EMS-Grivory Grilamid TR 90 UV is specified in injection-molded spectacle frame manufacturing where dry-as-molded transparency, low density, and dimensional stability at the hinge and nose bridge are required. The grade is an amorphous transparent polyamide identified as PAMACM12, produced from bis(3-methyl-4-aminocyclohexyl)methane and dodecanedioic acid; the dry-state density is 1.00 g/cm³ according to ISO 1183-1:2019 and the glass transition is approximately 155 °C. Before molding, the resin is dried in a desiccant dryer at 80 °C for 4–8 h until residual moisture is below 0.10 %; after initial drying, closed-loop hopper drying at 60 °C is maintained and open-air residence is kept below 2 h. For colored frames, a polyamide-carrier color masterbatch is metered at 2–4 wt %. Regranulated sprues and runners are limited to 10–15 wt % because higher recycled content reduces notched Charpy impact measured per ISO 179-1:2020 and increases optical haze measured per ISO 14782. Molding is conducted on a servo-electric or hydraulic machine with a screw L/D of 20–25; nozzle melt temperature is maintained at 250–270 °C and mold temperature at 60–80 °C. Injection speed is set to the fastest profile that avoids jetting, and sequential valve gating is used in multi-cavity tools to move weld lines away from hinge and nose-bridge stress concentrations. Terminal components include prescription frames, sports sunglass frames, and safety spectacle frames; frame-level dimensional stability and endurance are assessed under ISO 12870:2016, while complete certified protectors are tested under EN 166 or ANSI Z87.1 depending on target market.

In frame color development, the masterbatch carrier must be compatible with PAMACM12 because PA6 or PA66 carriers introduce refractive-index discontinuities and streak defects along rim-to-temple transitions. Gravimetric dosing is held within ±0.1 wt % for optical colors. Outdoor color retention is verified by ISO 4892-2 at a buyer-specified irradiance and exposure energy, not by a universal UV life claim.

When Aqueous Alcohol and Alkaline Detergent Streams Contact Transparent PAMACM12

In aqueous alcohol and alkaline detergent service, transparent PAMACM12 components are molded from Grilamid TR 90 UV because the unfilled material resists environmental stress cracking in media that rapidly damage polycarbonate and acrylic. Qualification is performed by immersion under applied flexural strain according to ISO 175:2010; the test fluid is the unfiltered production stream rather than a laboratory solvent substitute because minor impurities control crack initiation. Industrial equipment compliance is assessed under RoHS 2011/65/EU and REACH SVHC obligations. Potable water or food-contact status is not claimed automatically; specific lots must be checked against EU 10/2011 or FDA 21 CFR 177.1500 because the UV stabilizer package can affect migration limits. The formulation is unfilled: glass fiber, mineral filler, and impact modifiers are excluded because they create refractive-index discontinuities and potential crack-initiation sites in aggressive fluids. Wetted surfaces are molded from 100 % virgin material. Regrind from adequately dried sprues is restricted to 20 wt % only in non-wetted retaining rings and housings. Amine-based additive masterbatches and copper-halide heat-stabilizer masterbatches are avoided; amine carriers can shift the apparent molecular weight distribution and reduce stress-crack resistance in alcohol service, while copper-halide systems induce haze in transparent sections.

Melt temperature is held at 255–275 °C and mold temperature at 80–100 °C; the higher mold temperature reduces residual stress but increases cycle time. After ejection, parts with metal inserts or continuous internal pressure are annealed at 90 °C for 1–2 h to lower molded-in stress before exposure to aqueous alcohol; unannealed parts can develop microcracks at weld lines and insert boundaries. Hot-runner manifolds are avoided for wet-chemical parts with flow length above 100 mm because residence-time distribution increases molecular weight degradation. Published data for the specific chemical compatibility of Grilamid TR 90 UV with ketone-rich or concentrated aromatic hydrocarbon streams is limited; those fluids require long-term creep-stress immersion rather than short-duration coupon testing. Terminal components include transparent filter bowls, pump sight-glasses, level-indicator tubes, dosing-pump housings, and solvent sight windows for process equipment.

