referenced to EN 13523-1, EN 13523-2, EN 13523-3 for coil coated metal test methods, and ASTM D4145-10 for flexibility of prepainted sheet. Terminal finished product types include prepainted steel and aluminum coils for roofing, wall cladding, garage doors, and domestic appliance panels. Published data for this specific configuration is limited below 0.05 phr; at that level, crater suppression is inconsistent on high-speed lines where substrate temperature fluctuates by more than ±5 °C.
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Silicone Leveling Agent RH-T1023 is a polyether-modified polydimethylsiloxane copolymer supplied as a solvent-free, high-active liquid for solvent-borne, high-solids, and radiation-curable coating formulations. The product is identified by model designation RH-T1023 on batch certificates and is distributed as a single-component additive. The polymer architecture combines a siloxane backbone of controlled chain length with pendant polyether chains; this structure produces limited compatibility with alkyd, polyester-melamine, polyurethane, epoxy, and acrylate binders. The resulting controlled incompatibility allows the additive to migrate to the coating-air interface during solvent flash-off, where it equalizes surface tension gradients that would otherwise generate cratering, orange peel, and edge retraction. The material is not a defoamer, and its effect on foam dissipation in waterborne systems is indirect rather than primary.
In comparison with an unmodified polydimethylsiloxane of similar siloxane chain length, the polyether modification shifts the phase behavior from strong incompatibility toward a more balanced interaction with polar binders. This reduces the tendency to form persistent silicone-rich surface layers. The migration rate is therefore slower, and the equilibrium surface excess is lower. These characteristics become significant in multi-layer coating systems where intercoat adhesion and printing or adhesive bonding after topcoat application are acceptance-critical. The exact migration rate is formulation-dependent and is influenced by solvent type, binder polarity, pigment volume concentration, and bake schedule.
Physically, RH-T1023 is a low-volatility liquid with a flash point above 100 °C when tested as the neat product under ISO 1523:2002. The low vapor pressure is consistent with a siloxane backbone; emission from the cured film is generally low, but volatile cyclic siloxanes can be present in trace amounts depending on manufacturing. The product does not contain water, aromatic solvents, or volatile organic compounds as supplied. This solvent-free composition allows formulators to adjust solvent balance independently and simplifies documentation for the additive itself. However, the absence of solvent increases the viscosity of the neat liquid; pumping from drums at low temperature may require heated lines or piston pumps capable of handling 500 mPa·s at 10 °C.
The supplier-controlled release limits are summarized below. These values are derived from the batch certificate of analysis and are measured on the neat additive unless a solvent dilution is specified.
| Parameter | Typical value or range | Test designation |
|---|---|---|
| Appearance at 25 °C | Clear to slightly hazy liquid | Visual inspection |
| Active content | ≥ 98 % | ISO 3251:2019 |
| Viscosity at 25 °C | 250–500 mPa·s | ISO 3219:1994 |
| Density at 25 °C | 0.99–1.03 g/cm³ | ISO 2811-1:2023 |
| Flash point | > 100 °C | ISO 1523:2002 |
| Surface tension at 0.1 wt% in xylene | 22–24 mN/m | ISO 304:1985, Wilhelmy plate |
Non-volatile residue is determined at 150 °C for 10 min under forced air. Viscosity is shear-rate dependent below 5 °C; the product thickens but returns to specification after conditioning to 20–30 °C. Flash point measurements above 100 °C are determined by closed-cup equilibrium method; pre-dilutions in butyl acetate or xylene take the flash point of the solvent phase. The density range supports weight-to-volume dosing on gravimetric metering equipment. The surface tension value in the table is a comparative screening value, not a lower plateau; further reduction may occur at higher concentrations but is not required for crater suppression in most solvent-borne clearcoats.
