| HS Code | 870919 |
| Base Polymer | Polyamide 11 (PA11) |
| Color | Black |
| Appearance | Fine black powder |
| Melting Point | 186 °C |
| Density | 1.04 g/cm³ |
| Bulk Density | 0.50 g/cm³ typical |
| Particle Size D50 | 80 µm typical |
| Water Absorption 24h | 1.0% typical |
| Tensile Strength | 40 MPa typical |
| Elongation At Break | 300% typical |
| Shore Hardness | D 70 |
| Abrasion Resistance | Excellent |
| Chemical Resistance | Resistant to most solvents, weak acids, and weak bases |
As an accredited Arkema Rilsan Fine Powders ESY BLACK 7298 PA11 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Arkema Rilsan ESY Black 7298 PA11 fine powder supplied in 20 kg bags for electrostatic coating applications. |
| Container Loading (20′ FCL) | 20' FCL: Arkema Rilsan Fine Powders ESY BLACK 7298 PA11 loaded in bags on pallets, kept dry and ventilated. |
| Shipping | Arkema Rilsan Fine Powders ESY BLACK 7298 is a black polyamide 11 powder for coating applications. Ship in sealed, grounded containers to prevent moisture absorption and static accumulation. Avoid dust generation; use proper ventilation and PPE during handling. Transport dry, away from heat, oxidizers, and ignition sources. |
| Storage | Store in a cool, dry area, away from heat, direct sunlight, and ignition sources. Keep the original container tightly sealed to prevent moisture absorption. Avoid exposure to humidity and extreme temperatures. Under these conditions, the powder retains its properties for its designated shelf life. |
| Shelf Life | Shelf life is typically 2 years when stored in original, unopened packaging in a cool, dry place. |
For fluidised-bed dip coating of zinc-phosphated steel spring clips and threaded inserts, Arkema Rilsan Fine Powders ESY BLACK 7298 PA11 is first conditioned in a dehumidified hopper at 20–25 °C and below 40 % RH for at least 4 h; residual moisture above 0.25 wt% creates microblocking in the powder bed and produces film defects when the preheated part is dipped. The substrate is raised to a surface temperature between 270 °C and 330 °C in a forced-air recirculation oven with ±5 °C uniformity, then immersed for 2–6 s in a porous-plate fluidised bed operated at 0.05–0.20 MPa air pressure. Film build is governed by metal heat capacity: sections below 1 mm typically reach 80–180 µm, while sections above 3 mm can exceed 300 µm unless dip time is reduced below 3 s or a vibrating grid is used to eject excess powder. After dip, parts are transferred within 15–30 s to a post-fusion oven at 185–205 °C for 2–6 min to complete flow and levelling. Cross-cut adhesion under ISO 2409:2023 requires blast cleaning to Sa 2½ under ISO 8501-1 and a zinc phosphate conversion layer; without this preparation, delamination occurs at the phosphate-steel interface rather than within the PA11 layer. Salt spray testing under ISO 9227:2022 NSS on zinc-phosphated steel coated at 150–250 µm has published PA11 data reaching 1,000 h with scribe creep below 2.5 mm when an epoxy or phenolic primer is used, though published data for ESY BLACK 7298 in this exact configuration is limited.
| Steel wall thickness | Preheat range | Dip time | Post-fusion schedule | Typical film build |
|---|---|---|---|---|
| <1 mm | 260–300 °C | 4–8 s | 2–4 min at 190–200 °C | 150–250 µm |
| 1–3 mm | 280–320 °C | 3–6 s | 3–5 min at 190–200 °C | 200–350 µm |
| >3 mm | 300–340 °C | 2–4 s | 4–6 min at 190–200 °C | 300–500 µm |
Electrostatic spray application of ESY BLACK 7298 to welded steel wire baskets is constrained by Faraday cage occlusion at wire intersections; the powder must be charged by a high-voltage corona source between 60 kV and 90 kV, with a booth face velocity of 0.3–0.6 m/s. The black-pigmented PA11 has a charge-to-mass ratio that is strongly dependent on relative humidity: below 30 % RH, back ionization on already-coated wireforms leads to orange-peel and microcratering, while above 60 % RH, moisture adsorption reduces transfer efficiency to below 45 %. Wire intersections below 8 mm inside radius require gun-to-part distance of 150–250 mm and powder output of 80–150 g/min; otherwise field lines concentrate on the outer wire surface and leave inner crevices with film thickness below 40 µm. Salt spray resistance under ISO 9227:2022 NSS on 150–200 µm coatings can exceed 1,000 h when a zinc phosphate pretreatment and epoxy powder primer are used; detergent and rinse-aid resistance in hot dishwasher conditions should be evaluated under ASTM D2248-01(2018), and condensation resistance under ASTM D4585. Published data for ESY BLACK 7298 in this exact dishwasher environment is limited.