In automotive interior light guides and machine-control panel windows, Grilamid TR 90 UV is selected where repeated contact with cleaning agents and thin-wall multi-cavity filling must be combined without secondary hard-coating. Dry-as-molded light transmittance at 2 mm is typically above 90 % when measured according to ISO 13468-1; this value is an incoming resin control rather than a guaranteed part property because wall thickness and injection speed shift final part haze. Compliance for control-panel windows is evaluated under IEC 60695-2-11 glow-wire testing when the panel belongs to unattended equipment; ignition resistance is documented on the UL Yellow Card according to UL 94 HB at the specified wall thickness. For clear parts, no mineral or white masterbatch is added. Smoke-tint or signal-color components are produced with a polyamide-carrier masterbatch at 0.5–1.5 wt %; higher doses create viscosity heterogeneity and streaking in the gate region. Drying is performed at 80 °C for 4 h to below 0.10 % moisture.

Melt temperature is controlled within ±5 °C of the 260–275 °C center set point because wider swings alter flow-front position in a multi-cavity tool and change weld-line visibility. Mold temperature is maintained at 70–90 °C. For a 1.0 mm nominal wall, screw-forward speed is set at 150–300 mm/s on a 40 mm plasticating unit; holding pressure is switched by cavity-pressure measurement to avoid gate sink and flow-end overpacking. Gate geometry uses a fan gate or flash gate at the non-visible edge; edge gates create jetting in thin transparent flow channels. The runner is balanced to obtain equal filling pressure across cavities, and valve gates are used where cosmetics require a low gate vestige. Terminal products include automotive interior light guides, control-panel windows, LED indicator lens covers, and transparent switch trim.

What Limits Weathering Retention in Unpainted Outdoor Sensor Windows?

Unpainted outdoor sensor windows and camera housings are molded from Grilamid TR 90 UV when the assembly requires a transparent, low-mass polyamide window with integrated snap-fit and sealing geometries that cannot be formed in glass. The embedded UV stabilizer system is designed to reduce photochemical chain scission in unfilled PAMACM12, but the stabilizer is consumed over time; color shift and haze development are therefore evaluated by accelerated exposure under ASTM G154 or ISO 4892-2 using a fixed irradiance and black-standard temperature. There is no universal outdoor life value for this material because spectral power distribution and sample temperature control the degradation route. Independent long-term outdoor weathering data for this specific formulation are not published; accelerated weathering certificates supplied by the resin manufacturer remain the primary qualification basis, so acceptance limits for yellowing index and transmission loss must be fixed by the end user before validation.

Sealing faces and overmolded inserts are produced from 100 % virgin material to avoid contamination-induced leakage. Metal inserts are heated to 150–180 °C before overmolding; lower insert temperatures create interface skins that reduce bond strength, higher temperatures initiate local polymer degradation. Molding uses a melt temperature of 255–270 °C and a mold temperature of 80–100 °C; after machining, parts are annealed at 90 °C for 1 h to stabilize dimensions. The terminal enclosures are rated to IP65 or IP67 under IEC 60529 after final assembly, not at the window material level. Terminal products include outdoor sensor windows, electrical cabinet sight-glasses, and agricultural camera windows.

For transparent reservoirs and flow indicators in commercial cleaning machines, Grilamid TR 90 UV is used when the service fluid contains non-food detergent solutions, low-molecular-weight alcohols, or aliphatic hydrocarbon rinses that stress-crack polycarbonate and acrylic. Gravimetric dosing controls the formulation; colored reservoirs use a polyamide-carrier masterbatch at 1–3 wt %, while fully transparent sight-tubes use 0 % masterbatch and limit regrind to 10 wt % to keep haze variation within sight-glass quality limits. Drying follows the same resin-specific threshold of 80 °C for 4 h to residual moisture below 0.10 %. Melt temperature is held at 250–270 °C; mold temperature is held at 60–80 °C. Injection speed is medium to high, and packing pressure is limited by cavity-pressure peak to prevent internal stress at the reservoir bottom weld line. Compliance is assessed under IEC 60335-1:2020 for electrical appliance safety where the reservoir is an unheated, non-pressurized component; material declarations follow RoHS 2011/65/EU and REACH SVHC. Terminal products include washing-machine sight glasses, detergent dosing reservoirs, rinse-agent level tubes, and non-potable water reservoirs for commercial humidifiers.