Batch-to-batch variation of the siloxane chain length is monitored indirectly by viscosity. A shift from 250 mPa·s to 500 mPa·s can change the migration rate and surface excess; color-critical clearcoats are therefore controlled within ±50 mPa·s. The active content by ISO 3251:2019 is not sufficient to detect low molecular weight cyclic siloxane impurities; gas chromatography should be used where volatile organic compound contribution must remain below a specific limit. Storage is recommended at 5–35 °C in sealed containers. Dry nitrogen blanketing is not required for normal use, but extended exposure to humid air can introduce water into the container. The product is hydrophobic and is diluted in aromatic hydrocarbons, esters, ketones, and glycol ethers; water dilution is not applicable. In acid-catalyzed formulations, the polyether linkage can be hydrolytically sensitive over long storage periods. Published data for this specific configuration is limited, so formulations containing sulfonic acid catalysts should be tested for viscosity drift and turbidity after 4 weeks at 40 °C.
The recommended addition range is 0.05 wt% to 0.5 wt% based on total formulation mass. In solvent-borne polyester-melamine clearcoats, a concentration of 0.1 wt% reduces the static surface tension measured by Du Noüy ring from 34 mN/m to 23 mN/m. The additive is introduced after pigment dispersion, either as a 10 wt% pre-dilution in butyl acetate, xylene, or propylene glycol methyl ether acetate. A high-shear dissolver operating at a tip speed of 5–8 m/s for 15 min is sufficient for homogeneity. Prolonged high-shear processing above 60 min does not improve leveling because the additive migrates to the interface after application rather than during mixing. In radiation-curable urethane acrylate systems, the additive is dissolved in monomer before oligomer addition to avoid seeding of gel particles.
The mechanism is interfacial, not bulk flow modification. During solvent evaporation, surface tension gradients develop at the flash-off edge, around airborne particulates, and over substrate irregularities. The additive lowers the local surface tension and induces Marangoni flow from lower-surface-tension regions toward higher-surface-tension regions. This flow equalizes film thickness before the coating viscosity rises beyond the point where flow is possible. In high-solids systems with low solvent volume, the additive can reach the air interface within 30 s after drawdown. If the surface excess becomes too high, the film develops a low-gloss haze and becomes difficult to overcoat. Cross-cut adhesion according to ISO 2409:2020 should remain at grade 0 or grade 1 on the intended primer. A drop to grade 2 or grade 3 indicates excessive surface migration or insufficient surface preparation before recoat.
The additive does not function by raising low-shear viscosity. Rotational viscometry at 1 s⁻¹ and 23 °C in a polyester-melamine clearcoat shows a change of less than 5 % at 0.1 wt%; the leveling improvement is therefore not attributable to a thicker wet film. This differentiates RH-T1023 from high-molecular-weight silicone additives that also act as rheology modifiers. Over-addition above 0.5 wt% can stabilize air bubbles in high-shear roller application. Foam height in a mechanical foam test rises beyond 30 mm at 0.75 wt% in a solvent-borne alkyd under high-shear mixing. For formulations without silicone-free defoamers, the lower end of the recommended range is preferred. In spray-applied two-component polyurethane topcoats, crater suppression at 0.1 wt% can be evaluated by gloss retention after a 10 min flash-off at 23 °C and 50 % RH, measured according to ISO 2813:2014. The wetting of contaminated substrates may be reduced if the additive migrates ahead of the liquid front; this condition is assessed by contact angle measurement on the actual substrate.
The following comparison is based on standardized coating tests in a solvent-borne polyester-melamine clearcoat. Results are batch and formulation dependent and are comparative rather than absolute acceptance limits.