Because cast aluminium valve covers cannot tolerate preheat temperatures above 260 °C without localised solution heat-treatment effects, ESY BLACK 7298 is applied by electrostatic spray rather than fluidised-bed dip for these components. The part is preheated to 220–250 °C for 10–20 min depending on rib thickness, then sprayed at 70–90 kV with a powder output of 100–180 g/min. Coating thickness on vertical ribs is typically 30–40 % lower than on flat deck areas because of reduced deposition efficiency at high incidence angles; this requires part rotation or auxiliary electrodes. Fusion is completed at 185–200 °C for 3–6 min. Adhesion to aluminium is evaluated by ISO 2409:2023 cross-cut or ISO 4624:2023 pull-off; without a chromate-free conversion coating or thin epoxy primer, adhesion failure is common at the aluminium oxide boundary layer. Acoustic damping and stone-chip resistance on aluminium underbody shields benefit from the low specific gravity of 1.04 g/cm³ measured under ISO 1183-1:2019, but published data for ESY BLACK 7298 on aluminium substrates is limited compared with steel.
On ductile iron pump housings with wall thickness transitions from 4 mm to 20 mm, the permitted preheat window is narrowed to 250–280 °C because higher temperatures can cause retained casting stress release and dimensional distortion. ESY BLACK 7298 is applied by a hybrid process: the housing is rotated in a fluidised bed for 5–15 s, then transferred to a post-fusion oven at 190–200 °C for 6–10 min. The low preheat temperature requires the powder to have sufficient melt mobility in the early coalescence stage; the PA11 melting endotherm near 186–190 °C, measured by ASTM D3418-21, leaves a narrow window in which substrate heat must initiate fusion while the oven supplies additional energy to level the film. Film thickness on internal water passages is controlled by preheating the part with internal air circulation and by using an array of low-voltage charging electrodes to draw powder into shadow zones; without this, internal passage coating thickness falls below 80 µm and corrosion protection under ISO 9227:2022 NSS is compromised. Volute tongue areas require post-fusion inspection under ISO 2808:2019 for dry-film thickness and ASTM D5162-15 for holiday detection; pinhole-free performance is required at 1,000 V test voltage for 200–300 µm coatings.
The deposition of ESY BLACK 7298 onto copper busbar insulation and terminal blocks requires charge-to-mass ratio measurement prior to line start; the carbon black pigmentation of the grade modifies the dielectric response relative to unpigmented PA11 and can shift the usable corona voltage window. A powder sample is conditioned at 23 °C and 30 % RH for 24 h, then sprayed through a bench-scale corona gun at 60–100 kV into a Faraday cup connected to an electrometer; the measured charge-to-mass ratio should remain within the range at which transfer efficiency exceeds 60 % on a flat panel. On busbar geometries, the coating is applied at 70–90 kV to a preheated copper part at 220–250 °C, followed by fusion at 185–200 °C for 3–5 min. Dielectric strength of the fused PA11 layer is evaluated under IEC 60243-1:2013; typical published values for unfilled PA11 coatings from 200–300 µm fall in the range of 20–30 kV/mm, but published data for ESY BLACK 7298 in this specific configuration is limited. The coating must be free of voids at the copper edge radius; a holiday detection threshold of 500 V per 25 µm of specified film thickness is applied under ASTM D5162-15.
Prior to electrostatic application on any substrate, ESY BLACK 7298 is stored in sealed containers below 25 °C and below 40 % RH; opened containers are consumed within 24 h or resealed under nitrogen purge to prevent moisture pickup above 0.25 wt%. Moisture is measured by ISO 15512:2019 or by Karl Fischer titration; blocking resistance is assessed under ISO 8130-8:2005 at 40 °C for 48 h. Powder that fails blocking resistance should be re-sieved through a 125 µm screen before use; agglomerates above this size produce spatter in the fluidised bed and uneven charging in the corona gun. The lower explosion limit of the powder is evaluated under ISO 8130-4:1992; process air velocity must be maintained below the dust cloud explosion threshold and all equipment grounded to ≤10 Ω. Compliance documentation for the grade should include the REACH SVHC declaration under Regulation (EC) No 1907/2006 and RoHS Annex II under Directive 2011/65/EU; published data for ESY BLACK 7298 in direct food-contact applications is limited, and FDA 21 CFR 177.1500 or EU Regulation 10/2011 must be confirmed for the specific final formulation before use.
