| HS Code | 941855 |
| Chemical Family | Polyamide 12 |
| Color | Natural |
| Density | 1.01 g/cm³ |
| Melting Point | 178 °C |
| Tensile Strength | 40 MPa |
| Elongation At Break | 300% |
| Tensile Modulus | 1400 MPa |
| Shore Hardness D | 75 |
| Bulk Density | 0.46 g/cm³ |
| Particle Size D50 | 100 µm |
As an accredited Evonik VESTOSINT® 2157 natural color Polyamide 12 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 25 kg sealed bags; free-flowing, natural-color Polyamide 12 powder for coating applications. |
| Container Loading (20′ FCL) | Load 20′ FCL with palletized, stretch-wrapped bags of Evonik VESTOSINT® 2157 natural color Polyamide 12; secure evenly for safe transit. |
| Shipping | VESTOSINT® 2157 ships as non-hazardous polyamide powder in sealed moisture-proof bags or drums. Keep dry, away from heat, open flames, and ignition sources to prevent dust explosion. Use grounded equipment, avoid static buildup, and store in a cool, ventilated area. |
| Storage | Store Evonik VESTOSINT® 2157 natural color Polyamide 12 in its unopened, original packaging in a cool, dry, well-ventilated area. Protect from direct sunlight, heat sources, and high humidity, as the powder is moisture-sensitive. Keep containers tightly sealed when not in use. Under proper conditions, shelf life is typically around two years. |
| Shelf Life | Store unopened in a dry, cool place. Shelf life is approximately two years from delivery date when properly sealed. |
On high-volume dishwasher basket coating lines, Evonik VESTOSINT® 2157 natural color Polyamide 12 is applied to low-carbon steel wire frames that are degreased, pickled, and blast-cleaned to a surface profile of 40–75 µm Rz measured to ISO 4287. The substrate preheat zone is set between 260 °C and 300 °C, measured by contact pyrometer on the thickest weld point, because the melt range of the polyamide 12 powder lies in the region of 176–181 °C under ISO 3146. Baskets are immersed in a fluidized bed with dried, oil-free compressed air at a dew point no higher than −20 °C, and powder is retained on the steel by thermal fusion. Post-fusion is carried out in a separate oven at 180–200 °C for 5–15 min, with time dependent on wire diameter and basket mass. Coating thickness for dishwasher baskets is typically specified at 300–500 µm, verified by ISO 2178 on wire surfaces and weld intersections. In this thickness range, the polyamide 12 layer withstands repeated exposure to alkaline dishwasher detergents at 60–70 °C and pH 10–12, but continuous exposure to oxidizing acid media above 60 °C falls outside the operational boundary of this product.
Edge coverage at welded joints remains the main process-control variable. Preheat temperature measured at the weld is normally set 20–30 °C higher than on plain wire because the weld mass acts as a heat sink. If the weld surface temperature drops below 176 °C, the powder does not fully coalesce, leaving microporosity that is detectable by ISO 4628-2. If the oven temperature exceeds 315 °C for extended periods, the natural PA12 layer may discolour and embrittle. Fluidized bed internals use sintered polyethylene distributor plates, and the powder hopper is maintained at 25–35 °C and relative humidity below 40 % to prevent electrostatic agglomeration. Reclaimed powder is sieved at 125 µm and blended with virgin material at a ratio no greater than 30:70 to control particle-size distribution shift. Qualification of finished baskets typically includes crosshatch adhesion per ISO 2409 after boiling-water immersion for 2 h, impact resistance per ASTM D2794 at 23 °C and −20 °C, and dry film thickness mapping per ISO 2178. The Shore D hardness of the fused coating is usually specified in the range 74–78 when tested to ISO 868 on a flat panel. Water absorption at saturation, measured to ISO 62, is published for PA12 in the range of 1.1–1.5 %, which limits dimensional swelling in wet service. These values are not unique to VESTOSINT® 2157; published data for this specific natural-color grade is limited to typical PA12 coating powder ranges, and end users verify lot-specific values against incoming inspection certificates.
