EMS-Grivory Grilamid® LBKN-50H FWA BLACK 9225 is a heat-stabilised, glass-bead-filled polyamide 12 compound identified under ISO 1043-1 as PA12-GB50. The 50H suffix denotes a 50% by mass spherical glass-bead loading. The B character distinguishes glass-bead reinforcement from short-glass-fibre or mineral-reinforced grades; K indicates heat stabilisation. FWA identifies the food- and water-contact approval lineage, while BLACK 9225 defines the carbon black-tinted colour package. The compound is intended for injection moulding and extrusion where resistance to hydrocarbon-based chemicals, low moisture uptake, dimensional stability, and isotropic shrinkage are simultaneous requirements.

Specification compliance begins with the characterisation methods in the table below. Values for this grade are generated on dry-as-moulded specimens at 23 °C and 50% relative humidity after conditioning to ISO 291. The presence of 50% glass beads increases melt viscosity and improves creep resistance compared with unfilled PA12. The compound is not a conductive grade; its electrical behaviour remains typical of insulating polyamide compounds. Exact physical-property values must be confirmed against the current EMS-Grivory technical datasheet because conditioning state, specimen thickness, and colour batch can shift results.

The FWA approval does not transfer automatically to fabricated articles. Under FDA 21 CFR 177.1500, the base polyamide 12 resin may be cleared for food contact, but the finished part must satisfy end-use limitations for food type, contact temperature, and contact duration. For EU Regulation (EU) No 10/2011, overall migration testing is performed on the final article. Processing aids, colour package constituents, and trace decomposition products formed during moulding contribute to the migration budget. The black 9225 colour package must be verified against the batch-specific compliance certificate if the part is intended for repeated-use potable-water contact.

What Processing Parameters Protect a 50% Glass-Bead Dispersion State?

Glass-bead-filled polyamide 12 does not require fibre-opening shear, but it demands sufficient heat and pressure to wet the bead surface and break down occasional bead agglomerates. Dispersion failures appear as localised viscosity fluctuation, splay along flow fronts, and variation in ash content between first and last shots. Production-scale processing has shown that glass beads can settle in long hot-runner manifolds if residence time exceeds 8–10 minutes, particularly when melt temperature remains above 270 °C. Excessive barrel temperature accelerates oxidative degradation of the heat-stabiliser package and generates volatile decomposition products and discoloration. The practical melt-temperature window is therefore narrow: melt temperature at the nozzle is typically maintained between 240 °C and 270 °C.

Drying is the first critical control. The compound must be pre-dried to a moisture content below 0.10% by mass. A desiccant dryer operating at 80 °C with a dew point below -30 °C and drying time of 4–8 hours is appropriate for most black PA12 glass-bead grades. At relative humidity above 60%, open-air feedstock handling from sealed bags should not exceed 15 minutes; otherwise surface moisture adsorption increases and can generate splay and weak weld lines. Drying hopper capacity should match hourly consumption so that dried granules do not remain in the hopper for more than 6 hours.

Injection moulding machines with general-purpose screws having L/D ratios between 20:1 and 24:1 are commonly used. A low-compression screw is preferred because glass beads increase bulk density and reduce feeding variability. Recommended compression ratio is usually in the range 2.0:1 to 2.5:1. The non-return valve should be a sliding-ring design with hardened components; glass-bead abrasion can increase clearance and reduce shot-weight consistency. Screw and barrel wear from glass-bead-filled compounds is lower than from glass-fibre-filled compounds, but bimetallic barrels and nitrided screws are still specified for production volumes above 1,000,000 cycles.

Mould temperature controls crystallisation and sink development. For dimensional stability, mould temperatures of 60 °C to 90 °C are applied. Lower mould temperatures may be used where cycle time dominates and post-mould shrinkage can be accepted. Higher mould temperatures reduce internal stress and improve surface finish on black parts, but they extend cycle time. Venting with land thickness of 0.01–0.03 mm is used to avoid gas burns from moisture or additive volatiles. Gate dimensions should be at least 50–70% of wall thickness for circular gates. Weld-line tensile strength in glass-bead-filled PA12 is typically lower than in unfilled PA12 because the spherical beads do not bridge across the melt front.

Fluid-management and potable-water components represent the dominant application volume for this grade. Typical parts include water meter housings, pump impellers, filter heads, valve bodies, sprinkler internals, and beverage dispenser manifolds. The component requirements are mechanical stiffness, creep resistance under hydrostatic pressure, low moisture-induced swelling, and resistance to chlorinated potable water. The glass-bead filler reduces the coefficient of linear thermal expansion relative to unfilled PA12, as measured by ISO 11359-2. This reduces clearance changes in metal-to-plastic assemblies between 23 °C and 80 °C. The filler also produces more isotropic mould shrinkage than short-glass-fibre PA12. ISO 294-4 measurements show that longitudinal and transverse shrinkage differences are smaller, which reduces out-of-round distortion in cylindrical bodies.