| Parameter | Standard or regulation | Typical acceptance criterion |
|---|---|---|
| Moisture content | ISO 15512:2019 | ≤0.25 wt% |
| Blocking resistance | ISO 8130-8:2005 | No consolidated lumps after 48 h at 40 °C |
| Particle size distribution | ISO 8130-1:2005 | Oversize retained on 125 µm sieve <1 % |
| Adhesion after pretreatment | ISO 2409:2023 | Cross-cut ≤1 for steel; ≤2 for aluminium |
| Salt spray resistance | ISO 9227:2022 NSS | 1,000 h with scribe creep <2.5 mm on zinc phosphated steel with primer |
| Holiday detection | ASTM D5162-15 | No pinholes at test voltage |
| RoHS restricted substances | Directive 2011/65/EU Annex II | Below maximum concentration values |
| REACH SVHC | Regulation (EC) No 1907/2006 | No SVHC above 0.1 wt% unless declared |
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Arkema Rilsan Fine Powders ESY BLACK 7298 PA11 is a semi-crystalline polyamide 11 coating powder supplied as a black-pigmented fine powder for electrostatic spray and fluidized-bed application. The polymer backbone is derived from 11-aminoundecanoic acid obtained from castor oil; the amide-group density is therefore lower than that of polyamide 6 and polyamide 66, which influences water uptake, dimensional stability, and dielectric behaviour. The ESY designation places the grade within the Rilsan Fine Powders portfolio as a fine-particle electrostatic spray formulation, and the 7298 black reference designates a carbon-black-pigmented lot range. Nominal melt viscosity, particle size distribution, and density for each batch are supplied on the certificate of analysis; representative Rilsan PA11 fine powders exhibit an unfilled resin density of 1.03–1.05 g/cm³ when measured under ISO 1183-1:2019, and a crystalline melting peak between 183 °C and 189 °C under ISO 11357-3:2018. The presence of carbon black in the 7298 grade can alter surface resistivity and tribostatic charge acceptance relative to natural or white Rilsan grades; published data for this specific pigmented configuration is limited, and end users should qualify transfer efficiency with the actual lot according to ISO 8130-10:2021.
Electrostatic spray lines feed the powder through a venturi injector into a corona or tribostatic gun. Typical corona electrode voltages for PA11 coating powders fall in the 50–100 kV range, but the optimal setpoint depends on gun distance, part geometry, and the reduced surface resistivity of the carbon-black-pigmented 7298 grade. Fluidized-bed coating instead relies on immersion of a heated part into an aerated powder bath; the part metal temperature before immersion is generally above 250 °C to build a 300–500 µm film in a single dip. Both processes require controlled relative humidity below 50% to maintain powder fluidity and charge stability.
Water absorption is governed primarily by amide-group concentration. PA11 contains one amide group per 11 carbon atoms, while PA6 contains one amide group per 6 carbon atoms. The lower amide density reduces equilibrium water uptake to approximately 1.8–2.4 wt% at saturation under ISO 62:2008, compared with 9.0–10.0 wt% for PA6. This difference affects polar solvent response, electrical surface conductivity, and dimensional stability of thick coatings. In salt-spray exposure under ISO 9227:2017, PA11 coatings maintain adhesion more consistently than PA6- or PA66-based formulations on steel substrates, provided the substrate is prepared by grit blasting or zinc phosphating under ISO 8501-1:2007 abrasive cleanliness. The property difference also carries into low-temperature impact resistance; semi-crystalline PA11 retains ductile failure at temperatures below 0 °C, while PA6 can become brittle. Impact toughness of a fused coating can be screened by ASTM D2794 direct impact; PA11 coating films exhibit higher reverse-impact values than PA6 at -30 °C, although the exact change for the 7298 grade must be confirmed on the actual substrate.
