EMS-Grivory Grilamid L 22A W 40X Nylon 12, Dry designates an unreinforced polyamide 12 injection-molding and extrusion grade from the Grilamid L product family. The L 22A base is a medium-viscosity PA12 synthesized from laurolactam; the W 40X suffix in EMS-Grivory nomenclature identifies the supplier’s specific stabilization and pigmentation configuration, generally associated with weathering resistance and black color. The Dry condition indicates that reported mechanical values refer to low-moisture, dry-as-molded material rather than moisture-conditioned material. PA12 has a lower amide group density than PA6 or PA66, yielding water absorption at saturation near 1.4–1.6 wt% under ISO 62, a density near 1.01 g/cm³ under ISO 1183-1:2019, and a melting point near 176–180 °C per ISO 11357-3. The grade is suited to clips, snap-fit fasteners, electrical connector bodies, pneumatic fittings, exterior brackets, and cable-management components requiring low moisture uptake, sub-zero impact toughness, resistance to oils and fuels, and UV exposure tolerance.

What does the dry-as-molded condition imply for nylon 12 property reporting?

Polyamide 12 is hygroscopic, but less so than short-chain polyamides. At 23 °C and 50 % RH, equilibrium water absorption for unreinforced PA12 is approximately 0.7 wt%; saturation in water is about 1.4–1.6 wt%. Dry-as-molded values are therefore measured on specimens with residual moisture below 0.10 wt%, usually after sealed-bag storage or desiccant drying. Moisture acts as a plasticizer in PA12, so conditioned specimens show reduced tensile modulus and yield stress and increased elongation. The difference between dry and conditioned data is smaller than in PA6 or PA66, but it remains significant enough that design calculations for snap fits, creep, and electrical insulation must specify the moisture condition rather than treating PA12 as moisture-insensitive.

Because the Dry designation is not equivalent to permanent dimensional stability, incoming material should be protected from ambient humidity above 60 % RH. Dry property data cannot be transferred directly to parts that will operate in water-saturated or high-humidity service; the relevant conditioned properties should be measured at the expected service moisture uptake.

Representative dry-as-molded mechanical and thermal values for the unreinforced Grilamid L 22A family are shown below. The W 40X black weathering configuration may shift values within supplier tolerance bands, and lot-specific certificates should govern purchase specifications.

Drying and melt-processing conditions for this grade follow standard PA12 practice, but the dry state imposes measurable constraints on high-output molding. Desiccant drying at 80 °C for 4–8 h is normally adequate when starting from sealed packaging; the recommended inlet dew point is at or below -30 °C. Material exposed to ambient air above 60 % RH may require extended drying to return below 0.10 wt% residual moisture. Barrel set temperatures are typically profiled from 220 °C at the feed throat to 250 °C at the nozzle, and the melt should not be held above 280 °C for extended cycles. At melt temperatures above 300 °C or residence times beyond 10 min, the weathering additive package can undergo discoloration and the polyamide backbone can show chain scission, producing black specks, gate blush, and a measurable drop in melt viscosity. Screw configurations with L/D from 20:1 to 25:1 and compression ratio near 2.5:1 are suitable; the nonreturn valve and nozzle should be free of dead spots because PA12 melt can adhere to hot surfaces and form carbonized material. Mold temperature should be maintained between 40 °C and 80 °C. The lower range supports short cycles for thin-wall clips, while the upper range improves crystallization, dimensional stability, and weld-line toughness in thicker sections.

On production machinery, two failure modes are commonly observed when the dry specification is ignored. Insufficient drying produces silver streaks and porosity at the gate; excessive melt temperature produces brown streaks or dark specks from stabilizer degradation. Weld lines in black weather-stabilized PA12 are typically the limiting design feature rather than the bulk tensile property, because the black pigment particle size and distribution affect weld-line strength. Prototype parts should therefore be molded with the intended gate location, not machined from test bars, when validating snap-fit retention force.

When outdoor weathering and sub-zero impact toughness dictate grade selection

The W 40X suffix distinguishes this product from natural L 22A and from heat-stabilized but non-weathering PA12 grades. In EMS-Grivory practice, a W-associated formulation is selected for exterior service because the black pigmentation and stabilizer system reduce surface degradation caused by ultraviolet radiation. Laboratory weathering under ISO 4892-2 with filtered xenon-arc exposure and water spray is commonly used to screen color change and gloss retention, but OEM specifications usually define acceptance limits for elongation retention, impact retention, or appearance. For parts that must survive winter impact at -30 °C, the PA12 backbone provides higher ductility than many unreinforced PA6 or PA66 grades because the glass transition temperature is below 50 °C and the polymer remains tough in the dry state. The black weathering package may produce a modest reduction in Charpy notched impact energy compared with natural L 22A; published data for the exact L 22A W 40X dry configuration is limited, so end-use qualification should be performed on production-molded parts with the specified gate and color.