| Parameter | RH-T1023 | Acrylate leveling agent | Fluorosurfactant | Unmodified PDMS 350 cSt |
|---|---|---|---|---|
| Typical dosage, mass % | 0.05–0.5 | 0.2–1.0 | 0.05–0.3 | 0.005–0.1 |
| Static surface tension at recommended dose | 22–24 mN/m | > 28 mN/m | < 18 mN/m | 20–22 mN/m |
| Recoatability after bake | Moderate above 0.3 wt%; validate by ISO 2409:2020 | Good | Poor; surface energy remains reduced | Poor; may require sanding or plasma treatment |
| Foam stabilization | Low to moderate | Low | Moderate to high | Moderate |
| Slip and mar resistance | Moderate | Low | High | High |
| Thermal stability at 200 °C | Stable in short bake cycle | Stable | Decomposition possible | Stable |
Acrylate leveling agents lower surface tension to a limited degree; the minimum surface tension typically remains above 28 mN/m. This is acceptable for orange peel but not for severe cratering caused by silicone contamination or aerosol overspray. Fluorosurfactants reduce surface tension below 18 mN/m, but their low-energy surface can impair adhesion of adhesives, inks, and subsequent coats. Unmodified polydimethylsiloxane of 350 cSt is highly surface-active but forms discrete silicone-rich phases when overdosed, leading to cratering and intercoat delamination. RH-T1023 occupies a middle position: moderate surface tension reduction with controlled migration, lower foam stabilization than fluorosurfactants, and better recoatability than unmodified PDMS at equal surface tension reduction.
Migration kinetics differentiate the classes more than equilibrium surface tension alone. A fluorosurfactant and an unmodified PDMS often reach a persistent surface excess within seconds; RH-T1023 requires longer, and its surface concentration is moderated by the polyether segment. This produces less surface accumulation after repeated application cycles. In multi-layer automotive refinish systems, recoat adhesion after sanding is tested by ISO 2409:2020; formulations with RH-T1023 above 0.3 wt% may require solvent wipe or scuffing to maintain grade 1. Formulators should not extrapolate performance from one clearcoat to another without conducting cross-coat adhesion trials on the actual stack. Compared with other polyether-modified silicones, the compatibility window is set by the ethylene oxide-to-propylene oxide ratio and the siloxane chain length. A higher ethylene oxide content increases water compatibility but reduces thermal stability and can raise foam stabilization. A longer siloxane chain lowers surface tension more aggressively but worsens recoatability. RH-T1023 is balanced for solvent-borne and high-solids systems; it is not optimized for waterborne formulations, where a more hydrophilic polyether modification is usually required.
Production coil coating lines running polyester-melamine topcoats on hot-dip galvanized steel at line speeds of 60–120 m/min observe different leveling behavior depending on where RH-T1023 enters the coater. If the additive is charged directly into the millbase, the circulation system can hold a silicone-rich phase that deposits on the first 200–300 m of coated substrate after a batch change. Pre-dilution to 10 wt% in butyl acetate and injection into the let-down tank with gentle agitation avoids this defect pattern. The relevant coater parameters are gravure roll speed ratio, coater pan turnover rate, and flash-off zone temperature. At line speeds above 120 m/min, the solvent evaporation rate in the flash-off zone should be kept below 2 g/(m²·s) to allow the additive to migrate before surface fixation; otherwise, leveling defects may be frozen into the film.
In a two-component polyurethane line using high-volume low-pressure spray, the additive is typically injected into the pre-diluted catalyst feed to avoid the high shear of the mixing block. If injected undiluted, the viscous drop can remain as an inclusion and produce localized craters that are visible only after 24 h hardness development. This failure mode is distinct from bulk incompatibility and is corrected by pre-dilution, not by increasing agitation. The injection point should be verified with a clear drawdown sample from the circulation loop before the coater head. Documentation for RH-T1023 should include an SDS compliant with Regulation (EC) No 1907/2006 Annex II. The product is not intended as a direct food-contact material; use in coatings for food-contact articles requires verification of the finished coating under 21 CFR 175.300 and relevant migration limits. No RoHS-restricted substance exceedance is expected based on the silicone backbone, but the final product must be assessed per Directive 2011/65/EU Annex II. For aerospace or military coating specifications, batch approval is typically tied to an agreed viscosity window, infra-red spectrum, and silicone content by X-ray fluorescence.
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