Creep under internal water pressure is evaluated on finished parts according to ISO 9080 or national product standards such as NSF/ANSI 14 and KIWA Water Mark procedures. The PA12 base offers lower saturated water absorption than PA66 or PA6; ISO 62 values for glass-bead-filled PA12 depend on filler content but are below those of PA66-GB grades. Saturated water absorption influences dimensional change and electrical properties, but it should not be used as a proxy for hydrolytic stability in hot chlorinated water. For continuous hot-water service above 65 °C, the approval documentation should be checked because glass-bead-filled PA12 may not retain the same hydrostatic design stress as PP-R or PSU in pressure vessels.

Compared with PA12-GF30, this grade trades tensile modulus and tensile strength for lower warpage, reduced machine wear, smoother surfaces, and lower anisotropy. Compared with PA66-GB50, it offers lower water absorption and better resistance to zinc chloride stress cracking, but lower heat deflection temperature. Compared with unfilled PA12, the glass-bead filler reduces creep strain, increases stiffness, and raises heat deflection temperature while preserving much of the base polymer’s chemical resistance.

Dimensional Stability Under Humid and Thermal Cycling

The substitution of 50% by mass spherical glass beads for polymer reduces equilibrium water uptake per unit mass and restricts volumetric expansion. This is measurable as a reduction in the coefficient of linear thermal expansion, ISO 11359-2, and as lower hygroscopic growth after immersion in water to ISO 62. The effect is not linearly additive because the polyamide interphase around the bead surface can immobilise water and expand. Glass beads also increase heat deflection temperature relative to unfilled PA12, as measured under ISO 75-1/-2. At 1.8 MPa, the increase is moderate because the polymer matrix still dominates flexural deformation; at 0.45 MPa, the improvement is more apparent.

Creep under load is assessed by ISO 899-1. Glass beads reduce creep strain by restricting chain slip and by transferring stress to rigid particles. However, creep resistance remains dependent on moisture content. At 50% relative humidity, conditioned specimens show lower creep modulus than dry-as-moulded specimens because water plasticises the amorphous regions. Design calculations for pressurised components during a 50-year service life should use conditioned creep curves rather than dry tensile modulus.

Shrinkage anisotropy is one of the main reasons to select PA12-GB50 over PA12-GF30. In glass-fibre-filled materials, longitudinal shrinkage is far lower than transverse shrinkage because fibre orientation controls contraction. In glass-bead-filled materials, the filler is nearly spherical and the shrinkage difference is reduced. This allows mould designers to use lower draft angles and more uniform wall sections. The ratio of transverse to longitudinal shrinkage can be examined with ISO 294-4 plaques; datasheet values for this grade should be used to correct cavity dimensions. Post-mould shrinkage at elevated service temperature, such as 80 °C in hot water, must also be included in the mould compensation plan. Rapid thermal cycling can produce different shrinkage than isothermal moulding because crystallinity and internal stress vary.

When Chemical Exposure and Food-Water Compliance Define the Approval Boundary

The FWA formulation is selected for repeated food and potable-water contact, but no plastic material is universally resistant. Polyamide 12 is attacked by concentrated strong acids, oxidising agents, phenols, and hot glycol mixtures. In potable-water use, the main stressors are chlorine dioxide, free chlorine, pH excursions, and stagnation. The resin supplier’s chemical resistance database should be consulted for the specific disinfectant concentration and temperature. For free chlorine residuals above 1 mg/L at temperatures above 60 °C, published data for this specific configuration are limited, and the final part should be tested under end-use conditions. National approval protocols such as NSF/ANSI 61 or BS 6920 provide additional extraction and product-safety criteria.

The FWA designation does not cover all food simulants. Under Regulation (EU) No 10/2011, migration testing may include 10% ethanol, 3% acetic acid, 20% ethanol, 50% ethanol, and olive oil or iso-octane depending on the food type. Fatty food contact at elevated temperature is more demanding than aqueous food contact and may require additional migration data. The black 9225 formulation includes carbon black; the specific migration limit for heavy metals and primary aromatic amines must be confirmed on the finished article.

Chemical incompatibility during processing and service should also be managed. Introducing amine-based processing aids or certain copper-free stabiliser systems may interact with the FWA package and should be avoided unless validated. In secondary operations such as ultrasonic welding, weld strength can be reduced by the glass-bead filler if joint design does not provide enough molten polymer volume; a shear joint is preferred over an energy director joint for filled materials. Hot-plate welding of PA12-GB50 produces good weld strength if the melt layer is kept at a thickness of 0.2 mm to 0.5 mm and welding pressure is controlled to avoid squeezing out the polymer-rich melt film.

After machining or adhesive bonding, stress cracking may occur if the parts contact alcohols or ketones. Isopropyl alcohol at room temperature is often used for cleaning, but prolonged immersion can cause environmental stress cracking in stressed injection moulded components. For assemblies that undergo repeated steam sterilisation, published data for this specific configuration are limited and autoclave trials are required. PA12 generally is not the preferred candidate for superheated steam sterilisation above 121 °C because the polymer approaches melting.