The electrostatic spray application of VESTOSINT® 2157 natural color Polyamide 12 onto stamped steel wire racks for refrigerator evaporator trays and freezer baskets is governed by the Faraday cage effect at wire intersections. The powder is fluidized in a hopper and transported to a corona gun operated at 60–90 kV. Substrate preheat temperature is selected in the range 220–240 °C, because the lower thermal mass of thin stamped sheet allows faster cooling than heavy wire frames. Powder feed pressure is set between 1.5 bar and 2.5 bar, and gun-to-substrate distance is held at 150–250 mm. The applied film thickness is commonly specified at 150–250 µm, measured by ISO 2178. Electrostatic wrap on the rear side of a rack is less predictable than fluidized bed immersion; therefore, critical surfaces are rotated between gloved manual touch-up stations.
| Parameter | Electrostatic spray | Fluidized bed |
|---|---|---|
| Substrate preheat | 220–240 °C | 260–300 °C |
| Powder application | Corona gun 60–90 kV | Immersion dip 5–15 s |
| Fusion/curing | 180–200 °C for 10–15 min | 180–200 °C for 5–15 min |
| Typical film thickness | 150–250 µm | 300–500 µm |
| Thickness verification | ISO 2178 | ISO 2178 |
| Adhesion method | ISO 2409 | ISO 2409 |
Film build on internal corner radii below 5 mm can be as low as 40 % of nominal face thickness due to repulsion of charged powder at the corner. To compensate, line operators preheat to the upper end of the specified range and reduce powder cloud velocity. The melt-flow window of the natural PA12 coating is narrow; below 176 °C the powder does not form a continuous film, while above 240 °C surface oxidation may reduce adhesion. Adhesion of the fused layer to phosphated steel is evaluated by ISO 2409, with a required classification of 0–1 before and after thermal cycling. Refrigerator trays coated with PA12 are then assembled with PVC-dipped wire ends; compatibility between PA12 and plasticizer migration from PVC has to be verified on the specific PVC compound because migration can alter surface tack.
Where cold-formed tubular components are electrostatically powder coated for automotive fluid-handling brackets, the relationship between substrate thermal mass and residual powder charge becomes critical. VESTOSINT® 2157 natural color Polyamide 12 is applied to degreased and zinc-phosphated steel tubes after preheating to 230–250 °C. The tube is rotated on an indexing conveyor to present the surface to the corona cloud. Film thickness is maintained at 180–260 µm and checked with ISO 2178 at 10 mm intervals along the length. After fusion, the coating exhibits a Shore D hardness of 74–78 per ISO 868 and a low coefficient of friction against steel, making it suitable for clips that slide over mating brackets. The low water absorption of PA12, typically 1.1–1.5 % at saturation per ISO 62, prevents the dimensional swelling that would otherwise cause bind on close-tolerance assemblies exposed to road splash.
The main process risk in this sequence is residual electrostatic charge on the powder layer during post-fusion. If the oven temperature rises faster than 8–10 K/min, trapped air below the melting film can form pinholes before the layer is fully sintered. Industrial lines use staged ovens with the first zone set at 180 °C, a second zone at 200 °C, and a total dwell of 10–15 min. Salt-spray testing according to ISO 9227 is used by automotive component specifications for scribe corrosion; acceptance is typically no red rust after 500 h on zinc-phosphated steel when the coating thickness exceeds 220 µm. This scribe-corrosion figure is a function of phosphate layer type and coating thickness, not an inherent property of PA12 alone, and published data for VESTOSINT® 2157 in this configuration is limited. Batch-to-batch variation in powder particle-size distribution influences the powder cloud density, especially in manual touch-up stations.
Outdoor shopping trolleys and wire baskets fabricated from hot-dip galvanized steel are coated with VESTOSINT® 2157 natural color Polyamide 12 after sweep blasting to remove zinc oxide and zinc hydroxide from the surface. The galvanized layer is not removed, but the surface is roughened to 30–50 µm Rz measured to ISO 4287. The preheat oven is regulated to 230–260 °C; the upper limit is selected to avoid diffusion of zinc into the steel and embrittlement of the galvanized intermetallic layer. The PA12 layer is deposited by fluidized bed immersion, with a target film thickness of 250–450 µm. Adhesion of the primer-free system relies on mechanical interlocking rather than chemical bonding. Pull-off adhesion tested to ISO 4624 on flat galvanized plates typically measures above 6 MPa when the blast profile is within specification, but values lower than 3 MPa are observed on heavily oxidized galvanizing that has not been sweep-blasted.
The natural color polyamide 12 is unpigmented and contains no UV-stabilizer package; therefore, continuous outdoor exposure in direct sunlight is not recommended without a topcoat or stabilizer addition. This limitation is an operational boundary, not a defect of the base resin. In hot-dip galvanized shopping trolley applications, the PA12 layer is usually buried under a coloured topcoat or the wire geometry shadows most surfaces. Exposure to combined UV and water at 50 °C may cause gloss reduction and surface chalking within 12–24 months in unpigmented PA12, though published data for this specific VESTOSINT® 2157 grade in natural weathering is limited. The coating is suited for mechanical load-bearing contact areas because PA12 retains toughness at low temperatures; impact testing per ASTM D2794 is often specified at −20 °C and 23 °C with a 1.8 kg falling dart and no cracking.
