Coextruded capstock for cellular PVC window profiles and architectural siding places SABIC GELOY™ ASA CR7020 in direct contact with a high-CTE substrate where cap-to-substrate shrinkage mismatch generates interfacial shear across every thermal cycle. Cap layer thickness is typically set at 0.15–0.25 mm, not as a percentage of total wall thickness, on a conical twin-screw coextruder fitted with a slot die and calibrator table. CR7020 is pre-dried to below 0.05% moisture using a desiccant dryer at 80–85 °C for 3–4 h prior to line start-up. Melt temperature for the cap layer is held between 215 °C and 230 °C while the rigid PVC substrate runs at 185–195 °C to limit degradation at the feedblock. Drawdown at the calibrator is maintained below 2% to avoid cap-layer thinning at corners, where ultraviolet protective thickness drops below 0.10 mm; published data for CR7020 in this specific coextrusion configuration is limited, but commercial capstock line practice associates corner thinning with early color shift under exposure. Compliance for finished window lineals and siding panels is verified against ASTM D3679-22, AAMA 303-18, and ISO 4892-2:2013 xenon arc exposure for 3000 h. Architectural specifications commonly require ΔE ≤ 3.0 against retained dark-shade control specimens. Impact retention is measured by falling-weight impact per ASTM D5420-21, with no brittle fracture after 1500 h accelerated weathering. Terminal components include dark brown and black window lineals, siding panels, and fascia boards.

What Limits Regrind Ratio When CR7020 Replaces Painted ABS in Exterior Mirror Housings?

Replacement of painted ABS with molded-in-color CR7020 in exterior mirror housings removes the paint line but tightens control over regrind fraction and heat history. Recommended virgin-to-regrind ratio is 70:30 by weight; sprues and runners generated from hot-runner tools are dried to below 0.05% moisture and reintroduced at a consistent 30% fraction to avoid lot-to-lot Izod scatter. Melt temperature is set at 240–260 °C, mold surface temperature at 50–70 °C, and injection fill time between 1.0 s and 2.5 s on a 180–250 t hydraulic clamp platform. Published ISO data place notched Izod impact strength for CR7020 in the 12–18 kJ/m² range at 23 °C under ISO 180/A:2023; weld lines in mirror housing screw bosses can retain less than 50% of bulk value if melt temperature at the weld falls below 240 °C. Compliance for exterior automotive plastics is evaluated by SAE J2527 xenon arc exposure to 2500 kJ/m², with surface gloss retention assessed per ISO 2813:2014. Terminal components are sail-mounted mirror housings, door handle escutcheons, and B-pillar base covers.

Underbonnet thermal oscillation, not ultraviolet exposure, drives design of CR7020 cowl vent grilles for agricultural utility vehicles and compact tractors. Continuous exposure to 80 °C air above the rear engine cowl reduces tensile elongation over service life; the component is designed around an ISO tensile yield range of 38–42 MPa when measured by ISO 527-2:2012 and a coefficient of linear thermal expansion near 8.5–9.5 × 10⁻⁵ K⁻¹ under ISO 11359-2:2021. Molding is performed with a melt temperature of 230–250 °C and an oil-heated mold at 60–80 °C to minimize the skin-core differential that produces bowing across a 900 mm grille span. Gate placement moves the weld line to a non-flanged edge; prototypes are aged for 500 h at 85 °C in a forced-air circulating oven to confirm absence of visible exudation or gloss change. Low-temperature impact retention is evaluated by ISO 179-1/1eA:2023 at -30 °C after 1000 h of SAE J2527 exposure. Terminal finished goods include cowl vent grilles, windshield surround panels, and cab roof edge trims.

When Spa Shell Thermoforming Demands 4.0 mm Sheet Without Pre-Form Moisture Bloom

Monolithic spa shells and whirlpool tubs are fabricated from CR7020 sheet that has been extruded, dried, and thermoformed with particular attention to residual moisture below 0.05%. Sheet extrusion is performed on a 90 mm single-screw vented extruder fitted with a 1200 mm coat-hanger die; die temperature is profiled at 230 °C center and 225 °C edges, while the polishing stack runs at 60–70 °C. Regrind reuse is capped at 20% by weight because higher regrind fractions lower melt extensional viscosity and produce sag variation of more than ±2 mm in a 4.0 mm sheet during radiative heating. Heating for thermoforming uses a two-sided quartz oven with sheet surface temperatures of 150–170 °C; the sheet core reaches 120 °C before 60 kPa vacuum forming. Chemical resistance of the formed shell is assessed by immersion in 5 ppm free chlorine buffered water at 40 °C for 500 h per ISO 175:2010. Stress whitening at the plug-assist corner is rejected if visible after 24 h relaxation under 0.5% tensile strain. Terminal components are single-piece spa shells, swim-spa lower bowls, and bath surround panels.

In street-level telecom cabinet housings, CR7020 is used as the UV-stable structural shell rather than the flame-retardant internal partition. Because the grade is not a flame-retardant formulation, enclosure designers use CR7020 only for the outer shell and separate UL 94 V-0 rated internal partitions if the application demands compliance with IEC 61969-3:2020. Molding uses a melt temperature of 240–255 °C and pulsed cooling with a mold temperature of 65 °C; gate sizing is designed for a shear rate below 50,000 s⁻¹ to avoid gate blush on flat housing faces. Sun-exposed panels are evaluated by ISO 4892-2:2013 for 2000 h; color change is measured by ISO 11664-4:2020 against the original molded plaque with ΔE ≤ 2.5. Brass insert pull-out resistance is tested in accordance with ISO 19252:2021 after 500 thermal cycles from -40 °C to +80 °C; boss wall thickness is maintained at 2.0 mm minimum to avoid radial cracking. Regulatory conformity for assembled enclosures follows 2011/65/EU RoHS Recast and IEC 61969-1. Terminal assembled goods are outdoor telecom cabinets, pole-mounted controllers, and compact distributed-energy enclosures.

Sheet Extrusion Die-Pressure Control in Dark Architectural Cladding

Sheet extrusion for dark-colored exterior cladding rarely fails from UV chalking; it fails at the edge trim line when melt pressure variation exceeds 10%. CR7020 cladding sheet and sign faces are extruded through a 90 mm 38 L/D barrier screw with melt pump and a flex-lip die; melt pressure variation is held below ±0.5 bar across the die width. Pre-drying at 80–85 °C to below 0.05% moisture prevents surface splay and edge voids. Regrind from skeleton and trim scrap is capped at 20% by weight because higher coarse regrind content raises die pressure by 8–12% on 1.8 mm sheet. Extruded sheet is evaluated for tensile elongation at break by ISO 527-3:2018 at 23 °C; a minimum 20% elongation is retained after 1500 h ISO 4892-2 exposure for signage manufacturers. Terminal products include formed roadside sign faces, dark architectural cladding panels, and kiosk enclosure skins.