| Property | Test method | PA11 | PA12 | PA6 |
|---|---|---|---|---|
| Density | ISO 1183-1:2019 | 1.03–1.05 g/cm³ | 1.01–1.02 g/cm³ | 1.12–1.14 g/cm³ |
| Crystalline melting peak | ISO 11357-3:2018 | 183–189 °C | 176–180 °C | 220–225 °C |
| Water saturation | ISO 62:2008 | 1.8–2.4 wt% | 1.5–1.8 wt% | 9.0–10.0 wt% |
| Shore D hardness | ISO 868:2003 | 70–76 | 70–74 | 75–80 |
| Low-temperature impact behaviour | ISO 179-1:2010 | ductile at -30 °C | ductile at -40 °C | brittle at 0 °C |
Powder handling and charging performance of the ESY BLACK 7298 grade are controlled through particle size distribution and moisture content. Laser diffraction analysis under ISO 8130-13:2019 is used to monitor the top size and fines tail; typical fine-powder grades for electrostatic spray are classified below 125 µm, with a controlled sub-10 µm fraction to avoid fluidization dead zones in hoppers. Moisture adsorbed during storage above 60% RH depresses charge-to-mass ratio and promotes spitting, so the powder should be maintained in sealed containers at 20–25 °C. If water content exceeds 0.20 wt%, pre-drying in a dehumidified hopper at 70–80 °C for 2–4 h is recommended before corona or tribostatic application. The exact drying time depends on fluidized bed depth and inlet air dew point; a through-flow hopper with an air dew point below -10 °C gives faster moisture removal than a static oven. Production-scale experience with Rilsan PA11 fine powders indicates that feed variability arising from reclaimed overspray can narrow the process window more than virgin powder lot variation. The 7298 black grade may require lower electrode voltage settings than pale grades because carbon black reduces surface resistivity; the actual voltage adjustment should be verified using a charge-to-mass test per IEC 61340-2-3:2016 or an equivalent powder charging diagnostic.
Overspray reclaim from cyclone or cartridge recovery systems contains a finer particle size distribution than virgin powder because fine particles follow the air stream more readily. When the reclaim fraction added to the virgin hopper exceeds 30 wt% in corona lines, the charge-to-mass distribution can become bimodal; fine particles saturate early and deposit lightly, while coarse particles deposit heavily. This produces film-thickness variation across complex geometries and increased Faraday-cage bridging in recesses. The condition is aggravated when the reclaim contains sub-10 µm fines above 5 wt% of the total powder mass. Sieve analysis under ISO 8130-1:2019 or laser diffraction under ISO 8130-13:2019 should be used to monitor the reclaim before blending. On production lines, the practical control measure is to separate the reclaim stream through a 90–125 µm screen and limit reclaim addition to 20–30 wt%, or to use fluidized-bed mills to renormalize particle size. Published data for the ESY BLACK 7298 grade in high-reclaim corona systems is limited; qualification must include film build, gloss, and salt-spray adhesion on the target substrate.
Fusing and curing schedules for Rilsan PA11 fine powders require peak metal temperatures above the crystalline melt. The powder particles sinter, coalesce, and level as the part metal temperature reaches 220–250 °C; dwell time of 5–10 min at peak temperature is typical for coating thicknesses of 150–400 µm in fluidized-bed lines. For electrostatic spray grade 7298, thinner films in the 80–150 µm range may be used; however, edge coverage and leveling require sufficient heat input. Oven profiling with through-metal thermocouples on the heaviest and thinnest sections is required to avoid underbaking. Underbaked PA11 films show microporosity and reduced adhesion, while overbaking above 260 °C can cause yellowing and oxidative chain scission. Cross-cut adhesion of well-fused films on blast-cleaned steel can be assessed by ISO 2409:2013; class 0–1 is typical when the substrate is prepared to Sa 2½ abrasive cleanliness under ISO 8501-1:2007. Salt-spray resistance under ISO 9227:2017 is commonly tested for 1000 h on phosphated steel; published data for the black 7298 grade is limited, and end-use qualifications should be run with the actual conversion coating. Gloss retention after weathering can be evaluated under ISO 4892-2:2013 with a xenon-arc source; PA11 dark grades may show surface chalking before film failure.
Regulatory compliance for Rilsan PA11 fine powders must be verified against the specific formulation and destination market. The base polyamide 11 resin is covered by FDA 21 CFR 177.1500 for nylon resins, subject to food-contact limitations on type of food and temperature; the pigmented 7298 version requires confirmation that the carbon black and any processing additives meet the same food-contact requirements. Under European Union food-contact law, compliance with Commission Regulation (EU) No 10/2011 requires migration testing for the specific coating thickness and exposure conditions. For industrial and consumer goods, documentation may include REACH registration for the monomer and polymer phase and RoHS Directive 2011/65/EU declarations for the pigment system. The powder is not a thermosetting epoxy or polyester; it cannot be blended with those chemistries, because the cure schedules and melt rheology differ and the resulting film may exhibit intercoat delamination. Contact with strong oxidizing acids, phenol-based strippers, and some chlorinated solvents should be avoided at elevated service temperatures. Storage of opened containers at RH > 60% without subsequent drying will increase moisture-related application defects.