VESTOSINT® 2157 natural color Polyamide 12 is used for internal coating of brine-handling pipe spools, valve bodies, and pump casings where low-temperature impact and low moisture absorption are required. The substrate is preheated to 220–260 °C, and the powder is injected into the rotating bore or applied by lance-mounted electrostatic spray. The rotation speed is adjusted to produce a uniform melt film on the internal circumference. The target lining thickness is 350–600 µm, measured by an eddy-current gauge at 25 mm intervals. After cooling, a holiday test at 5 V/µm of coating thickness is conducted to detect pinholes; the test voltage is set according to NACE SP0188.
The PA12 layer resists sodium chloride brine at −20 °C to 60 °C and pH 4–10. It is not suitable for continuous contact with strong oxidizing acids such as nitric acid above 10 % at 40 °C, nor for phenols and concentrated formic acid, which dissolve or swell PA12. The liner is qualified by immersion testing per ISO 2812-1 for chemical resistance and by ISO 4624 for adhesion; acceptance is typically no detachment below 6 MPa after 30 days immersion. Thermal cycling between −30 °C and 60 °C is performed to verify that differences in thermal expansion between PA12 and steel do not cause disbonding at flange faces.
| Property | Standard method | Typical industrial requirement |
|---|---|---|
| Dry film thickness | ISO 2178 | 350–600 µm |
| Holiday detection | NACE SP0188 | No discharges at 5 V/µm |
| Pull-off adhesion | ISO 4624 | ≥ 6 MPa |
| Low-temperature impact | ASTM D2794 | No cracking at −20 °C |
| Chemical immersion | ISO 2812-1 | 30 days, no blistering |
Sliding-contact surfaces on aluminum textile machinery components are coated with VESTOSINT® 2157 natural color Polyamide 12 by electrostatic spray followed by fusion at 190–210 °C. The aluminum is first degreased and conversion-coated to produce a chemically anchored oxide layer. The powder layer is deposited at 100–180 µm because thicker films reduce heat transfer from the metal component. After fusion, the coating develops a Shore D hardness of 74–78 per ISO 868, which reduces fibre abrasion compared with uncoated aluminum. The PA12 surface is less susceptible to metal-to-metal galling; component-level sliding wear tests are conducted according to ASTM D3702 or pin-on-disc methods, and mass loss is reported against an uncoated control. Published data for VESTOSINT® 2157 natural color in textile-specific wear rigs is limited; process qualification is therefore based on pilot coating runs using the actual component geometry and fibre type.
The natural PA12 layer should not be post-machined with abrasive stones, because local heat generation above 180 °C can gloss the surface and seal microporosity before service. If dimensional correction is required, a final PA12-compatible topcoat may be applied after mechanical conditioning. Oil mist from textile finishing chemicals can migrate into the PA12 layer over time; users verify compatibility with the specific lubricant package by immersion at 60 °C for 500 h and rechecking Shore D hardness and film adhesion per ISO 2409. The hydrophobic surface of PA12, with water absorption at saturation of 1.1–1.5 % per ISO 62, shows lower equilibrium moisture content than PA6 or PA66, which is critical in humidity-controlled winding rooms.
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Evonik VESTOSINT® 2157 natural color Polyamide 12 is an unpigmented, free-flowing thermoplastic powder based on semicrystalline polyamide 12 resin. The grade is identified by the model designation 2157 and is supplied in natural color without carbon black, titanium dioxide, or organic pigment systems. The base polymer is produced from laurolactam and exhibits a melting peak near 176 °C when measured by differential scanning calorimetry according to ISO 11357-3; solid-state density is approximately 1.01 g/cm³ at 23 °C under ISO 1183-1. The powder is intended for melt coalescence into continuous polyamide 12 films on ferrous and non-ferrous substrates by electrostatic spray, fluidized-bed immersion, or aqueous dispersion coating. Compared with other VESTOSINT polyamide 12 grades, the 2157 natural color variant is positioned for controlled thin-film formation where the absence of added pigments is required for limited color interference, dielectric performance, or post-coating color matching.