A comparison with plasticized PA12 or impact-modified PA12 is relevant. Plasticized grades may show higher low-temperature impact but can lose plasticizer by migration, causing embrittlement and dimensional change. Grilamid L 22A W 40X is not considered a plasticized grade, although the base PA12 is inherently ductile. The weathering grade should be selected when the part is black, externally exposed, and service temperature does not exceed the thermal limits of unreinforced PA12.

Dimensional tolerance, creep and electrical insulation boundaries

Unreinforced PA12 has lower modulus and higher elongation than glass-filled PA12 or semi-aromatic polyamides. A dry flexural modulus near 1200–1300 MPa under ISO 178 means structural deflection under load is greater than with reinforced alternatives. Snap-fit designs should conservatively use the dry yield strain of 4–5 % for repeated assembly, and creep calculations must account for moisture, temperature, and stress level. The coefficient of linear thermal expansion for unreinforced PA12 is higher than for steel or aluminum, so inserts and overmolded metal components may create high thermal-stress concentration. If a design requires HDT/A above 90 °C, unreinforced PA12 is generally unsuitable because the dry HDT/A is only 50–55 °C; reinforced PA66 or polyphthalamide should be used instead.

Electrical insulation is normally high for unreinforced PA12, with volume resistivity values above 10¹² Ω·m under IEC 62631-3-1. The black pigment in the W 40X formulation may reduce surface resistivity or alter comparative tracking index compared with natural PA12. If the component is an electrical connector or sensor housing, the specific compound and color must be qualified under the end-use electrical safety standard rather than assumed from natural-grade table values.

The material-selection difference between EMS-Grivory Grilamid L 22A W 40X Nylon 12, Dry and the more common PA6 or PA66 families is based on moisture uptake, low-temperature ductility, and thermal resistance. PA6 has a density near 1.13–1.14 g/cm³ and water saturation near 9–10 wt%; PA66 has a density near 1.13–1.15 g/cm³ and water saturation near 7–9 wt%. These higher amide concentrations provide higher dry HDT and stiffness, but they produce greater dimensional change with humidity and larger property shifts between dry and conditioned states. PA12 at 1.01 g/cm³ and 1.4–1.6 wt% saturation absorbs less water, which is beneficial in humid or wet service. However, PA12 is not the correct replacement for PA66 in hot load-bearing applications because its dry HDT/A is much lower. Within the Grilamid L family, L 22A W 40X differs from unfilled natural PA12 by its weathering and black-related stabilization package, not by large changes in modulus or melting point. It differs from glass-reinforced Grilamid grades by lower modulus, higher elongation, and lower density, making it preferable for snap-fit rather than structural tensile applications.

Regulatory compliance must be verified against grade-specific documentation

For automotive, electrical, and industrial applications, material compliance cannot be inferred from base polymer identity. The relevant declarations for RoHS 2011/65/EU, REACH, and any OEM-specific requirements such as volatile organic compound or fogging limits should be confirmed with the supplier for the exact L 22A W 40X color lot. The presence of weathering additives and carbon black may affect food-contact or potable-water suitability, so FDA 21 CFR or EU 10/2011 status should not be assumed. UL 94 ratings, if required, must be read from the UL Yellow Card for the specific grade and thickness; unreinforced PA12 is often rated HB, but the black variant may have a different listing. Chemical resistance of PA12 is generally strong in aliphatic hydrocarbons, diesel fuel, hydraulic fluids, greases, and salt solutions, but the material is not recommended for continuous service in strong mineral acids, strong polar solvents, phenol, or steam above 100 °C. In hot water or acid environments, hydrolysis attacks the amide bond and reduces molecular weight, leading to cracking under external stress.

Production-scale validation of EMS-Grivory Grilamid L 22A W 40X Nylon 12, Dry should include drying verification with a moisture analyzer or dew-point meter, at least one low-temperature impact set from molded parts, and a weathering benchmark if the intended service is exterior. Drying is not a one-time setting; batch size, hopper airflow, and plant relative humidity create batch-to-batch variation. The most common field failure is not base polymer failure but improper drying at the press or excessive melt residence time. For components with snap-fit arms, geometry and gate location control orientation and weld-line placement more than the dry tensile data suggest. When the operating environment includes sub-zero impact, UV exposure, and incidental contact with oils or fuel, the L 22A W 40X grade is a technically plausible candidate only if the part design accepts the thermal limit of unreinforced PA12 and the moisture-sensitivity rules of dry-material handling are applied.