Lot-specific certificates of analysis control the numerical release data for each production batch. Where a value is not reproduced in this document, the current Evonik product data sheet and lot certificate remain the controlling references. Polyamide 12 is supplied with REACH-registration obligations verified through the safety data sheet; RoHS 2011/65/EU compliance is typically based on the absence of lead, cadmium, mercury, hexavalent chromium, and brominated flame retardants in the unpigmented formulation. Food-contact suitability is not automatically granted and must be established for the specific end-use under FDA 21 CFR 177.1500 and EU 10/2011, including migration testing of processing aids and any post-coating topcoats.
For PA12 powders, the melting peak at 176 °C is not a sufficient processing set point because film formation requires the substrate to supply enough heat to sinter, coalesce, and level the fused layer after withdrawal from the powder cloud. Production-scale fluidized-bed lines typically operate with substrate preheating in the range of 230–260 °C for PA12 coating powders, with actual surface temperature determined by section thickness, transfer time, and oven circulating-air velocity. On thin-wall steel parts below 2 mm thickness, heat loss during transfer may be high enough to reduce surface temperature by 15–30 °C before immersion, producing incomplete coalescence, rough surfaces, or low gloss in the natural unpigmented grade.
Melt viscosity of PA12 coating grades is characterized by melt volume-flow rate under ISO 1133-1:2022 at 235 °C with 2.16 kg load. Polyamide 12 powders in this product family commonly fall within 10–35 cm³/10 min; exact values for VESTOSINT 2157 natural color are lot-dependent and must be read from the certificate of analysis. At melt temperatures above 280 °C, thermo-oxidative degradation of unpigmented PA12 accelerates in air. This degradation produces yellowing and melt-flow instability. The natural color grade is particularly sensitive to discoloration because it does not contain masking pigments such as carbon black.
Cooling behavior after coalescence also controls the semicrystalline morphology of the final film. Differential scanning calorimetry of PA12 typically records a crystallization exotherm in the range of 146–152 °C on cooling from the melt at 10 K/min. If the coating is cooled too slowly through this interval, larger spherulitic structures can form and reduce impact toughness; if cooled too quickly, the amorphous fraction may be elevated and residual stress can build at the coating-substrate interface. Industrial processes therefore maintain controlled air cooling below 80 °C before mechanical handling.
On corona-charged electrostatic spray lines operating at 60–90 kV, particle-size distribution directly affects transfer efficiency, wrap-around, and minimum achievable film thickness. Fine powders such as VESTOSINT 2157 natural color provide better back-side coverage on recessed geometries than coarse fluidized-bed powders, but excessive fines below 5 µm can reduce fluidization density and produce uneven powder cloud distribution in venturi pumps. Equipment configurations using flat-spray nozzles and fluidized hoppers with 0.5–1.0 bar fluidizing air pressure require controlled powder moisture and free-flowing particle surfaces to avoid spitting or surging in the powder feed system.
Dry powder storage below 30 °C and 60% relative humidity is specified to preserve flowability and prevent moisture uptake. Polyamide 12 absorbs atmospheric moisture; powder exposed to high humidity can agglomerate in the hopper, alter electrostatic charging, and produce microvoids in the coalesced film. If moisture content exceeds 0.2 wt% as measured by ISO 15512, pre-drying with dry air at 80 °C may be used, but prolonged drying at higher temperatures can begin to sinter fine particles and shift particle-size distribution.
Immersion time, part heat capacity, and powder bed density govern film thickness in fluidized-bed application. With a 3 mm steel panel preheated to 250 °C and immersed in a fluidized PA12 powder bed for 2–3 s, fused film thickness commonly falls within 200–400 µm. The exact thickness is not transferable across substrate geometries because thin sections cool faster and thick sections retain heat longer, producing heavier coatings on bosses and lighter coatings on edges. Infrared pyrometry or contact thermocouple measurement of the part surface immediately before immersion is required to establish a repeatable heat-input window.
Film-thickness measurement after cooling is performed according to ISO 2808 or ASTM D7091 for non-destructive dry-film measurement on magnetic or eddy-current instruments. Thickness uniformity across a load-bearing surface should be evaluated with a minimum measurement grid of five points per 100 cm². In natural PA12 coatings intended for thin-film electrical insulation or decorative use, thickness variation greater than ±25 µm across a single component can produce visible color depth differences because the unpigmented film does not hide substrate reflectance uniformly.
Pinhole formation in thin films is influenced by entrapped air, substrate outgassing, and powder moisture. Low-voltage holiday detection according to ASTM D5162 is used at 100–500 V on coatings below 300 µm. For corrosion-protection linings, a pinhole-free result at 100 V is commonly specified, while decorative natural coatings may allow isolated holidays if they do not expose ferrous substrate. Process adjustments for pinhole reduction include reducing fluidizing air velocity, lowering powder moisture, and increasing substrate preheat within the permitted range.
Grit-blasted steel with surface profile 40–75 µm provides mechanical anchorage for PA12 coatings. The substrate must be cleaned of mill scale, rust, and residual oil prior to blasting. Near-white blast cleaning to Sa 2.5 under ISO 8501-1 is a typical surface preparation requirement. After blasting, the surface should be coated before visible oxidation occurs; in high-humidity environments above 60% RH, the acceptable flash-rust interval may be less than 4 h. Zinc phosphate or silane pretreatments are used where additional adhesion performance is required, but an unpigmented PA12 topcoat does not cure chemically at ambient temperature and relies on thermal melting for bond formation.
Adhesion of PA12 coatings is assessed by cross-cut testing according to ISO 2409 or by pull-off testing according to ISO 4624. On properly blasted steel, cross-cut class 0 or 1 is typical for fused PA12 films; values of class 2 or worse indicate insufficient substrate heating, contamination, or moisture interference. Pull-off adhesion values are strongly dependent on film thickness and surface profile; published data for this specific configuration is limited because laboratory values often differ from production-line results. Coating adhesion should be verified on sacrificial parts from the same substrate lot and blast profile as the production run.
Natural color VESTOSINT 2157 is not recommended for continuous service above 80–90 °C because dimensional stability and creep of PA12 decrease with increasing temperature. The product resists oils, greases, and dilute alkalis, but strong acids, phenols, and some chlorinated solvents can degrade polyamide 12. Immersion testing under ISO 2812-1 is recommended before specifying the coating for chemical service.
A direct substitution of VESTOSINT 2157 natural color for a coarser fluidized-bed PA12 grade requires adjustment of powder bed air flow, electrostatic gun settings, and substrate preheat. Coarser powders produce thicker coatings by retaining larger particle mass on hot parts; the finer 2157 grade may deposit a lower coating thickness under identical bed conditions. If the process goal is a thin film of 100–300 µm, the 2157 natural color grade often allows lower preheat temperatures or shorter immersion times than coarse grades with d50 values above 60 µm. Conversely, if the existing line is configured for 400–800 µm thick linings, the use of 2157 natural color may require longer immersion or higher substrate temperatures and may still be unsuitable for high-build applications.
Compared with pigmented VESTOSINT grades, the natural color variant eliminates carbon black and colored pigment effects but may show earlier visual yellowing when exposed to thermal excursions above 260 °C. In transfer-mold, rotomolding, or dispersion-coating applications, the absence of pigments may also reduce viscosity variation from pigment dispersions, but this effect is application-specific and must be quantified by melt-flow testing rather than assumed. Published data for this specific configuration is limited in public literature, so comparative trials on the target production line remain the only reliable basis for substitution decisions.
The powder is incompatible with amine-based additives that can promote premature crosslinking or degradation of the polyamide 12 melt. Water-based dispersions of VESTOSINT 2157 natural color should avoid acidic buffer systems below pH 4 because the amide group can undergo hydrolysis under strongly acidic conditions. Lot-to-lot variation in particle-size distribution may influence electrostatic spray transfer; incoming inspection should record d10, d50, and d90 by laser diffraction according to ISO 13320-1:2020 and compare the width of the distribution against the baseline established for the specific coating line.
Specification control for incoming powder should include bulk density, moisture content, particle-size distribution, and melt flow rate. A powder with bulk density below 0.35 g/cm³ can indicate excessive fines, agglomeration, or altered fluidization behavior. A median particle size above the typical fine-powder range may reduce pinhole resistance in thin films and increase orange peel. These parameters are more informative than a single average particle size because the shape of the distribution affects both electrostatic deposition and packing density in the fluidized bed.
| Parameter | Test basis | Expected control range or typical value |
|---|---|---|
| Bulk density | ISO 60 | 0.35–0.45 g/cm³ |
| Median particle size d50 | ISO 13320-1:2020 | 20–30 µm |
| Melting peak temperature | ISO 11357-3 | 176–180 °C |
| Solid-state density | ISO 1183-1 | 1.01–1.03 g/cm³ |
| Water absorption at saturation | ISO 62 | 1.4–1.5 wt% |
| Residual moisture after drying | ISO 15512 | ≤0.2 wt% |
These values represent typical PA12 powder data and incoming-inspection targets. They are not a substitute for release limits on the lot certificate. VESTOSINT 2157 natural color should be sampled from original sealed packaging using a clean stainless-steel thief sampler to avoid cross-contamination with pigmented powder residues.
